**Table 1.**

*Effect of cover crop and N fertilization rate on yield and N uptake by cotton lint, sorghum grain, and their biomass (stems + leaves) from 2000 to 2002 in central Georgia, USA [16].*

#### *Nitrogen Fertilization I: Impact on Crop, Soil, and Environment DOI: http://dx.doi.org/10.5772/intechopen.86028*

by using legume cover crops, such as red clover (*Trifolium incarnatum* L.) and hairy vetch (*Vicia villosa* Roth), regardless of tillage practices [18]. The high rate of N fertilization can produce excessive vegetative growth that delays maturity and

*Effects of cropping sequence and N fertilization rate on malt barley grain yield, N uptake, and N-use efficiency in eastern Montana, USA. CTB-F denotes conventional-till malt barley-fallow; NTB-F, no-till malt barleyfallow; NTB-P, no-till malt barley-pea; and NTCB, no-till continuous malt barley. Vertical bar with LSD*

Nitrogen-use efficiency, defined as crop yield or N uptake per unit applied N fertilizer, is a useful measurement of the efficiency of N fertilization to crop yields [5]. Enhancing N-use efficiency can maximize crop yield and N uptake with limited use of fertilizer N while reducing N rate and sustaining the environment [3]. Nitrogen-use efficiency, however, can decrease with increased N fertilization rate due to the inability of crops to utilize N efficiently [5]. Sainju et al. [10] found that N-use efficiency by malt barley decreased curvilinearly with increased N fertilization rate (**Figure 2**). Varvel and Peterson [5] reported that N removed by corn and sorghum grain was 50% of the applied N at low N rates and at least 20–30% at high

harvest and reduces cotton lint yield and N uptake [19].

*(0.05) is the least significant difference between treatments at P = 0.05 [10].*

N rates.

**72**

**Figure 2.**

*Nitrogen Fixation*

#### **Figure 3.**

*Linear and quadratic responses of shoot biomass in perennial grasses with N fertilization rates from 2011 to 2013 averaged across grass species in eastern Montana, USA [20].*

Nitrogen fertilization can also increase aboveground biomass yield of perennial grasses used for feedstock or bioenergy production. Sainju et al. [20] observed that yields of intermediate wheatgrass (*Thinopyrum intermedium* [Host] Barkworth and Dewey), switchgrass (*Panicum virgatum* L.), and smooth bromegrass (*Bromus inermis* L.) increased linearly or curvilinearly with increased N fertilization rate in 2011 and 2013 (**Figure 3**) when the annual precipitation was near or above the average. Biomass yield, however, did not respond to N fertilization in 2012 when the annual precipitation was below the average. Several researchers [21, 22] reported that maximum switchgrass shoot biomass yield reached at 120– 140 kg N ha<sup>1</sup> in Iowa and Nebraska, USA, which had 2.5 and 2.2 times, respectively, more annual precipitation than in eastern Montana, USA. Power [23] also observed increased shoot biomass yield with increased N rate for smooth bromegrass in North Dakota, USA.

#### **3. Soil acidification**

Application of NH4-based N fertilizers can increase soil acidity due to the release of H ions during hydrolysis [24]. Increased soil acidity following the application of N fertilizers leads to the development of infertile soils that do not respond well to crop yields with further application of N fertilizers [2, 25], thereby resulting in inefficient use of fertilizers [26]. Sainju et al. [27] reported that, after 30 years of tillage and cropping sequence, continuous application of N fertilizers reduced soil pH at the 0–7.5 cm depth from 6.30 at the initiation of the experiment to 5.73 in spring till spring wheat-fallow (STW-F) and to 5.02 in fall and spring till continuous spring wheat (FSTCW) under rainfed condition in eastern Montana, USA (**Table 2**). A similar decline in soil pH at 7.5–15.0 cm was observed from 6.75 at the initiation of the experiment to 6.15 in spring till continuous spring wheat (STCW). Buffer pH, the buffering capacity of the soil to resist changes in pH and is used to measure lime requirement, also similarly decreased with continuous N fertilization in all treatments. Both pH and buffer pH, however, did not change below 15 cm with N fertilization. Because spring wheat was grown once in 2 years in spring wheat-fallow rotation where N fertilizer was applied only to spring wheat, soil pH

was less declined in this treatment than continuous spring wheat where N fertilizer was applied every year. From the same experiment, Aase et al. [28] reported an average decline of pH at 0–7.5 cm from 6.3 to 5.7 after 10 years due to continuous N

*Effect of tillage and crop rotation combination on soil pH and buffer pH at the 0–120 cm depth after 30 years*

**Soil depth 0–7.5 cm 7.5–15 cm 15–30 cm 30–60 cm 60–90 cm 90–120 cm**

E<sup>c</sup> 6.50abD 7.60C 8.35B 8.58A 8.75A

STCW 5.05bE 6.15bD 7.58C 8.25B 8.63A 8.70A FSTCW 5.02bE 6.33bD 7.80C 8.30B 8.68AB 8.73A FSTW-B/P 5.46aE 6.44bD 7.60C 8.15B 8.51A 8.59A STW-F 5.73aE 7.03aD 7.65C 8.25B 8.50AB 8.66A

NT vs. T 0.29 0.26 0.09 0.08 0.08 0.04 CW vs. W-F 0.68\*\*\* 0.88\*\* 0.08 0.01 0.13 0.04 CW vs. W-B/P 0.43\* 0.11 0.20 0.15 0.16 0.14

NTCW 6.45bE 7.10abD 7.43C 7.60B 7.70AB 7.73A STCW 6.38bE 7.00bD 7.43C 7.58B 7.68A 7.70A FSTCW 6.43bE 7.05bD 7.45C 7.60B 7.70AB 7.73A FSTW-B/P 6.66aD 7.13abC 7.44B 7.58B 7.69AB 7.70A STW-F 6.80aE 7.24aD 7.44C 7.59B 7.66AB 7.72A

NT vs. T 0.05 0.08 0.01 0.01 0.01 0.01 CW vs. W-F 0.43\*\*\* 0.24\*\* 0.01 0.01 0.01 0.01 CW vs. W-B/P 0.24\* 0.08 0.01 0.03 0.01 0.03

*FSTCW, fall and spring till continuous spring wheat; FSTW-B/P, fall and spring till spring wheat-barley (1994– 1999) followed by spring wheat-pea (2000–2013); NTCW, no-till continuous spring wheat; STCW, spring till continuous spring wheat; and STW-F, spring till spring wheat-fallow. CW represents continuous wheat; NT, no-till;*

*Numbers followed by the same lowercase letter within a column among treatments in a set are not significantly*

*Numbers followed by the same uppercase letter within a row among soil depths in a set are no significantly different at*

Ghimire et al. [29] found that soil pH at 0–10 cm after 70 years of N fertilization was 5.70 with 0 kg N ha<sup>1</sup> and 5.0 with 135–180 kg N ha<sup>1</sup> under winter wheatfallow in eastern Oregon, USA (**Figure 4**). Reduction in pH with N fertilization decreased with depth, with no significant effect below 30 cm. A study in China, where intensive farming and high rate of N fertilizer was applied for 20 years, showed that soil pH was dropped by 0.30–0.80 units from the original level [30]. In eastern Oregon, USA, application of total N fertilizer at 2.25 Mg N ha<sup>1</sup> over the 43 year period lowered soil pH by 0.60 units [31]. Liebig et al. [26] reported that, in

fertilization.

**75**

*different at P <sup>≤</sup> 0.05. <sup>c</sup>*

**Tillage and cropping**

NTCW 5.33abb

*DOI: http://dx.doi.org/10.5772/intechopen.86028*

*Nitrogen Fertilization I: Impact on Crop, Soil, and Environment*

*Significant at P = 0.05, 0.01, and 0.001, respectively. \*\*Significant at P = 0.05, 0.01, and 0.001, respectively. \*\*\*Significant at P = 0.05, 0.01, and 0.001, respectively. <sup>a</sup>*

*of experiment initiation in eastern Montana, USA [27].*

*T, till; W-B/P, spring wheat-barley/pea; and W-F, spring wheat-fallow.*

**sequence<sup>a</sup>**

Contrast

Buffer pH

Contrast

*\**

*b*

*P ≤ 0.05.*

**Table 2.**

pH


#### *Nitrogen Fertilization I: Impact on Crop, Soil, and Environment DOI: http://dx.doi.org/10.5772/intechopen.86028*

*\* Significant at P = 0.05, 0.01, and 0.001, respectively.*

*\*\*Significant at P = 0.05, 0.01, and 0.001, respectively.*

*\*\*\*Significant at P = 0.05, 0.01, and 0.001, respectively. <sup>a</sup>*

*FSTCW, fall and spring till continuous spring wheat; FSTW-B/P, fall and spring till spring wheat-barley (1994– 1999) followed by spring wheat-pea (2000–2013); NTCW, no-till continuous spring wheat; STCW, spring till continuous spring wheat; and STW-F, spring till spring wheat-fallow. CW represents continuous wheat; NT, no-till; T, till; W-B/P, spring wheat-barley/pea; and W-F, spring wheat-fallow.*

*b Numbers followed by the same lowercase letter within a column among treatments in a set are not significantly different at P <sup>≤</sup> 0.05. <sup>c</sup>*

*Numbers followed by the same uppercase letter within a row among soil depths in a set are no significantly different at P ≤ 0.05.*

#### **Table 2.**

Nitrogen fertilization can also increase aboveground biomass yield of perennial grasses used for feedstock or bioenergy production. Sainju et al. [20] observed that yields of intermediate wheatgrass (*Thinopyrum intermedium* [Host] Barkworth and Dewey), switchgrass (*Panicum virgatum* L.), and smooth bromegrass (*Bromus inermis* L.) increased linearly or curvilinearly with increased N fertilization rate in 2011 and 2013 (**Figure 3**) when the annual precipitation was near or above the average. Biomass yield, however, did not respond to N fertilization in 2012 when the annual precipitation was below the average. Several researchers [21, 22] reported that maximum switchgrass shoot biomass yield reached at 120– 140 kg N ha<sup>1</sup> in Iowa and Nebraska, USA, which had 2.5 and 2.2 times, respectively, more annual precipitation than in eastern Montana, USA. Power [23] also observed increased shoot biomass yield with increased N rate for smooth brome-

*Linear and quadratic responses of shoot biomass in perennial grasses with N fertilization rates from 2011 to*

*2013 averaged across grass species in eastern Montana, USA [20].*

Application of NH4-based N fertilizers can increase soil acidity due to the release of H ions during hydrolysis [24]. Increased soil acidity following the application of N fertilizers leads to the development of infertile soils that do not respond well to crop yields with further application of N fertilizers [2, 25], thereby resulting in inefficient use of fertilizers [26]. Sainju et al. [27] reported that, after 30 years of tillage and cropping sequence, continuous application of N fertilizers reduced soil pH at the 0–7.5 cm depth from 6.30 at the initiation of the experiment to 5.73 in spring till spring wheat-fallow (STW-F) and to 5.02 in fall and spring till continuous

spring wheat (FSTCW) under rainfed condition in eastern Montana, USA

(**Table 2**). A similar decline in soil pH at 7.5–15.0 cm was observed from 6.75 at the initiation of the experiment to 6.15 in spring till continuous spring wheat (STCW). Buffer pH, the buffering capacity of the soil to resist changes in pH and is used to measure lime requirement, also similarly decreased with continuous N fertilization in all treatments. Both pH and buffer pH, however, did not change below 15 cm with N fertilization. Because spring wheat was grown once in 2 years in spring wheat-fallow rotation where N fertilizer was applied only to spring wheat, soil pH

grass in North Dakota, USA.

