**2. Materials and methods**

### **2.1. Site description**

Field trial was conducted to investigate effects of AM (poultry, cattle, and sheep manures) and phosphorus levels (40, 80, 120, and 160 kg P2O5 ha−1) on growth and yield of maize with (+) and without (−) PSB at the Agronomy Research Farm of The University of Agriculture Peshawar, during summer 2014. The experimental farm is located at 34.01°N latitude, 71.35°E longitude at an altitude of 350 m above sea level. The farm soil is silt clay loam, low in organic matter (0.87%), extractable P (5.6 mg P kg−1), exchangeable, alkaline (pH 8.2), and calcareous in nature [9].

### **2.2. Experimentation**

The experiment was laid out in randomized complete block design with split plot arrangement using three replications. Combinations of three AM and to PSB levels (with and without PSB) were applied to the main plots, whereas four phosphorus (P) levels were applied to subplots. All the AM sources (poultry manure, sheep manure, and cattle manure) were applied at the rate of 5 t ha−1 2 weeks before seed bed preparation, while P was applied at sowing time. The PSB obtained from NARC, Islamabad, was mixed with the seed just before sowing time. A subplot size of 4 m × 3.5 m, having five rows, 4 m long, and 70 cm apart was used. A uniform dose of 120 kg N ha−1 as urea in two equal splits, that is, half at sowing, and half at knee height was applied. Maize hybrid "CS-200" was used as a test crop. All other agronomic practices were kept uniform and normal for all the treatments.

#### **2.3. Data recording**

Data on ear length (cm) were recorded with the help of meter rod by selecting ten plants randomly from each subplot, and then, the average was worked out. Number of grains ear−1 was calculated on 10 randomly selected ears from each subplot, and then, average was worked out. Thousand grain weights (g) of randomly 1000 grains were taken from seed lot of each subplot and were weighted with the help of electronic balance. For grain yield data, the three central rows of each treatment were harvested, dried, threshed, weighted, and then were converted into grain yield (kg ha−1) using following formula:

Integrated Use of Phosphorus, Animal Manures and Biofertilizers Improve Maize Productivity under Semiarid Condition http://dx.doi.org/10.5772/62388 141

( ) ( ) <sup>1</sup> Grains weight in three rows kg <sup>2</sup> Grain yield kg ha 10,000 m No. of rows row length R – R distance - = ´ ´ ´

Harvest index and shelling percentage for each treatment were calculated using the following formulae.

> Economic yield Harvest index <sup>100</sup> Biological yield = ´

$$\text{Shelling } \%= \frac{\text{Grains weight of 10 ears}}{\text{Total weight of 10 ears}} \times 1000$$

#### **2.4. Statistical analysis**

out suitable AM source, (2) to find out proper P level, (3) to find out proper combination of AM × P, (4) to find out proper combination of AM × PSB, (5) to find out proper combination of P × PSB, and (6) to find out proper combination of AM × PSB × P for improving yield and yield components of maize hybrid (CS200) under the semiarid condition at Peshawar (Paki‐

Field trial was conducted to investigate effects of AM (poultry, cattle, and sheep manures) and phosphorus levels (40, 80, 120, and 160 kg P2O5 ha−1) on growth and yield of maize with (+) and without (−) PSB at the Agronomy Research Farm of The University of Agriculture Peshawar, during summer 2014. The experimental farm is located at 34.01°N latitude, 71.35°E longitude at an altitude of 350 m above sea level. The farm soil is silt clay loam, low in organic matter (0.87%), extractable P (5.6 mg P kg−1), exchangeable, alkaline (pH 8.2), and calcareous

The experiment was laid out in randomized complete block design with split plot arrangement using three replications. Combinations of three AM and to PSB levels (with and without PSB) were applied to the main plots, whereas four phosphorus (P) levels were applied to subplots. All the AM sources (poultry manure, sheep manure, and cattle manure) were applied at the rate of 5 t ha−1 2 weeks before seed bed preparation, while P was applied at sowing time. The PSB obtained from NARC, Islamabad, was mixed with the seed just before sowing time. A subplot size of 4 m × 3.5 m, having five rows, 4 m long, and 70 cm apart was used. A uniform dose of 120 kg N ha−1 as urea in two equal splits, that is, half at sowing, and half at knee height was applied. Maize hybrid "CS-200" was used as a test crop. All other agronomic practices

Data on ear length (cm) were recorded with the help of meter rod by selecting ten plants randomly from each subplot, and then, the average was worked out. Number of grains ear−1 was calculated on 10 randomly selected ears from each subplot, and then, average was worked out. Thousand grain weights (g) of randomly 1000 grains were taken from seed lot of each subplot and were weighted with the help of electronic balance. For grain yield data, the three central rows of each treatment were harvested, dried, threshed, weighted, and then were

stan).