**3. Soil acidification**

**74**

**Figure 3.**

*Nitrogen Fixation*

*Effect of tillage and crop rotation combination on soil pH and buffer pH at the 0–120 cm depth after 30 years of experiment initiation in eastern Montana, USA [27].*

was less declined in this treatment than continuous spring wheat where N fertilizer was applied every year. From the same experiment, Aase et al. [28] reported an average decline of pH at 0–7.5 cm from 6.3 to 5.7 after 10 years due to continuous N fertilization.

Ghimire et al. [29] found that soil pH at 0–10 cm after 70 years of N fertilization was 5.70 with 0 kg N ha<sup>1</sup> and 5.0 with 135–180 kg N ha<sup>1</sup> under winter wheatfallow in eastern Oregon, USA (**Figure 4**). Reduction in pH with N fertilization decreased with depth, with no significant effect below 30 cm. A study in China, where intensive farming and high rate of N fertilizer was applied for 20 years, showed that soil pH was dropped by 0.30–0.80 units from the original level [30]. In eastern Oregon, USA, application of total N fertilizer at 2.25 Mg N ha<sup>1</sup> over the 43 year period lowered soil pH by 0.60 units [31]. Liebig et al. [26] reported that, in

surface residue that partly immobilizes N than CT where fertilizers are incorporated into the soil due to tillage [33]. Because of enhanced soil water conservation, crop yields are higher in NT than CT, especially in dryland cropping systems [34]. As a result, crops remove more basic cations, resulting in increased acidity with NT compared with CT [34]. In contrast, Ghimire et al. [29] reported that soil pH

Source of N fertilizer can also have a varying effect on soil acidity. Chen et al.

(NH4)2SO4 > NH4Cl > NH4NO3 > anhydrous NH3 > urea. Similarly, Schroder et al. [25] reported that anhydrous NH3 produce more acidity than urea. Others [35], however, observed no significant differences in acidity among (NH4)2SO4,

Soil organic matter refers to soil organic C and N and is a crucial component of soil health and quality [36, 37]. Nitrogen fertilization can increase soil organic C and N by increasing crop biomass yield, and the amount of residue returned to the soil [38]. Russell et al. [37], however, reported no difference in soil organic C with N fertilization rate. Sainju et al. [39] reported that 3 years of N fertilization to cotton and sorghum produced various results on soil organic C at the 0–30 cm depth in strip-tilled and chisel-tilled soils in central Georgia, USA (**Table 3**). Soil organic C at 0–10 and 10–30 cm varied with N fertilization rates in strip-tilled soil, but increased in chisel-tilled soil due to differences in tillage intensity. In strip tillage, only crop rows are tilled, leaving the area between rows undisturbed, and N fertilizer is applied in crop rows. In contrast, the land is tilled using discs in chisel tillage after N fertilizer is broadcast. Differences in N fertilization methods between tillage practices probably affected soil organic C due to N fertilization rates.

Sainju [9] observed different trends of soil organic C at the 0–120 cm depth with 6 years of N fertilization rates in various cropping systems in eastern Montana, USA (**Figure 5**). Soil organic C at 0–5 and 5–10 cm peaked at 40 kg N ha<sup>1</sup> and then declined with further increase in N rates in no-till malt barley-pea (NTB-P) and continuous no-till barley (NTCB). In no-till malt barley-fallow (NTB-F) and

**)**

**0–10 cm 10–30 cm 30–60 cm 60–90 cm 90–120 cm**

**N rate (kg N ha1) Soil organic C (Mg C ha<sup>1</sup>**

0 10.1a<sup>a</sup> 16.0a 10.9 7.2 5.5 60–65 9.3b 14.4b 10.2 4.5 5.3 120–130 10.3a 14.7ab 9.8 7.3 5.8

0 8.9b 12.5b 10.1 7.4 5.9 60–65 9.6a 13.4b 10.1 7.3 5.3 120–130 9.3ab 14.8a 10.6 7.9 6.1

*Numbers followed by the same letter within a column in a set are not significantly different at P ≤ 0.05.*

*soils under cotton and sorghum in central Georgia, USA [39].*

*Effect of 3 years of N fertilization rate on soil organic C at the 0–120-cm depth in strip-tilled and chisel-tilled*

decreased with increased N rate, as tillage intensity increased.

*Nitrogen Fertilization I: Impact on Crop, Soil, and Environment*

*DOI: http://dx.doi.org/10.5772/intechopen.86028*

found that soil acidity from N fertilizer sources was in the order

NH4NO3, anhydrous NH3, urea, and urea-NH4NO3.

**4. Soil organic matter**

Strip-tilled soil

Chisel-tilled soil

*a*

**77**

**Table 3.**

**Figure 4.**

*Soil pH at the 0–60 cm depth from N fertilization rates to winter wheat in the winter wheat-fallow rotation after 70 years in eastern Oregon, USA. Bars with different letters at the top are significantly different at P ≤ 0.05 [29].*

North Dakota, USA, soil pH at 0–7.6 cm was lower under continuous corn than corn rotated with legume and other nonlegume crops because of the increased amount of N fertilizer applied. They recommended that soil samples be collected to a depth of 15 cm for measuring changes in soil pH due to N fertilization.

No-till (NT) system can increase soil acidity more than the conventional till (CT) system [32]. This is due to differences in the amount and placement of N fertilizers in the soil and removal of basic cations through grain and biomass removal between the two tillage systems [32]. Nitrogen fertilizers are usually placed at the soil surface, and N rates are usually higher in NT due to the accumulation of

*Nitrogen Fertilization I: Impact on Crop, Soil, and Environment DOI: http://dx.doi.org/10.5772/intechopen.86028*

surface residue that partly immobilizes N than CT where fertilizers are incorporated into the soil due to tillage [33]. Because of enhanced soil water conservation, crop yields are higher in NT than CT, especially in dryland cropping systems [34]. As a result, crops remove more basic cations, resulting in increased acidity with NT compared with CT [34]. In contrast, Ghimire et al. [29] reported that soil pH decreased with increased N rate, as tillage intensity increased.

Source of N fertilizer can also have a varying effect on soil acidity. Chen et al. found that soil acidity from N fertilizer sources was in the order (NH4)2SO4 > NH4Cl > NH4NO3 > anhydrous NH3 > urea. Similarly, Schroder et al. [25] reported that anhydrous NH3 produce more acidity than urea. Others [35], however, observed no significant differences in acidity among (NH4)2SO4, NH4NO3, anhydrous NH3, urea, and urea-NH4NO3.

#### **4. Soil organic matter**

Soil organic matter refers to soil organic C and N and is a crucial component of soil health and quality [36, 37]. Nitrogen fertilization can increase soil organic C and N by increasing crop biomass yield, and the amount of residue returned to the soil [38]. Russell et al. [37], however, reported no difference in soil organic C with N fertilization rate. Sainju et al. [39] reported that 3 years of N fertilization to cotton and sorghum produced various results on soil organic C at the 0–30 cm depth in strip-tilled and chisel-tilled soils in central Georgia, USA (**Table 3**). Soil organic C at 0–10 and 10–30 cm varied with N fertilization rates in strip-tilled soil, but increased in chisel-tilled soil due to differences in tillage intensity. In strip tillage, only crop rows are tilled, leaving the area between rows undisturbed, and N fertilizer is applied in crop rows. In contrast, the land is tilled using discs in chisel tillage after N fertilizer is broadcast. Differences in N fertilization methods between tillage practices probably affected soil organic C due to N fertilization rates.

Sainju [9] observed different trends of soil organic C at the 0–120 cm depth with 6 years of N fertilization rates in various cropping systems in eastern Montana, USA (**Figure 5**). Soil organic C at 0–5 and 5–10 cm peaked at 40 kg N ha<sup>1</sup> and then declined with further increase in N rates in no-till malt barley-pea (NTB-P) and continuous no-till barley (NTCB). In no-till malt barley-fallow (NTB-F) and


#### **Table 3.**

*Effect of 3 years of N fertilization rate on soil organic C at the 0–120-cm depth in strip-tilled and chisel-tilled soils under cotton and sorghum in central Georgia, USA [39].*

North Dakota, USA, soil pH at 0–7.6 cm was lower under continuous corn than corn rotated with legume and other nonlegume crops because of the increased amount of N fertilizer applied. They recommended that soil samples be collected to

*Soil pH at the 0–60 cm depth from N fertilization rates to winter wheat in the winter wheat-fallow rotation after 70 years in eastern Oregon, USA. Bars with different letters at the top are significantly different at*

No-till (NT) system can increase soil acidity more than the conventional till (CT) system [32]. This is due to differences in the amount and placement of N fertilizers in the soil and removal of basic cations through grain and biomass removal between the two tillage systems [32]. Nitrogen fertilizers are usually placed at the soil surface, and N rates are usually higher in NT due to the accumulation of

a depth of 15 cm for measuring changes in soil pH due to N fertilization.

**Figure 4.**

**76**

*P ≤ 0.05 [29].*

*Nitrogen Fixation*

#### **Figure 5.**

*Soil organic C at the 0–120 cm depth as affected by 6 years of N fertilization rates to malt barley in various cropping systems in eastern Montana, USA. CTB-F denotes conventional-till malt barley-fallow; NTB-F, notill malt barley-fallow; NTB-P, no-till malt barley-pea; and NTCB, no-till continuous malt barley. Vertical bars denote least significant difference between tillage and cropping sequence treatments within a N rate at P = 0.05 [9].*

conventional till malt barley-fallow (CTB-F), the trend of soil organic C with N rates varied at various depths. Soil organic C at these depths was greater with NTB-P and NTCB than other treatments at most N rates due to greater amount of crop residue returned to the soil. Soil organic C at 5–10, 30–60, and 60–90 cm were greater with 40 kg N ha<sup>1</sup> than other N rates. Sainju [9] also found that C sequestration rate at 0–10 cm was 83 kg C ha<sup>1</sup> year<sup>1</sup> with 40 kg N ha<sup>1</sup> that was close to 94 kg C ha<sup>1</sup> year<sup>1</sup> at 0–15 cm with 45 kg N ha<sup>1</sup> for dryland cropping systems in Colorado [36].

Under perennial grasses, several researchers [40, 41] did not find a significant effect of N fertilization on soil organic C at 0–30 cm after 2–5 years in Alabama and Colorado, USA. Only after 4–12 years, N fertilization increased soil organic C at 0– 90 cm by 0.5–2.4 Mg C ha<sup>1</sup> year<sup>1</sup> compared with no N fertilization under switchgrass in USA and Canada [42, 43]. Rice et al. [43] reported that N fertilization to cool-season grasses increased C sequestration rate at 0–30 cm by 1.6 Mg C ha<sup>1</sup> year<sup>1</sup> compared with no N fertilization after 5 years in Kansas, USA. In Alberta, Canada, Bremer et al. [42] observed that N fertilization to perennial grasses increased C sequestration rate at 0–5 cm by 0.5 Mg C ha<sup>1</sup> year<sup>1</sup> compared with no N fertilization after 6–12 years. In South Dakota, USA, Li et al. [44] noted C sequestration rate of 2.4 Mg C ha<sup>1</sup> year<sup>1</sup> at 0–90 cm under switchgrass after 4 years. Sainju et al. [45] found increasing trend of soil total C at 30–60 cm with increased N rate under intermediate wheatgrass and smooth bromegrass and a declining trend with switchgrass after 5 years in eastern Montana (**Figure 6**). At 60–90 cm, the trend reversed with grasses. They suggested that longer than 5 years is needed to observe the effect of N fertilization on soil total C under perennial grasses.

chisel-tilled soil in central Georgia, USA (**Figure 7**). Ghimire et al. [29] observed that soil total N at 10–20 cm increased with increased N rates after 70 years of N fertilization to winter wheat, but the trend varied with different tillage practices

*Soil total N at 0–120 cm in the chisel-tilled soil as affected by 6 years of N fertilization rates to cotton and sorghum in central Georgia, USA. Bars with the same letter at the top are not significantly different among N*

*Soil total C at 30–60 and 60–90 cm depths as affected by 5 years of N fertilization rates to perennial grasses in eastern Montana, USA. Perennial grasses are IW, intermediate wheatgrass; SB, smooth bromegrass, and SW, switchgrass. LSD (0.05) is least significant difference between grasses within a N rate at P = 0.05 [45].*

*Nitrogen Fertilization I: Impact on Crop, Soil, and Environment*

*DOI: http://dx.doi.org/10.5772/intechopen.86028*

Increased N substrate availability due to N fertilization along with tillage may have increased microbial activity and N mineralization and therefore reduced soil total

, soil total N was lower with disc plow than other tillage practices.

, soil

at higher N rates in eastern Oregon, USA (**Figure 8**). At 0–45 kg N ha<sup>1</sup>

180 kg N ha<sup>1</sup>

*rates at a depth at P ≤ 0.05 [46].*

**Figure 7.**

**Figure 6.**

N over time.

**79**

total N was greater with subsurface sweep than a moldboard plow. At 90–

Nitrogen fertilization has less impact on soil total N than soil organic C. Sainju and Singh [46] reported that soil total N at 0–15 cm under cotton and sorghum was greater with 60–65 than 0 kg N ha<sup>1</sup> , but not at lower depths in the

**Figure 6.**

conventional till malt barley-fallow (CTB-F), the trend of soil organic C with N rates varied at various depths. Soil organic C at these depths was greater with NTB-P and NTCB than other treatments at most N rates due to greater amount of crop residue returned to the soil. Soil organic C at 5–10, 30–60, and 60–90 cm were greater with 40 kg N ha<sup>1</sup> than other N rates. Sainju [9] also found that C sequestration rate at 0–10 cm was 83 kg C ha<sup>1</sup> year<sup>1</sup> with 40 kg N ha<sup>1</sup> that was close to 94 kg C ha<sup>1</sup> year<sup>1</sup> at 0–15 cm with 45 kg N ha<sup>1</sup> for dryland cropping systems in

*Soil organic C at the 0–120 cm depth as affected by 6 years of N fertilization rates to malt barley in various cropping systems in eastern Montana, USA. CTB-F denotes conventional-till malt barley-fallow; NTB-F, notill malt barley-fallow; NTB-P, no-till malt barley-pea; and NTCB, no-till continuous malt barley. Vertical bars denote least significant difference between tillage and cropping sequence treatments within a N rate at*

Under perennial grasses, several researchers [40, 41] did not find a significant effect of N fertilization on soil organic C at 0–30 cm after 2–5 years in Alabama and Colorado, USA. Only after 4–12 years, N fertilization increased soil organic C at 0– 90 cm by 0.5–2.4 Mg C ha<sup>1</sup> year<sup>1</sup> compared with no N fertilization under switchgrass in USA and Canada [42, 43]. Rice et al. [43] reported that N fertilization to cool-season grasses increased C sequestration rate at 0–30 cm by 1.6 Mg C ha<sup>1</sup> year<sup>1</sup> compared with no N fertilization after 5 years in Kansas, USA. In Alberta, Canada, Bremer et al. [42] observed that N fertilization to perennial grasses increased C sequestration rate at 0–5 cm by 0.5 Mg C ha<sup>1</sup> year<sup>1</sup> compared with no

N fertilization after 6–12 years. In South Dakota, USA, Li et al. [44] noted C sequestration rate of 2.4 Mg C ha<sup>1</sup> year<sup>1</sup> at 0–90 cm under switchgrass after 4 years. Sainju et al. [45] found increasing trend of soil total C at 30–60 cm with increased N rate under intermediate wheatgrass and smooth bromegrass and a declining trend with switchgrass after 5 years in eastern Montana (**Figure 6**). At 60–90 cm, the trend reversed with grasses. They suggested that longer than 5 years is needed to observe the effect of N fertilization on soil total C under perennial

Nitrogen fertilization has less impact on soil total N than soil organic C. Sainju and Singh [46] reported that soil total N at 0–15 cm under cotton and sorghum

, but not at lower depths in the

Colorado [36].

**Figure 5.**

*Nitrogen Fixation*

*P = 0.05 [9].*

grasses.

**78**

was greater with 60–65 than 0 kg N ha<sup>1</sup>

*Soil total C at 30–60 and 60–90 cm depths as affected by 5 years of N fertilization rates to perennial grasses in eastern Montana, USA. Perennial grasses are IW, intermediate wheatgrass; SB, smooth bromegrass, and SW, switchgrass. LSD (0.05) is least significant difference between grasses within a N rate at P = 0.05 [45].*

**Figure 7.**

*Soil total N at 0–120 cm in the chisel-tilled soil as affected by 6 years of N fertilization rates to cotton and sorghum in central Georgia, USA. Bars with the same letter at the top are not significantly different among N rates at a depth at P ≤ 0.05 [46].*

chisel-tilled soil in central Georgia, USA (**Figure 7**). Ghimire et al. [29] observed that soil total N at 10–20 cm increased with increased N rates after 70 years of N fertilization to winter wheat, but the trend varied with different tillage practices at higher N rates in eastern Oregon, USA (**Figure 8**). At 0–45 kg N ha<sup>1</sup> , soil total N was greater with subsurface sweep than a moldboard plow. At 90– 180 kg N ha<sup>1</sup> , soil total N was lower with disc plow than other tillage practices. Increased N substrate availability due to N fertilization along with tillage may have increased microbial activity and N mineralization and therefore reduced soil total N over time.

#### **Figure 8.**

*Soil total N as affected by 72 years of N fertilization rates to spring wheat and tillage in eastern Oregon, USA. Tillage practices are DP, disk plow; MP, moldboard plow, and SW, subsurface sweep. Bars with different lowercase letters at the top are significantly different among tillage practices within a N rate at P ≤ 0.05. Bars with different uppercase letters at the top are significantly different among N rates within a tillage practice at P ≤ 0.05 [29].*

#### **5. Soil residual nitrogen and nitrogen leaching**

Soil residual N refers to inorganic N (NH4-N + NO3-N) accumulated in the soil profile after crop harvest. This occurs because crops cannot take up all applied N fertilizer from the soil [5, 47]. Accumulation of soil NO3-N increases with depth and is directly related to N fertilization rate [47, 48]. Deep accumulation of NO3-N in the soil profile increases the potential for N leaching to shallow water tables [49]. Nitrogen fertilization rates that exceed crop requirement can increase NO3-N accumulation in the soil profile and N leaching [50].


#### **Table 4.**

*Effect of cover crop and N fertilization rate on soil residual inorganic N (NH4-N + NO3-N) content at the 0–30 cm depth in central Georgia, USA [16].*

**N** 

**81**

kg N ha1

0 40 80 120 *†Numbers followed by the same letters within a column are not significantly*

**Table 5.** *Effect of N fertilization*

 *rate on soil residual NH4-N content at the 0–120 cm depth from 2006 to 2011 in eastern Montana,*

**fertilization**

 **rate**

 **NH4-N content at the soil depth**

**0–5 cm**

kg N ha1

2.4b†

2.3b

2.5b

2.9a

 2.6a

 10.8a

 16.2a

 *different at P ≤ 0.05.*

 19.6a

 25.7a

 5.5a

 *USA [55].*

 16.1a

 32.0a

 50.8a

 73.6a

 2.5a

 10.3a

 15.5a

 19.7a

 25.1a

 5.0ab

 15.4a

 30.8a

 49.1a

 72.2a

 2.3a

 10.6a

 15.4a

 19.7a

 25.0a

 4.7b

 15.2a

 30.6a

 49.7a

 72.7a

2.5a

 10.4a

 15.8a

 19.4a

 23.8a

 4.9b

 15.3a

 31.2a

 50.2a

 72.0a

 **5–10 cm**

 **10–30 cm**

 **30–60 cm**

 **60–90 cm**

 **90–120 cm**

 **0–10 cm**

 **0–30 cm**

 **0–60 cm**

 **0–90 cm**

 **0–120 cm**

*Nitrogen Fertilization I: Impact on Crop, Soil, and Environment*

*DOI: http://dx.doi.org/10.5772/intechopen.86028*



 *USA [55].*

**Table**

*Effect of N fertilization*

 *rate on soil residual NH4-N content at the 0–120 cm depth from 2006 to 2011 in eastern Montana,*

*Nitrogen Fertilization I: Impact on Crop, Soil, and Environment DOI: http://dx.doi.org/10.5772/intechopen.86028*

**5. Soil residual nitrogen and nitrogen leaching**

**Figure 8.**

*Nitrogen Fixation*

*P ≤ 0.05 [29].*

**Soil inorganic N**

N fertilization rate (kg N ha<sup>1</sup>

*0–30 cm depth in central Georgia, USA [16].*

(kg N ha<sup>1</sup> )

Cover crop

*a*

**80**

**Table 4.**

mulation in the soil profile and N leaching [50].

)

Soil residual N refers to inorganic N (NH4-N + NO3-N) accumulated in the soil profile after crop harvest. This occurs because crops cannot take up all applied N fertilizer from the soil [5, 47]. Accumulation of soil NO3-N increases with depth and is directly related to N fertilization rate [47, 48]. Deep accumulation of NO3-N in the soil profile increases the potential for N leaching to shallow water tables [49]. Nitrogen fertilization rates that exceed crop requirement can increase NO3-N accu-

**Treatment 0–10 cm 10–30 cm 0–30 cm**

Winter weeds 19.6b<sup>a</sup> 32.9b 52.5c Rye 19.1b 34.1b 53.2c Hairy vetch 23.6a 38.4a 62.0a Hairy vetch/rye 21.6a 34.8b 56.4b

0 19.6b 33.5b 53.1b 60–65 20.8b 35.3ab 56.1ab 120–130 22.5a 36.4a 59.9a

*Numbers followed by the same letter within a column in a set are not significantly different at P ≤ 0.05.*

*Effect of cover crop and N fertilization rate on soil residual inorganic N (NH4-N + NO3-N) content at the*

*Soil total N as affected by 72 years of N fertilization rates to spring wheat and tillage in eastern Oregon, USA. Tillage practices are DP, disk plow; MP, moldboard plow, and SW, subsurface sweep. Bars with different lowercase letters at the top are significantly different among tillage practices within a N rate at P ≤ 0.05. Bars with different uppercase letters at the top are significantly different among N rates within a tillage practice at*


**Table 6.**

*Effect N fertilization rate on soil residual NO3-N content at the 0–120 cm depth from 2006 to 2011 in eastern Montana, USA [55].* One of the ways to reduce N fertilization rates to crops while maintaining yield

<sup>3</sup> content to a depth of 60 cm after crop harvest in the

**– 6**).

3-N contamination of groundwater [56]. This

3-N accumulation in the soil profile [57] due to N

2], nitrous oxide [N

<sup>2</sup> equivalents from farm inputs, farm operations, soil

<sup>4</sup> emissions [61, 62]. The net GWP for a crop

<sup>4</sup> uptake) as well as CO

3-N content due to greater N

–20% of global

<sup>2</sup> emissions associ-

2

. Net GWP is also

2O], and methane

3-N

4-N and NO

goals is to account for N mineralized from soil organic matter during the crop growing season and soil residual N at crop planting [6]. Since the measurement of N mineralization requires a long time, N fertilization rates to dryland crops are

previous year or at planting of the current year from recommended N rates [51]. Producers are increasingly interested in reducing the amount of N fertilizer applied to crops because of the higher cost of N fertilization and the associated environ-

tional till system due to greater accumulation of surface crop residue that can enhance N immobilization [52]. On the other hand, N rates can be reduced in crop rotations containing legumes compared to monoculture nonlegume cropping systems [53]. Nonlegume monocropping can have higher soil residual NO3-N content than legume-based crop rotations due to increased N fertilization rate [5, 27].

immobilization, less summer fallow, and a greater amount of N removed by crops

fertilization rates that exceed crop requirements, accompanied by poor soil and crop management practices [56]. Nitrate-N accumulation and movement in the soil profile depend on soil properties, climatic conditions, and management practices [58]. For example, N leaching is greater in sandy than clayey soils due to the presence of a large number of macropores and leaching is higher in the humid than arid and semiarid regions due to differences in annual precipitation [56, 58]. Nitrate-N leaching occurs mostly in the fall, winter, and spring seasons in the northern hemisphere when evapotranspiration is low, crops are absent to uptake soil N, and precipitation exceeds the water holding capacity of the soil [59].