**2. Materials and methods**

140 Organic Fertilizers - From Basic Concepts to Applied Outcomes

**2.1. Site description**

in nature [9].

**2.2. Experimentation**

**2.3. Data recording**

were kept uniform and normal for all the treatments.

converted into grain yield (kg ha−1) using following formula:

Data were statistically analyzed according to [44] for randomized complete block design with split plot arrangement, and means among different treatments were compared using least significant differences (LSD) test (p ≤ 0.05).

### **3. Results and discussion**

#### **3.1. Effect of phosphorus**

Phosphorus (P) levels significantly affected ear length, number of grains ear−1, thousand grains weight, grain yield, harvest index, and shelling percentage of maize (**Table 1**). Higher ear length (25 cm) was obtained with the application of P at the rate of 120 kg ha−1, followed by 160 kg P ha−1 (23 cm), whereas lower ear length (20 cm) was produced in plots receiving 40 kg P ha−1. The higher number of grains ear−1 (417) was obtained at 120 kg P ha−1, followed by 160 kg P ha−1 (406), whereas lower number of grains ear−1 (385) was recorded with 40 kg P ha−1. Phosphorus application at the rate of 120 kg P ha−1 produced heavier thousand grains weight (346.5 g) being statistically at par with 160 kg P ha−1 (347.8 g), while the lower thousand grains weight (331.2 g) was recorded with 40 kg P ha−1. The highest grain yield (5245 kg ha−1) was obtained with the highest P level of 160 kg P ha−1 being at par with 120 kg P ha−1 (5164 kg ha−1). The lowest grain yield (4284 kg ha−1) was noted in the plot received the lowest rate of 40 kg P ha−1. Application of 160 kg P ha−1 resulted in the highest harvest index (42.13%) being statisti‐ cally at par with 120 and 80 kg P ha−1, while plots with 40 kg P ha−1 resulted in the lower harvest index (38.49%). The higher shelling percentage (83.6%) was calculated with 120 kg P ha−1; however, it was statistically at par with 160 kg P ha−1 (82.9%), whereas lowest shelling (80.3%) was recorded with 40 kg P ha−1.


**Table 1.** Ear length, number of grain ear−1, thousand grains weight, grain yield, harvest index, and shelling percentage of maize hybrid as affected by phosphorus levels.

The increase in the yield components (length, number of grains ear−1, and thousand grains weight), grain yield, harvest index, and shelling percentage with the application of higher P rates (120 and 160 kg P ha−1) over lower rates of P (40 and 80 kg P ha−1) as shown in **Table 1** could be due to the higher requirement of P by maize hybrid. These results are in accordance with those of [32, 33] that number of cobs increased with the increase in the level of organic and inorganic fertilizers. According to [34], ear lengths in maize increased while increasing P level, while [35] reported that the application of P significantly increased the number of grains ear−1 in maize. These results are in agreement with those of [6, 35] that increase in P level increased maize grain yield. According to [41], grain yield in maize increased to maximum level with the application of 90 kg P ha−1. The increase in harvest index with higher P levels might be due to the increase in yield and yield components of maize with higher P rates [6]. The increase shelling percentage with increase in the P level probably may be due to the increase in ear length, number of rows, and number of grains per ear as well as heaviest grain weight [4]. The results published from the same study [11] indicated that maize phenology (tasseling, silking, and physiological maturity) was delayed with lower P levels (40 and 80 kg ha−1) levels. Phenological development enhanced (early development) was observed with the application of higher P levels (120 and 160 kg ha−1). The reason for early phenology with the application of higher P levels might be due to better root development and thus facilitated the plants obtained more P and other nutrient from poultry manure for rapid plant growth and development. These findings are in line with those of [31] who reported that early phenological development with higher P levels. Growth parameters (plant height, mean single leaf area, and leaf area index) were significantly improved with the application of two higher P levels [11]. The biomass yield was significantly increased with the application of 120 or kg P ha−1 and poultry manure. Reduction in biomass yield was observed with the application of 40 kg P ha −1 and cattle manure. The increase in biomass yield reflects the better growth and development of the plants due to balanced and more availability of nutrients, which was associated with increased root growth due to which the plants explore more soil nutrients and moisture throughout the growing period. The increase in biomass yield with integrated use of 120 and 160 kg P ha−1 + poultry manure in our experiment was attributed to the improvement in growth parameters that increased yield and yield components in maize. These results are in line agreement with [45] who stated that the application of P fertilizer significantly increased the biomass and grain yield of maize.