**6. Greenhouse gas emissions and global warming potential**

Management practices on croplands can contribute about 10

4]) [60]. Quantitative estimate of the impact of the GHGs to global radiative forcing is done by calculating net global warming potential (GWP) which accounts

> <sup>2</sup> eq. ha <sup>1</sup> year 1

expressed as net greenhouse gas intensity (GHGI) or yield-scaled GWP, which is calculated by dividing net GWP by crop yield [61]. These values can be affected both by net GHG emissions and crop yields. Sources of GHGs in agroecosystems

ated with farm machinery used for tillage, planting, harvesting, and manufacture, transportation, and applications of chemical inputs, such as fertilizers, herbicides, and pesticides, while soil C sequestration rate can be either a sink or source of CO

greenhouse gases (GHGs: carbon dioxide [CO

production system is expressed as kg CO

2O and CH

<sup>4</sup> emissions (or CH

for all sources and sinks of CO

2O and CH

C sequestration, and N

[CH

include N

**83**

It is well known that excessive N fertilizer application can increase N leaching in the groundwater, which is a major environmental concern [50]. Nitrate-N concentration >10 mg L<sup>1</sup> in the drinking water poses a serious threat to human and animal health [56]. Nitrate-N is soluble in water and moves down the soil profile with percolating water [47, 57]. Increased application of N fertilizer to crops during the

Increased cropping intensity can reduce soil profile NO

*Nitrogen Fertilization I: Impact on Crop, Soil, and Environment*

*DOI: http://dx.doi.org/10.5772/intechopen.86028*

contents increased with N rates and depths (**Tables 4**

last several decades has increased NO

occurs because of excessive NO

[54]. Sainju et al. [16] and Sainju [9] found that both soil NH

Nitrogen fertilization rates to crops can be higher in the no-till than the conven-

adjusted by deducting soil NO

mental degradation.

#### *Nitrogen Fertilization I: Impact on Crop, Soil, and Environment DOI: http://dx.doi.org/10.5772/intechopen.86028*

One of the ways to reduce N fertilization rates to crops while maintaining yield goals is to account for N mineralized from soil organic matter during the crop growing season and soil residual N at crop planting [6]. Since the measurement of N mineralization requires a long time, N fertilization rates to dryland crops are adjusted by deducting soil NO3 content to a depth of 60 cm after crop harvest in the previous year or at planting of the current year from recommended N rates [51]. Producers are increasingly interested in reducing the amount of N fertilizer applied to crops because of the higher cost of N fertilization and the associated environmental degradation.

Nitrogen fertilization rates to crops can be higher in the no-till than the conventional till system due to greater accumulation of surface crop residue that can enhance N immobilization [52]. On the other hand, N rates can be reduced in crop rotations containing legumes compared to monoculture nonlegume cropping systems [53]. Nonlegume monocropping can have higher soil residual NO3-N content than legume-based crop rotations due to increased N fertilization rate [5, 27]. Increased cropping intensity can reduce soil profile NO3-N content due to greater N immobilization, less summer fallow, and a greater amount of N removed by crops [54]. Sainju et al. [16] and Sainju [9] found that both soil NH4-N and NO3-N contents increased with N rates and depths (**Tables 4–6**).

It is well known that excessive N fertilizer application can increase N leaching in the groundwater, which is a major environmental concern [50]. Nitrate-N concentration >10 mg L<sup>1</sup> in the drinking water poses a serious threat to human and animal health [56]. Nitrate-N is soluble in water and moves down the soil profile with percolating water [47, 57]. Increased application of N fertilizer to crops during the last several decades has increased NO3-N contamination of groundwater [56]. This occurs because of excessive NO3-N accumulation in the soil profile [57] due to N fertilization rates that exceed crop requirements, accompanied by poor soil and crop management practices [56]. Nitrate-N accumulation and movement in the soil profile depend on soil properties, climatic conditions, and management practices [58]. For example, N leaching is greater in sandy than clayey soils due to the presence of a large number of macropores and leaching is higher in the humid than arid and semiarid regions due to differences in annual precipitation [56, 58]. Nitrate-N leaching occurs mostly in the fall, winter, and spring seasons in the northern hemisphere when evapotranspiration is low, crops are absent to uptake soil N, and precipitation exceeds the water holding capacity of the soil [59].

#### **6. Greenhouse gas emissions and global warming potential**

Management practices on croplands can contribute about 10–20% of global greenhouse gases (GHGs: carbon dioxide [CO2], nitrous oxide [N2O], and methane [CH4]) [60]. Quantitative estimate of the impact of the GHGs to global radiative forcing is done by calculating net global warming potential (GWP) which accounts for all sources and sinks of CO2 equivalents from farm inputs, farm operations, soil C sequestration, and N2O and CH4 emissions [61, 62]. The net GWP for a crop production system is expressed as kg CO2 eq. ha<sup>1</sup> year<sup>1</sup> . Net GWP is also expressed as net greenhouse gas intensity (GHGI) or yield-scaled GWP, which is calculated by dividing net GWP by crop yield [61]. These values can be affected both by net GHG emissions and crop yields. Sources of GHGs in agroecosystems include N2O and CH4 emissions (or CH4 uptake) as well as CO2 emissions associated with farm machinery used for tillage, planting, harvesting, and manufacture, transportation, and applications of chemical inputs, such as fertilizers, herbicides, and pesticides, while soil C sequestration rate can be either a sink or source of CO2

**N** 

**82**

**kg N ha1**

0 40 80 120 *†Numbers followed by the same letters within a column are not significantly*

**Table 6.** *Effect N fertilization*

 *rate on soil residual NO3-N content at the 0–120 cm depth from 2006 to 2011 in eastern Montana,*

**kg N ha1**

6.7c† 8.1c

10.1b

12.2a

 6.2a

 20.0a

 23.4a

 *different at P ≤ 0.05.*

 21.7a

 24.7a

 18.3a

 *USA [55].*

 38.2a

 61.7a

 83.3a

 107.0a

 5.1b

 16.7b

 19.8b

 17.7b

 21.0ab

 15.2b

 31.9b

 51.8b

 69.4b

 89.6b

 4.3bc

 14.6c

 17.5bc

 17.1b

 21.4ab

 12.5c

 27.1c

 44.6c

 61.6c

 82.3b

3.7c

 13.3c

 15.5c

 13.7c

 16.7b

 10.2c

 23.6d

 39.0d

 52.7d

 68.7c

**fertilization**

 **rate**

 **NO3-N content at the soil depth**

**0–5 cm**

 **5–10 cm**

 **10–30 cm**

 **30–60 cm**

 **60–90 cm**

 **90–120 cm**

 **0–10 cm**

 **0–30 cm**

 **0–60 cm**

 **0–90 cm**

 **0–120 cm**

*Nitrogen Fixation*

[62, 63]. In the calculations of net GWP and GHGI, emissions of N2O and CH4 are converted into their CO2 equivalents of global warming potentials which are 310 and 28, respectively, for a time horizon of 100 years [60]. The balance between soil C sequestration rate, N2O and CH4 emissions (or CH4 uptake), and crop yield typically controls net GWP and GHGI [61, 62].

Nitrogen fertilization typically stimulates N2O emissions when the amount of applied N exceeds crop N demand [51, 61]. Nitrogen fertilization, however, can have a variable effect on emissions of other GHGs, such as CO2 and CH4 [64, 65]. Sainju et al. [65] found that the application of 80 kg N ha<sup>1</sup> to dryland malt barley increased CO2 emissions, but not N2O and CH4 emissions (**Table 7**). Because N2O emissions has a large effect on net GWP and GHGI, practices that can reduce N fertilization rates without influencing crop yields can substantially reduce net GHG emissions [61, 62]. Other factors that can influence N2O emissions are the type, placement, time, and method of application of N fertilizers. Applying N fertilizer in the spring compared with autumn and using split application compared with one single application at planting can reduce N2O emissions in some cases [66]. Applying N fertilizer at various depths can have a variable effect on N2O emissions [67]. Anhydrous ammonia can increase N2O emissions compared with urea [67, 68]. Similarly, chemical additives to reduce nitrification from N fertilizers, such as polymer-coated urea and nitrification inhibitors, can substantially reduce N2O emissions compared with ordinary urea and non-nitrification inhibiting fertilizers [69]. Some N fertilizers, such as urea, emit both CO2 and N2O. Nitrogen fertilizers also indirectly emit N2O through NH3 volatilization and NO3-N leaching [68].

Increased N fertilization rate can enhance net GWP and GHGI due to increased N2O and CO2 emissions associated with the manufacture, transport, and application of N fertilizers, regardless of cropping systems and calculation methods [61, 70]. In a meta-analysis of 12 experiments, Sainju [71], after accounting for all sources and sinks of CO2 emissions, reported that net GWP decreased from 0 to ≤45 kg N ha<sup>1</sup> and net GHGI from 0 to ≤145 kg N ha<sup>1</sup> and then increased with increased N fertilization rate (**Figure 9**). Using partial accounting, net GWP decreased from 0 to 88 kg N ha<sup>1</sup> and net GHGI from 0 to ≤213 kg N ha<sup>1</sup> and then increased with increased N rate. These N rates probably corresponded to crop N demand when crops used most of the soil available N. The cropping systems that left little residual N in the soil reduced N2O emissions, and therefore net GWP and GHGI, whereas net GWP and GHGI increased linearly with increase in N application rates that exceeded crop N demand, suggesting that excessive N fertilizer applications can induce global warming. Similar results have been reported by Li et al. [44]. Therefore, N fertilizers should be applied at optimum rates to reduce net GWP and GHGI while sustaining crop yields. The optimum N rates, however, depended on net GWP measured either per unit area or per unit crop yield.


Sainju [71] observed that the relationships between net GWP, net GHGI, and N

residue returned to the soil, soil C sequestration rate, and grain yields were greater

, the amount of plant

rate were further improved when the duration of the experiment and soil and climatic conditions were taken into account in the multiple linear regressions. Duration of experiment and annual precipitation had positive effects, but air temperature and soil texture had negative effects on net GWP when all sources and sinks of CO2 emissions were accounted for. With partial accounting, only air temperature had a positive effect on net GWP, but other factors had negative effects. For net GHGI, the factors having negative effects were air temperature using the complete accounting of CO2 emissions and annual precipitation and soil texture using the partial accounting. Sainju et al. [70] reported that net GWP and GHGI calculated from soil respiration and soil C sequestration methods were lower with 80 than 0 kg N ha<sup>1</sup> (**Table 8**). They noted that, although CO2 equivalents from N

*The relationship between N fertilization rate and net global warming potential (GWP) and greenhouse gas intensity (GHGI). Full accounting data denote calculations of GWP and GHGI by accounting all sources and sinks of CO2 (N2O and CH4 emissions, farm inputs, operations, and soil C sequestration). Partial accounting data denotes partial accounting of sources and sinks (N2O and CH4 emissions and/or soil C sequestration). All*

fertilization and soil respiration were higher with 80 kg N ha<sup>1</sup>

*data denotes inclusions of full and partial accounting data [71].*

*Nitrogen Fertilization I: Impact on Crop, Soil, and Environment*

*DOI: http://dx.doi.org/10.5772/intechopen.86028*

**Figure 9.**

**85**

*† Numbers followed by different letters within a column are significantly different at P ≤ 0.05 by the least square means test.*

#### **Table 7.**

*Effect of N fertilization on total soil surface greenhouse gas fluxes (from March to November) averaged across years from 2008 to 2011 under rainfed malt barley in eastern Montana, USA [65].*

*Nitrogen Fertilization I: Impact on Crop, Soil, and Environment DOI: http://dx.doi.org/10.5772/intechopen.86028*

**Figure 9.**

[62, 63]. In the calculations of net GWP and GHGI, emissions of N2O and CH4 are converted into their CO2 equivalents of global warming potentials which are 310 and 28, respectively, for a time horizon of 100 years [60]. The balance between soil C sequestration rate, N2O and CH4 emissions (or CH4 uptake), and crop yield

Nitrogen fertilization typically stimulates N2O emissions when the amount of applied N exceeds crop N demand [51, 61]. Nitrogen fertilization, however, can have a variable effect on emissions of other GHGs, such as CO2 and CH4 [64, 65]. Sainju et al. [65] found that the application of 80 kg N ha<sup>1</sup> to dryland malt barley increased CO2 emissions, but not N2O and CH4 emissions (**Table 7**). Because N2O emissions has a large effect on net GWP and GHGI, practices that can reduce N fertilization rates without influencing crop yields can substantially reduce net GHG emissions [61, 62]. Other factors that can influence N2O emissions are the type, placement, time, and method of application of N fertilizers. Applying N fertilizer in the spring compared with autumn and using split application compared with one single application at planting can reduce N2O emissions in some cases [66]. Applying N fertilizer at various depths can have a variable effect on N2O emissions [67]. Anhydrous ammonia can increase N2O emissions compared with urea [67, 68]. Similarly, chemical additives to reduce nitrification from N fertilizers, such as polymer-coated urea and nitrification inhibitors, can substantially reduce N2O emissions compared with ordinary urea and non-nitrification inhibiting fertilizers [69]. Some N fertilizers, such as urea, emit both CO2 and N2O. Nitrogen fertilizers also indirectly emit N2O through NH3 volatilization and NO3-N leaching [68].

Increased N fertilization rate can enhance net GWP and GHGI due to increased N2O and CO2 emissions associated with the manufacture, transport, and application of N fertilizers, regardless of cropping systems and calculation methods [61, 70]. In a meta-analysis of 12 experiments, Sainju [71], after accounting for all sources and sinks of CO2 emissions, reported that net GWP decreased from 0 to ≤45 kg N ha<sup>1</sup> and net GHGI from 0 to ≤145 kg N ha<sup>1</sup> and then increased with increased N fertilization rate (**Figure 9**). Using partial accounting, net GWP decreased from 0 to 88 kg N ha<sup>1</sup> and net GHGI from 0 to ≤213 kg N ha<sup>1</sup> and then increased with increased N rate. These N rates probably corresponded to crop N demand when crops used most of the soil available N. The cropping systems that left little residual N in the soil reduced N2O emissions, and therefore net GWP and GHGI, whereas net GWP and GHGI increased linearly with increase in N application rates that exceeded crop N demand, suggesting that excessive N fertilizer applications can induce global warming. Similar results have been reported by Li et al. [44]. Therefore, N fertilizers should be applied at optimum rates to reduce net GWP and GHGI while sustaining crop yields. The optimum N rates, however, depended on net

GWP measured either per unit area or per unit crop yield.

*†*

**84**

*test.*

**Table 7.**

**N fertilization CO2 flux N2O flux CH4 flux kg N ha<sup>1</sup> Mg C ha<sup>1</sup> g N ha<sup>1</sup> g C ha<sup>1</sup>** <sup>0</sup> 1.15b† 308a 314a 80 1.23a 329a 291a

*Numbers followed by different letters within a column are significantly different at P ≤ 0.05 by the least square means*

*Effect of N fertilization on total soil surface greenhouse gas fluxes (from March to November) averaged across*

*years from 2008 to 2011 under rainfed malt barley in eastern Montana, USA [65].*

typically controls net GWP and GHGI [61, 62].

*Nitrogen Fixation*

*The relationship between N fertilization rate and net global warming potential (GWP) and greenhouse gas intensity (GHGI). Full accounting data denote calculations of GWP and GHGI by accounting all sources and sinks of CO2 (N2O and CH4 emissions, farm inputs, operations, and soil C sequestration). Partial accounting data denotes partial accounting of sources and sinks (N2O and CH4 emissions and/or soil C sequestration). All data denotes inclusions of full and partial accounting data [71].*

Sainju [71] observed that the relationships between net GWP, net GHGI, and N rate were further improved when the duration of the experiment and soil and climatic conditions were taken into account in the multiple linear regressions. Duration of experiment and annual precipitation had positive effects, but air temperature and soil texture had negative effects on net GWP when all sources and sinks of CO2 emissions were accounted for. With partial accounting, only air temperature had a positive effect on net GWP, but other factors had negative effects. For net GHGI, the factors having negative effects were air temperature using the complete accounting of CO2 emissions and annual precipitation and soil texture using the partial accounting. Sainju et al. [70] reported that net GWP and GHGI calculated from soil respiration and soil C sequestration methods were lower with 80 than 0 kg N ha<sup>1</sup> (**Table 8**). They noted that, although CO2 equivalents from N fertilization and soil respiration were higher with 80 kg N ha<sup>1</sup> , the amount of plant residue returned to the soil, soil C sequestration rate, and grain yields were greater


**Table 8.** *Net global warming potential (GWPR and GWPC) and greenhouse*

*and N fertilization*

 *rate in eastern Montana,*

 *USA [70].*

 *gas intensity (GHGIR and GHGIC) based on soil respiration*

 *and organic C (SOC) methods as influenced by cropping sequence* with 80 than 0 kg N ha

content from the desirable N rate.

**7. Conclusions**

**Author details**

Upendra M. Sainju

USA

**87**

1

Williston, North Dakota, USA

provided the original work is properly cited.

\*, Rajan Ghimire

Agricultural Research Service, Sidney, Montana, USA

\*Address all correspondence to: upendra.sainju@ars.usda.gov

 1

*DOI: http://dx.doi.org/10.5772/intechopen.86028*

*Nitrogen Fertilization I: Impact on Crop, Soil, and Environment*

fertilization than without, regardless of the method used for calculation.

Nitrogen fertilization is one of the most commonly used practice to increase crop yields throughout the world because of abundant availability of N fertilizers and their great effectiveness to increase yields compared with other organic fertilizers, such as manure and compost. Excessive application of N fertilizers in the last several decades, however, has resulted in undesirable consequences of soil and environmental degradations, such as soil acidification, N leaching to the groundwater, and greenhouse gas (N2O) emissions. Crop yields have declined in places where soil acidification is high due to unavailability of major nutrients and basic cations and toxic effect of acidic cations. Other disadvantages of excessive N fertilization include increased cost of fertilization, reduced N-use efficiency, and negative impact on human and livestock health. To reduce excessive N fertilization, composited soil sample to a depth of 60 cm should be conducted for NO

prior to crop planting and N fertilization rate be adjusted by deducting soil NO

<sup>2</sup> and Gautam P. Pradhan

1 Northern Plains Agricultural Research Laboratory, US Department of Agriculture,

2 Agricultural Science Center, New Mexico State University, Clovis, New Mexico,

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

3 Williston Research and Extension Center, North Dakota State University,

3

, thereby resulting in lower net GWP and GHGI with N

3-N test

3-N

#### *Nitrogen Fixation*

with 80 than 0 kg N ha<sup>1</sup> , thereby resulting in lower net GWP and GHGI with N fertilization than without, regardless of the method used for calculation.

## **7. Conclusions**

Nitrogen fertilization is one of the most commonly used practice to increase crop yields throughout the world because of abundant availability of N fertilizers and their great effectiveness to increase yields compared with other organic fertilizers, such as manure and compost. Excessive application of N fertilizers in the last several decades, however, has resulted in undesirable consequences of soil and environmental degradations, such as soil acidification, N leaching to the groundwater, and greenhouse gas (N2O) emissions. Crop yields have declined in places where soil acidification is high due to unavailability of major nutrients and basic cations and toxic effect of acidic cations. Other disadvantages of excessive N fertilization include increased cost of fertilization, reduced N-use efficiency, and negative impact on human and livestock health. To reduce excessive N fertilization, composited soil sample to a depth of 60 cm should be conducted for NO3-N test prior to crop planting and N fertilization rate be adjusted by deducting soil NO3-N content from the desirable N rate.

## **Author details**

Upendra M. Sainju<sup>1</sup> \*, Rajan Ghimire<sup>2</sup> and Gautam P. Pradhan<sup>3</sup>

1 Northern Plains Agricultural Research Laboratory, US Department of Agriculture, Agricultural Research Service, Sidney, Montana, USA

2 Agricultural Science Center, New Mexico State University, Clovis, New Mexico, USA

3 Williston Research and Extension Center, North Dakota State University, Williston, North Dakota, USA

\*Address all correspondence to: upendra.sainju@ars.usda.gov

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**Cropping**

**86**

**N rate**

 **Farm**

**N**

**Soil**

**N O flux 2**

**CH4**

**Annualized**

**residue (F)c**

 **crop**

**SOC**

**GWPR**

**GWPC**

**Annualized**

 **grain**

**GHGIR**

**GHGIC**

*Nitrogen Fixation*

**(K)g**

**(L)h**

**(G)d**

**(H)e**

**(I)f**

**yield (J)**

**kg ha1**

**kg CO2 kg1 grain**

**yield**

**fertilizer**

**respiration**

**(D)**

**flux (E)**

**(C)**

**(B)b**

**operation**

**(A)**

**kg N ha1 kg CO2**

> CTB-F

NTB-P

NTCB

182 124 124

0 80

*aCropping sequences are CTB-F,* 

*bTotal CO2* *cTotal above- and*  *dCarbon sequestration* *eColumn (H) = Column (A) + Column (B) + Column (C) + Column (D) + Column (E)*

*fColumn (I) = Column (A) + Column (B) + Column (D) + Column (E)*

*gColumn (K) = Column* 

*hColumn (L) = Column (I)/Column* *iNumbers followed by the same letters within a column in a set are not significantly*

**Table 8.** *Net global warming potential (GWPR and GWPC) and greenhouse*

*and N fertilization*

 *rate in eastern Montana,*

 *USA [70].*

*(H)/Column*

 *(J) [61]. Negative values indicate GHG sink.*

 *(J) [61]. Negative values indicate GHG sink.*

*equivalents from direct and indirect sources of N fertilization.*

*below-ground*

 *rate calculated from linear regression of change in soil organic C at the 0–10 cm depth from 2006 to 2011.*