The results from another research on wheat crop [46] revealed that the increase in P level accumulated more total dry matter (DM) and portioned more DM into leaf, stem, and spike at both anthesis and physiological maturity. A large amount of DM was accumulated in response to the application of the highest rate of (90 kg P ha−1). The increase in total DM accumulation with increase in P probably may be due P being the components of ATP might have contributed to a higher photosynthetic rate, abundant vegetative growth and assimilates formation and partitioning [47]. The results are also in accordance with those of [48] who reported increase in DM partitioning and accumulation while increasing rate of P. The increase in number of spikes m−2 and grains per spike with increase in P level probably may be the major cause for increasing total DM accumulation and greater amount of partitioning into various plant parts especially the reproductive parts which increased grain yield. Memon et al. [49] and Rahim et al. [50] reported that grains per spike in wheat increased with increase in P level. Recently [10], we found that phosphorus levels had significantly (P ≤ 0.05) affected number of grains ear−1 and grain srow−1, 1000 grains weight, grain yield, harvest index, and shelling percentage in maize. Phosphorus applied at the two higher rates (75 and 100 kg P ha −1) had increased number of grains ear−1 and grains row−1, 1000 grains weight, grain yield, harvest index, and shelling percentage in local variety "Azam" [10]. Decrease in P level not only decreased yield and yield components of maize "Azam" but also declined the income of maize growers under semiarid climates [4, 10].

#### **3.2. Effect of AM**

**Phosphorus (kg ha-1) Ear length (cm) Grains**

142 Organic Fertilizers - From Basic Concepts to Applied Outcomes

of maize hybrid as affected by phosphorus levels.

**ear-1**

**Thousand grains weight (g)**

**Table 1.** Ear length, number of grain ear−1, thousand grains weight, grain yield, harvest index, and shelling percentage

The increase in the yield components (length, number of grains ear−1, and thousand grains weight), grain yield, harvest index, and shelling percentage with the application of higher P rates (120 and 160 kg P ha−1) over lower rates of P (40 and 80 kg P ha−1) as shown in **Table 1** could be due to the higher requirement of P by maize hybrid. These results are in accordance with those of [32, 33] that number of cobs increased with the increase in the level of organic and inorganic fertilizers. According to [34], ear lengths in maize increased while increasing P level, while [35] reported that the application of P significantly increased the number of grains ear−1 in maize. These results are in agreement with those of [6, 35] that increase in P level increased maize grain yield. According to [41], grain yield in maize increased to maximum level with the application of 90 kg P ha−1. The increase in harvest index with higher P levels might be due to the increase in yield and yield components of maize with higher P rates [6]. The increase shelling percentage with increase in the P level probably may be due to the increase in ear length, number of rows, and number of grains per ear as well as heaviest grain weight [4]. The results published from the same study [11] indicated that maize phenology (tasseling, silking, and physiological maturity) was delayed with lower P levels (40 and 80 kg ha−1) levels. Phenological development enhanced (early development) was observed with the application of higher P levels (120 and 160 kg ha−1). The reason for early phenology with the application of higher P levels might be due to better root development and thus facilitated the plants obtained more P and other nutrient from poultry manure for rapid plant growth and development. These findings are in line with those of [31] who reported that early phenological development with higher P levels. Growth parameters (plant height, mean single leaf area, and leaf area index) were significantly improved with the application of two higher P levels [11]. The biomass yield was significantly increased with the application of 120 or kg P ha−1 and poultry manure. Reduction in biomass yield was observed with the application of 40 kg P ha −1 and cattle manure. The increase in biomass yield reflects the better growth and development of the plants due to balanced and more availability of nutrients, which was associated with increased root growth due to which the plants explore more soil nutrients and moisture throughout the growing period. The increase in biomass yield with integrated use of 120 and 160 kg P ha−1 + poultry manure in our experiment was attributed to the improvement in growth parameters that increased yield and yield components in maize. These results are in line

 20 d 385 d 331.2 c 4284 c 38.49 c 80.3 c 21 c 400 c 338.9 b 4754 b 40.28 b 81.5 b 25 a 417 a 346.5 a 5164 a 40.55 ab 83.6 a 23 b 406 b 347.8 a 5245 a 42.13 a 82.9 a **LSD0.05 0.94 4.43 1.77 159.01 1.63 0.99** Means followed by different letters within each category are significantly different using LSD test (P ≤ 0.05).