 *crop residue.*

 143 *conventional-till*

 *malt* 

*barley-fallow;*

 *NTB-P, no-till malt barley-pea;*

 180

 3288a

 443a

15a

 5487a

 *and NTCB, no-till continuous malt barley.*

*Column (G) [61, 62]. Negative values indicate GHG sink.*

 *different at P ≤ 0.05.*

 *gas intensity (GHGIR and GHGIC) based on soil respiration*

 *and organic C (SOC) methods as influenced by cropping sequence*

*Column (F) [61]. Negative values indicate GHG sink.*

 566a

1448b

 185b

 1761a

0.82b

 0.11b

143

0

 3093b

 416a

16a

 4421b

 103

 3547a

 394a

15a

 5411a

 268b 94b

787a

 635a

 1399b

0.56a

 0.45a

1259b

 337b

 1683a

0.75b

 0.20b

91

 3303a

 469a

16a

 5980a

 554a

2005c

 115b

 1649a

1.22c

 0.07b

77

 2722bi

425a

16a

 3476b

114c

89a

 778a

 1408b

0.06a

 0.55a

**equivalent**

 **ha1 year1**

**sequencea**

## **References**

[1] Franzluebbers AJ. Integrated croplivestock systems in the southeastern USA. Agronomy Journal. 2007;**99**: 361-372

[2] Herrero M, Thorton PK, Notenbaert AM, Wood S, Masangi S, Freeman HA, et al. Smart investments in sustainable food productions: Revisiting mixed crop-livestock systems. Science. 2010; **327**:822-825

[3] Eickhout B, Bouwman AP, van Zeijts H. The role of nitrogen in world food production and environmental sustainability. Agriculture, Ecosystems and Environment. 2006;**116**:4-14

[4] Ross SM, Izaurralde RC, Janzen HH, Robertson JA, McGill WB. The nitrogen balance of three long-term agroecosystems on a boreal soil in western Canada. Agriculture, Ecosystems and Environment. 2008;**127**: 241-250

[5] Varvel GE, Peterson TA. Residual soil nitrogen as affected by continuous cropping, two-year, and four-year crop rotations. Agronomy Journal. 1990;**82**: 958-962

[6] Schepers JS, Mosier AR. Accounting for nitrogen in nonequilibrium soil-crop systems. In: Follett RF, editor. Managing Nitrogen for Groundwater Quality and Farm Profitability. Madison, WI: Soil Science Society of America; 1991. pp. 125-137

[7] Lenssen AW, Johnson GD, Carlson GR. Cropping sequence and tillage system influence annual crop production and water use in semiarid Montana. Field Crops Research. 2007; **100**:32-43

[8] Miller PR, McConkey B, Clayton GW, Brandt SA, Staricka JA, Johnston AM, et al. Pulse crop adaptation in the northern Great Plains. Agronomy Journal. 2002;**94**:261-272

[9] Sainju UM. Cropping sequence and nitrogen fertilization impact on surface residue, soil carbon sequestration, and crop yields. Agronomy Journal. 2014; **106**:1231-1242

[17] Boquet DJ, Hutchinson RL, Breitenbeck GA. Long-term tillage, cover crop, and nitrogen rate effects on cotton: Yield and fiber properties. Agronomy Journal. 2004;**96**:1436-1442

Journal. 2004;**96**:510-515

2001;**93**:157-163

2017;**210**:183-191

1363-1371

**89**

[19] Howard DD, Gwathmey CO, Essington ME, Roberts RK, Mullen MD. Nitrogen fertilization of no-till corn on loess-derived soils. Agronomy Journal.

[20] Sainju UM, Allen BL, Lenssen AW, Ghimire RP. Root biomass, root/shoot ratio, and soil water content under perennial grasses with different nitrogen rates. Field Crops Research.

[21] Vogel KP, Brejda JJ, Walters DT, Buxton DW. Switchgrass biomass production in the Midwest USA: Harvest and nitrogen management. Agronomy Journal. 2002;**94**:413-420

[22] Heggenstaller AH, Moore KJ, Liebman M, Anex RP. Nitrogen influences biomass and nutrient partitioning by perennial warm-season grasses. Agronomy Journal. 2009;**101**:

[23] Power JF. Seasonal changes in smooth bromegrass top and root growth

and fate of fertilizer nitrogen. Agronomy Journal. 1988;**80**:740-745

[24] Mahler RL, Harder RW. The influence of tillage methods, cropping

acidification of a northern Idaho soil.

[25] Schroder JL, Zhang H, Girma H, Raun WR, Penn CJ, Payton ME. Soil acidification from long-term use of

sequence, and N rates on the

Soil Science. 1984;**137**:52-60

[18] Sweeney DW, Moyer JL. In-season nitrogen uptake by grain sorghum following legume green manures in conservation tillage systems. Agronomy

*DOI: http://dx.doi.org/10.5772/intechopen.86028*

*Nitrogen Fertilization I: Impact on Crop, Soil, and Environment*

nitrogen fertilizers on winter wheat. Soil Science Society of America Journal.

[26] Liebig MA, Varvel GE, Doran JW, Wienhold BJ. Crop sequence and nitrogen fertilization effects on soil properties in the western Corn Belt. Soil Science Society of America Journal.

[27] Sainju UM, Allen BL, Caesar-TonThat T, Lenssen AW. Dryland soil chemical properties and crop yields affected by long-term tillage and cropping sequence. Springerplus. 2015; **4**:230. DOI: 10.1186/s40064-015-1122-4

[28] Aase JK, Aase JK, Pikul JL Jr. Crop and soil responses to long-term tillage practices in the northern Great Plains. Agronomy Journal. 1995;**87**:

[29] Ghimire R, Machado S, Bista P. Soil pH, soil organic matter, and crop yields

[30] Guo JH, Liu XJ, Zhang Y, Shen JL, Han WX, Zhang WF. Significant acidification in major Chinese

croplands. Science. 2010;**327**:1008-1010

[31] Rasmussen PE, Rhode CR. Soil acidification from ammonium-nitrogen fertilization in moldboard plow and stubble mulch tillage in wheat-fallow system. Soil Science Society of America

[32] Lilienfein J, Wilcke W, Vilele L, Lima SD, Thomas R, Zech W. Effect of no-till and conventional tillage systems on the chemical composition of soils solid phase and soil solution of Brazilian Savanna soils. Journal of Plant Nutrition and Soil Science. 2000;**163**:411-419

[33] Zibilske LM, Bradford JM, Smart JR. Conservation tillage-induced changes in

Journal. 1989;**53**:119-122

in winter wheat-summer fallow systems. Agronomy Journal. 2017;**109**:

2011;**75**:957-964

2002;**66**:596-601

652-656

706-717

[10] Sainju UM, Lenssen AW, Barsotti JL. Dryland malt barley yield and quality affected by tillage, cropping sequence, and nitrogen fertilization. Agronomy Journal. 2013;**105**:329-340

[11] Halvorson AD, Reule CA. Irrigated, no-till corn and barley response to nitrogen in northern Colorado. Agronomy Journal. 2007;**99**:1521-1529

[12] O' Donovan JT, Turkington TK, Edney MJ, Clayton GW, McKenzie RH, Juskiew PE, et al. Seeding rate, nitrogen rate, and cultivar effects on malting barley production. Agronomy Journal. 2011;**103**:709-716

[13] Birch CJ, Long KE. Effect of nitrogen on the growth, yield, and grain protein content of barley. Australian Journal of Experimental Agriculture. 1990;**30**:237-242

[14] Weston DT, Horsley RD, Schwarz PB, Goos RJ. Nitrogen and planting effects on low-protein spring barley. Agronomy Jpornal. 1993;**85**:1170-1174

[15] Thompson TL, Ottman MJ, Riley-Saxton E. Basal stem nitrate tests for irrigating malt barley. Agronomy Journal. 2004;**86**:516-524

[16] Sainju UM, Singh BP, Whitehead WF, Wang S. Tillage, cover crop, and nitrogen fertilization effect on soil nitrogen and cotton and sorghum yields. European Journal of Agronomy. 2006; **25**:372-382

*Nitrogen Fertilization I: Impact on Crop, Soil, and Environment DOI: http://dx.doi.org/10.5772/intechopen.86028*

[17] Boquet DJ, Hutchinson RL, Breitenbeck GA. Long-term tillage, cover crop, and nitrogen rate effects on cotton: Yield and fiber properties. Agronomy Journal. 2004;**96**:1436-1442

**References**

*Nitrogen Fixation*

361-372

**327**:822-825

241-250

958-962

pp. 125-137

**100**:32-43

**88**

[1] Franzluebbers AJ. Integrated croplivestock systems in the southeastern USA. Agronomy Journal. 2007;**99**:

northern Great Plains. Agronomy

[9] Sainju UM. Cropping sequence and nitrogen fertilization impact on surface residue, soil carbon sequestration, and crop yields. Agronomy Journal. 2014;

[10] Sainju UM, Lenssen AW, Barsotti JL. Dryland malt barley yield and quality affected by tillage, cropping sequence, and nitrogen fertilization. Agronomy

[11] Halvorson AD, Reule CA. Irrigated, no-till corn and barley response to nitrogen in northern Colorado. Agronomy Journal. 2007;**99**:1521-1529

[12] O' Donovan JT, Turkington TK, Edney MJ, Clayton GW, McKenzie RH, Juskiew PE, et al. Seeding rate, nitrogen rate, and cultivar effects on malting barley production. Agronomy Journal.

[13] Birch CJ, Long KE. Effect of

nitrogen on the growth, yield, and grain protein content of barley. Australian Journal of Experimental Agriculture.

[14] Weston DT, Horsley RD, Schwarz PB, Goos RJ. Nitrogen and planting effects on low-protein spring barley. Agronomy Jpornal. 1993;**85**:1170-1174

[15] Thompson TL, Ottman MJ, Riley-Saxton E. Basal stem nitrate tests for irrigating malt barley. Agronomy

[16] Sainju UM, Singh BP, Whitehead WF, Wang S. Tillage, cover crop, and nitrogen fertilization effect on soil nitrogen and cotton and sorghum yields. European Journal of Agronomy. 2006;

Journal. 2004;**86**:516-524

**25**:372-382

Journal. 2002;**94**:261-272

Journal. 2013;**105**:329-340

2011;**103**:709-716

1990;**30**:237-242

**106**:1231-1242

[2] Herrero M, Thorton PK, Notenbaert AM, Wood S, Masangi S, Freeman HA, et al. Smart investments in sustainable food productions: Revisiting mixed crop-livestock systems. Science. 2010;

[3] Eickhout B, Bouwman AP, van Zeijts H. The role of nitrogen in world food production and environmental

sustainability. Agriculture, Ecosystems and Environment. 2006;**116**:4-14

[4] Ross SM, Izaurralde RC, Janzen HH, Robertson JA, McGill WB. The nitrogen

Ecosystems and Environment. 2008;**127**:

[5] Varvel GE, Peterson TA. Residual soil nitrogen as affected by continuous cropping, two-year, and four-year crop rotations. Agronomy Journal. 1990;**82**:

[6] Schepers JS, Mosier AR. Accounting for nitrogen in nonequilibrium soil-crop systems. In: Follett RF, editor. Managing Nitrogen for Groundwater Quality and Farm Profitability. Madison, WI: Soil Science Society of America; 1991.

[7] Lenssen AW, Johnson GD, Carlson GR. Cropping sequence and tillage system influence annual crop

production and water use in semiarid Montana. Field Crops Research. 2007;

[8] Miller PR, McConkey B, Clayton GW, Brandt SA, Staricka JA, Johnston AM, et al. Pulse crop adaptation in the

balance of three long-term agroecosystems on a boreal soil in western Canada. Agriculture,

[18] Sweeney DW, Moyer JL. In-season nitrogen uptake by grain sorghum following legume green manures in conservation tillage systems. Agronomy Journal. 2004;**96**:510-515

[19] Howard DD, Gwathmey CO, Essington ME, Roberts RK, Mullen MD. Nitrogen fertilization of no-till corn on loess-derived soils. Agronomy Journal. 2001;**93**:157-163

[20] Sainju UM, Allen BL, Lenssen AW, Ghimire RP. Root biomass, root/shoot ratio, and soil water content under perennial grasses with different nitrogen rates. Field Crops Research. 2017;**210**:183-191

[21] Vogel KP, Brejda JJ, Walters DT, Buxton DW. Switchgrass biomass production in the Midwest USA: Harvest and nitrogen management. Agronomy Journal. 2002;**94**:413-420

[22] Heggenstaller AH, Moore KJ, Liebman M, Anex RP. Nitrogen influences biomass and nutrient partitioning by perennial warm-season grasses. Agronomy Journal. 2009;**101**: 1363-1371

[23] Power JF. Seasonal changes in smooth bromegrass top and root growth and fate of fertilizer nitrogen. Agronomy Journal. 1988;**80**:740-745

[24] Mahler RL, Harder RW. The influence of tillage methods, cropping sequence, and N rates on the acidification of a northern Idaho soil. Soil Science. 1984;**137**:52-60

[25] Schroder JL, Zhang H, Girma H, Raun WR, Penn CJ, Payton ME. Soil acidification from long-term use of

nitrogen fertilizers on winter wheat. Soil Science Society of America Journal. 2011;**75**:957-964

[26] Liebig MA, Varvel GE, Doran JW, Wienhold BJ. Crop sequence and nitrogen fertilization effects on soil properties in the western Corn Belt. Soil Science Society of America Journal. 2002;**66**:596-601

[27] Sainju UM, Allen BL, Caesar-TonThat T, Lenssen AW. Dryland soil chemical properties and crop yields affected by long-term tillage and cropping sequence. Springerplus. 2015; **4**:230. DOI: 10.1186/s40064-015-1122-4

[28] Aase JK, Aase JK, Pikul JL Jr. Crop and soil responses to long-term tillage practices in the northern Great Plains. Agronomy Journal. 1995;**87**: 652-656

[29] Ghimire R, Machado S, Bista P. Soil pH, soil organic matter, and crop yields in winter wheat-summer fallow systems. Agronomy Journal. 2017;**109**: 706-717

[30] Guo JH, Liu XJ, Zhang Y, Shen JL, Han WX, Zhang WF. Significant acidification in major Chinese croplands. Science. 2010;**327**:1008-1010

[31] Rasmussen PE, Rhode CR. Soil acidification from ammonium-nitrogen fertilization in moldboard plow and stubble mulch tillage in wheat-fallow system. Soil Science Society of America Journal. 1989;**53**:119-122

[32] Lilienfein J, Wilcke W, Vilele L, Lima SD, Thomas R, Zech W. Effect of no-till and conventional tillage systems on the chemical composition of soils solid phase and soil solution of Brazilian Savanna soils. Journal of Plant Nutrition and Soil Science. 2000;**163**:411-419

[33] Zibilske LM, Bradford JM, Smart JR. Conservation tillage-induced changes in

organic carbon, total nitrogen, and available phosphorus in a semi-arid alkaline subtropical soil. Soil and Tillage Research. 2002;**66**:153-163

[34] Tarkalson DD, Hergert GW, Cassman KG. Long-term effects of tillage on soil chemical properties and grain yields of a dryland winter wheatsorghum/corn-fallow rotation in the Great Plains. Agronomy Journal. 2006; **98**:26-33

[35] Darusman L, Stone R, Whitney DA, Janssen KA, Long JH. Soil properties after twenty years of fertilization with different nitrogen sources. Soil Science Society of America Journal. 1991;**55**: 1097-1100

[36] Halvorson AD, Black AL, Krupinsky JM, Merrill SD. Dryland winter wheat response to tillage and nitrogen within an annual cropping system. Agronomy Journal. 1999;**91**:702-707

[37] Russell AE, Laird DA, Parkin TB, Mallarino AP. Impact of nitrogen fertilization and cropping system on carbon sequestration in Midwestern mollisols. Soil Science Society of America Journal. 2005;**69**:413-422

[38] Omay AB, Rice CW, Maddux LD, Gordon WB. Changes in soil microbial and chemical properties under longterm crop rotation and fertilization. Soil Science Society of America Journal. 1997;**61**:1672-1678

[39] Sainju UM, Whitehead WF, Singh BP. Carbon accumulation in cotton, sorghum, and underlying soil as influenced by tillage, cover crops, and nitrogen fertilization. Plant and Soil. 2005;**273**:219-234

[40] Ma Z, Wood C, Bransby DI. Impacts of soil management on root characteristics of switchgrass. Biomass and Bioenergy. 2000;**18**:105-112

[41] Santori F, Lal R, Ebinger MH, Parrish DJ. Potential soil carbon

sequestration and CO2 offset by dedicated energy crops in the USA. Critical Reviews in Plant Sciences. 2006; **25**:441-472

Quebec soils. Journal of Environmental

*DOI: http://dx.doi.org/10.5772/intechopen.86028*

*Nitrogen Fertilization I: Impact on Crop, Soil, and Environment*

Follett RF, editor. Nitrogen Management and Groundwater

pp. 35-74

Protection. Amsterdam: Elsevier; 1989.

[57] Timmons DR, Dylla AS. Nitrogen leaching as influenced by nitrogen management and supplemental irrigation level. Journal of

Environmental Quality. 1981;**10**:421-426

[58] Pang XP, Gupta SC, Moncrief JF, Rosen CJ, Cheng HH. Evaluation of nitrate leaching potential on Minnesota glacial outwash soils using the CERESmaize model. Journal of Environmental

Quality. 1998;**27**:75-85

[59] Meisinger JJ, Hargrove WL, Mikkelsen RI Jr, Williams JR, Benson

groundwater quality. In: Hargrove WL, editor. Cover crops for clean water. Ankeny, Iowa, USA: Soil and Water Conservation Society; 1991. pp. 57-68

[60] Intergovernment Panel on Climate Change (IPCC). Climate change 2014: Synthesis report. Contribution of working groups I, II and III to the fifth

Intergovernmental Panel on Climate Change. Geneva, Switzerland: IPCC;

[61] Mosier AR, Halvorson AD, Reule CA, Liu XJ. Net global warming potential and greenhouse gas intensity in irrigated cropping systems in northeastern Colorado. Journal of Environmental Quality. 2006;**35**:

[62] Robertson GP, Paul E, Harwood R.

agriculture: Contribution of individual gases to the radiative forcing of the atmosphere. Science. 2000;**289**:

[63] West TO, Marland G. A synthesis of carbon sequestration, carbon emissions, and net carbon flux in agriculture:

Greenhouse gases in intensive

VE. Effects of cover crops on

assessment report of the

2014

1584-1598

1922-1925

[49] Keeney DR, Follett RF. Overview and introduction. In: Follett RF, editor. Managing Nitrogen for Groundwater Quality and Farm Profitability. Soil Science Society of America, Madison. USA: Wisconsin; 1991. pp. 1-3

[50] Yadav SN. Formulation and estimation of nitrate-nitrogen leaching from corn cultivation. Journal of Environmental Quality. 1997;**26**:

[51] Sainju UM, Lenssen AW, Allen BL, Stevens WB, Jabro JD. Nitrogen balance in response to dryland crop rotations and cultural practices. Agriculture, Ecosystems and Environment. 2016;**233**:

[52] Zibilske LM, Bradford JM, Smart JR. Conservation tillage-induced changes in organic carbon, total nitrogen, and available phosphorus in a semi-arid alkaline subtropical soil. Soil and Tillage

Opportunities for meeting crop nitrogen needs from symbiotic nitrogen fixation.

[54] Wood CW, Westfall DG, Peterson GA, Burke IC. Impacts of cropping intensity on carbon and nitrogen mineralization under no-till

agroecosystems. Agronomy Journal.

[55] Sainju UM. Tillage, cropping sequence, and nitrogen fertilization influence dryland soil nitrogen.

[56] Hallberg GR. Nitrate in

Agronomy Journal. 2013;**105**:1253-1263

groundwater in the United States. In:

Research. 2002;**66**:153-163

[53] Heichel GH, Barnes DK.

In: Bezdicek DF, editor. Organic Farming: Current Technology and its Role in Sustainable Agriculture (Special Publication 46). Madison, WI: Soil Science Society of America; 1984.

808-814

25-32

pp. 49-59

**91**

1990;**82**:1115-1120

Quality. 1994;**23**:521-525

[42] Bremer E, Janzen HH, Ellert BH, McKenzie RH. Soil organic carbon after twelve years of various crop rotations in an aridic boroll. Soil Science Society of America Journal. 2007;**72**:970-974

[43] Rice CW. Soil organic carbon and nitrogen in rangeland soil under elevated carbon dioxide and land management. In: Proceedings of the Advances in Terrestrial Ecosystem and Carbon Inventory, Measurement, and Monitoring; 3–5 October 2000; Washington, DC. Beltsville. Maryland. USA: USDA-ARS; 2000

[44] Li B, Fan CH, Zhang H, Chen ZZ, Sun LY, Xiong ZQ. Combined effects of nitrogen fertilization and biochar on the net global warming potential, greenhouse gas intensity, and net ecosystem budget in intensive vegetable agriculture in southeastern China. Agriculture, Ecosystems and Environment. 2015;**100**:10-19

[45] Sainju UM, Allen BL, Lenssen AW, Mikha M. Root and soil total carbon and nitrogen under bioenergy perennial grasses with various nitrogen rates. Biomass and Bioenergy. 2017;**107**: 326-334

[46] Sainju UM, Singh BP. Nitrogen storage with cover crops and nitrogen fertilization in tilled and non-tilled soils. Agronomy Journal. 2008;**100**:619-627

[47] Sainju UM, Singh BP, Rahman S, Reddy VR. Soil nitrate-nitrogen under tomato following tillage, cover cropping, and nitrogen fertilization. Journal of Environmental Quality. 1999; **28**:1837-1844

[48] Liang BC, McKenzie AF. Changes of soil nitrate-nitrogen and denitrification as affected by nitrogen fertilizer on two

*Nitrogen Fertilization I: Impact on Crop, Soil, and Environment DOI: http://dx.doi.org/10.5772/intechopen.86028*

Quebec soils. Journal of Environmental Quality. 1994;**23**:521-525

organic carbon, total nitrogen, and available phosphorus in a semi-arid alkaline subtropical soil. Soil and Tillage sequestration and CO2 offset by dedicated energy crops in the USA. Critical Reviews in Plant Sciences. 2006;

[42] Bremer E, Janzen HH, Ellert BH, McKenzie RH. Soil organic carbon after twelve years of various crop rotations in an aridic boroll. Soil Science Society of America Journal. 2007;**72**:970-974

[43] Rice CW. Soil organic carbon and nitrogen in rangeland soil under elevated carbon dioxide and land management. In: Proceedings of the Advances in Terrestrial Ecosystem and Carbon Inventory, Measurement, and Monitoring; 3–5 October 2000;

Washington, DC. Beltsville. Maryland.

[44] Li B, Fan CH, Zhang H, Chen ZZ, Sun LY, Xiong ZQ. Combined effects of nitrogen fertilization and biochar on the

[45] Sainju UM, Allen BL, Lenssen AW, Mikha M. Root and soil total carbon and nitrogen under bioenergy perennial grasses with various nitrogen rates. Biomass and Bioenergy. 2017;**107**:

[46] Sainju UM, Singh BP. Nitrogen storage with cover crops and nitrogen fertilization in tilled and non-tilled soils. Agronomy Journal. 2008;**100**:619-627

[47] Sainju UM, Singh BP, Rahman S, Reddy VR. Soil nitrate-nitrogen under

[48] Liang BC, McKenzie AF. Changes of soil nitrate-nitrogen and denitrification as affected by nitrogen fertilizer on two

tomato following tillage, cover cropping, and nitrogen fertilization. Journal of Environmental Quality. 1999;

USA: USDA-ARS; 2000

326-334

**28**:1837-1844

net global warming potential, greenhouse gas intensity, and net ecosystem budget in intensive vegetable agriculture in southeastern China. Agriculture, Ecosystems and Environment. 2015;**100**:10-19

**25**:441-472

[34] Tarkalson DD, Hergert GW, Cassman KG. Long-term effects of tillage on soil chemical properties and grain yields of a dryland winter wheatsorghum/corn-fallow rotation in the Great Plains. Agronomy Journal. 2006;

[35] Darusman L, Stone R, Whitney DA, Janssen KA, Long JH. Soil properties after twenty years of fertilization with different nitrogen sources. Soil Science Society of America Journal. 1991;**55**:

[36] Halvorson AD, Black AL, Krupinsky JM, Merrill SD. Dryland winter wheat response to tillage and nitrogen within an annual cropping system. Agronomy

[37] Russell AE, Laird DA, Parkin TB, Mallarino AP. Impact of nitrogen fertilization and cropping system on carbon sequestration in Midwestern mollisols. Soil Science Society of America Journal. 2005;**69**:413-422

[38] Omay AB, Rice CW, Maddux LD, Gordon WB. Changes in soil microbial and chemical properties under longterm crop rotation and fertilization. Soil Science Society of America Journal.

[39] Sainju UM, Whitehead WF, Singh BP. Carbon accumulation in cotton, sorghum, and underlying soil as influenced by tillage, cover crops, and nitrogen fertilization. Plant and Soil.

[40] Ma Z, Wood C, Bransby DI. Impacts of soil management on root characteristics of switchgrass. Biomass and Bioenergy. 2000;**18**:105-112

[41] Santori F, Lal R, Ebinger MH, Parrish DJ. Potential soil carbon

Journal. 1999;**91**:702-707

1997;**61**:1672-1678

2005;**273**:219-234

**90**

Research. 2002;**66**:153-163

*Nitrogen Fixation*

**98**:26-33

1097-1100

[49] Keeney DR, Follett RF. Overview and introduction. In: Follett RF, editor. Managing Nitrogen for Groundwater Quality and Farm Profitability. Soil Science Society of America, Madison. USA: Wisconsin; 1991. pp. 1-3

[50] Yadav SN. Formulation and estimation of nitrate-nitrogen leaching from corn cultivation. Journal of Environmental Quality. 1997;**26**: 808-814

[51] Sainju UM, Lenssen AW, Allen BL, Stevens WB, Jabro JD. Nitrogen balance in response to dryland crop rotations and cultural practices. Agriculture, Ecosystems and Environment. 2016;**233**: 25-32

[52] Zibilske LM, Bradford JM, Smart JR. Conservation tillage-induced changes in organic carbon, total nitrogen, and available phosphorus in a semi-arid alkaline subtropical soil. Soil and Tillage Research. 2002;**66**:153-163

[53] Heichel GH, Barnes DK. Opportunities for meeting crop nitrogen needs from symbiotic nitrogen fixation. In: Bezdicek DF, editor. Organic Farming: Current Technology and its Role in Sustainable Agriculture (Special Publication 46). Madison, WI: Soil Science Society of America; 1984. pp. 49-59

[54] Wood CW, Westfall DG, Peterson GA, Burke IC. Impacts of cropping intensity on carbon and nitrogen mineralization under no-till agroecosystems. Agronomy Journal. 1990;**82**:1115-1120

[55] Sainju UM. Tillage, cropping sequence, and nitrogen fertilization influence dryland soil nitrogen. Agronomy Journal. 2013;**105**:1253-1263

[56] Hallberg GR. Nitrate in groundwater in the United States. In: Follett RF, editor. Nitrogen Management and Groundwater Protection. Amsterdam: Elsevier; 1989. pp. 35-74

[57] Timmons DR, Dylla AS. Nitrogen leaching as influenced by nitrogen management and supplemental irrigation level. Journal of Environmental Quality. 1981;**10**:421-426

[58] Pang XP, Gupta SC, Moncrief JF, Rosen CJ, Cheng HH. Evaluation of nitrate leaching potential on Minnesota glacial outwash soils using the CERESmaize model. Journal of Environmental Quality. 1998;**27**:75-85

[59] Meisinger JJ, Hargrove WL, Mikkelsen RI Jr, Williams JR, Benson VE. Effects of cover crops on groundwater quality. In: Hargrove WL, editor. Cover crops for clean water. Ankeny, Iowa, USA: Soil and Water Conservation Society; 1991. pp. 57-68

[60] Intergovernment Panel on Climate Change (IPCC). Climate change 2014: Synthesis report. Contribution of working groups I, II and III to the fifth assessment report of the Intergovernmental Panel on Climate Change. Geneva, Switzerland: IPCC; 2014

[61] Mosier AR, Halvorson AD, Reule CA, Liu XJ. Net global warming potential and greenhouse gas intensity in irrigated cropping systems in northeastern Colorado. Journal of Environmental Quality. 2006;**35**: 1584-1598

[62] Robertson GP, Paul E, Harwood R. Greenhouse gases in intensive agriculture: Contribution of individual gases to the radiative forcing of the atmosphere. Science. 2000;**289**: 1922-1925

[63] West TO, Marland G. A synthesis of carbon sequestration, carbon emissions, and net carbon flux in agriculture:

Comparing tillage practices in the United States. Agriculture, Ecosystems and Environment. 2002;**91**:217-232

[64] Bronson KF, Mosier AR. Suppression of methane oxidation in aerobic soil by nitrogen fertilizers, nitrification inhibitors, and urease inhibitors. Biology and Fertility of Soils. 1994;**17**:263-268

[65] Sainju UM, Caesar-TonThat T, Lenssen AW, Barsotti JL. Dryland soil greenhouse gas emissions affected by cropping sequence and nitrogen fertilization. Soil Science Society of America Journal. 2012;**76**:1741-1757

[66] Phillips RL, Tanaka DL, Archer DW, Hanson JD. Fertilizer application timing influences greenhouse gas fluxes over a growing season. Journal of Environmental Quality. 2009;**38**: 1569-1579

[67] Fujinuma R, Venterea RT, Rosen C. Broadcast urea reduces N2O but increases NO emissions compared with conventional and shallow applied anhydrous ammonia in a coarsetextured soil. Journal of Environmental Quality. 2011;**40**:1806-1815

[68] Venterea RT, Burger M, Spokas KA. Nitrogen oxide and methane emissions under varying tillage and fertilizer management. Journal of Environmental Quality. 2005;**34**:1467-1477

[69] Halvorson AD, Del Grosso SJ, Alluvione F. Nitrogen source effects on nitrous oxide emissions from irrigated no-till corn. Journal of Environmental Quality. 2010;**39**:1554-1562

[70] Sainju UM, Wang J, Barsotti JL. Net global warming potential and greenhouse gas intensity affected by cropping sequence and nitrogen fertilization. Soil Science Society of America Journal. 2013;**78**:248-261

[71] Sainju UM. A global meta-analysis on the impact of management practices on net global warming potential and greenhouse intensity from cropland soils. PLoS One. 2016;**11**(2):1/26-26/26. DOI: 10.137/journal.pone 0148527

**93**

**Chapter 6**

**Abstract**

need to be clarified.

volatilization

**1. Introduction**

sure and high temperature [1].

Advancement of Nitrogen

*Izabelle Pereira Andrade and Letícia Faria Abreu*

*Elaine Maria Silva Guedes Lobato, Beatriz Martineli Lima,* 

*Barbara Rodrigues Quadros, Allan Klynger da Silva Lobato,* 

The nitrogen (N) fertilization synthetic or biological is primordial for food production worldwide. The consumption of N fertilizers in agricultural systems increased in exponential scale, mainly in developing countries. However, some negative points are associated to industrial N consumption; consequently the industry promoted ways to minimize N losses in production systems of tropical agriculture. Biological nitrogen fixation is a very important natural and sustainable process for the growth of leguminous plants, in which many micronutrients are involved, mainly as enzyme activators or prosthetic group. However, other mechanisms in the rhizosphere and molecular region still need to be clarified. Therefore, the aim of this chapter is to compile information about the historical and current affairs about the advances in N fertilization in tropical environments through a history from N fertilization worldwide, N balance in the main agricultural systems, introduction of alternative ways to avoid N losses, advances between BNF and micronutrients, as well as the effects of N absence in plant metabolisms. Biological nitrogen fixation is a very important natural process for the growth of leguminous plants, in addition many metallic nutrients, micronutrients, are involved in BNF metabolism, mainly as enzyme activators or prosthetic group. But other mechanisms in the rhizosphere and molecular region still

**Keywords:** ammonia synthesis, biological N fixation, humic substances, N balance,

Hellriegel and Wilfarth showed definitive evidence for N2 fixation by microbes in legumes in 1886, but the industrial process to fertilizer production known as the Haber-Bosch was established just in 1906, which uses a catalytic agent at high pres-

Actually, the world population has now been increasingly relying on nitrogen (N) fertilizers in order to keep up with the demands of food and economic growth rates; on the other hand, less than 30% of synthetic fertilizers would actually be

Fertilization on Tropical

Environmental

*Elizeu Monteiro Pereira Junior,* 

#### **Chapter 6**

Comparing tillage practices in the United States. Agriculture, Ecosystems and Environment. 2002;**91**:217-232

[71] Sainju UM. A global meta-analysis on the impact of management practices on net global warming potential and greenhouse intensity from cropland soils. PLoS One. 2016;**11**(2):1/26-26/26. DOI: 10.137/journal.pone 0148527

Suppression of methane oxidation in aerobic soil by nitrogen fertilizers, nitrification inhibitors, and urease inhibitors. Biology and Fertility of Soils.

[65] Sainju UM, Caesar-TonThat T, Lenssen AW, Barsotti JL. Dryland soil greenhouse gas emissions affected by cropping sequence and nitrogen fertilization. Soil Science Society of America Journal. 2012;**76**:1741-1757

[66] Phillips RL, Tanaka DL, Archer DW, Hanson JD. Fertilizer application timing influences greenhouse gas fluxes over a growing season. Journal of Environmental Quality. 2009;**38**:

[67] Fujinuma R, Venterea RT, Rosen C.

[68] Venterea RT, Burger M, Spokas KA. Nitrogen oxide and methane emissions under varying tillage and fertilizer management. Journal of Environmental

Broadcast urea reduces N2O but increases NO emissions compared with conventional and shallow applied anhydrous ammonia in a coarsetextured soil. Journal of Environmental

Quality. 2011;**40**:1806-1815

Quality. 2005;**34**:1467-1477

Quality. 2010;**39**:1554-1562

global warming potential and greenhouse gas intensity affected by cropping sequence and nitrogen fertilization. Soil Science Society of America Journal. 2013;**78**:248-261

**92**

[69] Halvorson AD, Del Grosso SJ, Alluvione F. Nitrogen source effects on nitrous oxide emissions from irrigated no-till corn. Journal of Environmental

[70] Sainju UM, Wang J, Barsotti JL. Net

[64] Bronson KF, Mosier AR.

1994;**17**:263-268

*Nitrogen Fixation*

1569-1579