**Grain yield (kg ha-1)**

**Harvest index (%)** **Shelling percentage (%)**

> AM significantly affected ear length, number of grains ear−1, thousand grains weight, grain yield, and harvest index (**Table 2**). Plots applied with poultry manure resulted in higher ear length (24 cm), followed by sheep manure (22 cm), which is statistical at par with cattle manure (21 cm). In case of AM, application poultry manure produced higher number of grains ear−1 (414) lower (391) was observed under cattle manure being at par with the sheep manure (401). In the three AM used, application of poultry manure produced heavier thousand grains weight (348.2 g), followed by sheep manure (341.0 g), while cattle manure resulted in lower thousand grains weight (334 g). The highest grain yield (5216 kg ha−1) was recorded with application of poultry manure, followed by sheep manure (4786 kg ha−1), whereas the lowest grain yield (4583 kg ha−1) was obtained with cattle manure. Maximum harvest index (42.09%) was observed with poultry manure, while minimum harvest index (39.14%) was recorded with cattle manure being at par with sheep manure (39.85%). In case of AM, poultry manure application increased shelling percentage (84%); however, lower shelling percentage (81.1%) was calculated with cattle manure being at par with the sheep manure (82.2%). The increase in the yield components (length, number of grains ear−1, and thousand grains weight) with the application of poultry manure (**Table 2**) over cattle and sheep manures probably may be due to the higher availability crop nutrients specially P and other macronutrients and micronutrients. These results are in accordance with those of [51, 52] that number of cobs increased with the increase in the level

of organic and inorganic fertilizers. According to many studies, application manure increased tassel length [53], 1000 grains weight [54], and number of grains ear−1 in maize [55]. In our recent study, we found that the residual effect of poultry manure was also found better on the yield components of wheat under rice–wheat cropping system as compared with sheep manure and cattle manure [32]. Many researchers [56, 57] reported that poultry manure significantly increased the grain yield in maize. According to [53], increase in the poultry manure doses had significantly increased harvest index in maize, while [58] reported that poultry manure increased the shelling percentage in maize. The results published from the same study [11] indicated that phenological development delayed with the application of poultry manure as compared with other two manures (sheep and cattle manures) reported delayed in phenology with the application of poultry manure. The growth parameters were also significantly improved with application of poultry manure and there by increased grain yield and yield components in maize over sheep and cattle manures [11] suggested that poultry manure enhanced the LAI in maize. The improvement in growth and yield with the application of poultry manure probably may be due to the enhanced lead area, total chlorophyll content, carbon content, water holding capacity, and decrease bulk density of soil [59]. Earlier the results published from the same study [11] indicated that maize biomass yield was significantly increased with the application of poultry manure as compared with cattle and sheep manure (poultry manure > sheep manure > cattle manure). The increase in biomass yield was attributed to the better growth and development of the plants due to balanced and more availability of nutrients which was associated with increased root growth due to which the plants explore more soil nutrients and moisture throughout the growing period [11, 60]. The increase in biomass yield showed positive relationship with grain yield.


Means followed by different letters within each category are significantly different using LSD test (P ≤ 0.05).

**Table 2.** Ear length, number of grain ear−1, thousand grains weight, grain yield, harvest index, and shelling percentage of maize hybrid as affected by animal manures.

#### **3.3. Effect of PSB (biofertilizer)**

The PSB had no nonsignificant effect on ear length and harvest index, while number of grains ear−1, thousand grains weigh, grain yield, and shelling percentage was significantly affected by PSB (**Table 3**). Higher number of grains ear−1 (409) was obtained in the plots applied with PSB than without PSB (395). Plots with PSB had produced heavier thousand grains weight (342.0 g) than plots without PSB. The +PSB vs. −PSB comparison indicated that the plots with of organic and inorganic fertilizers. According to many studies, application manure increased tassel length [53], 1000 grains weight [54], and number of grains ear−1 in maize [55]. In our recent study, we found that the residual effect of poultry manure was also found better on the yield components of wheat under rice–wheat cropping system as compared with sheep manure and cattle manure [32]. Many researchers [56, 57] reported that poultry manure significantly increased the grain yield in maize. According to [53], increase in the poultry manure doses had significantly increased harvest index in maize, while [58] reported that poultry manure increased the shelling percentage in maize. The results published from the same study [11] indicated that phenological development delayed with the application of poultry manure as compared with other two manures (sheep and cattle manures) reported delayed in phenology with the application of poultry manure. The growth parameters were also significantly improved with application of poultry manure and there by increased grain yield and yield components in maize over sheep and cattle manures [11] suggested that poultry manure enhanced the LAI in maize. The improvement in growth and yield with the application of poultry manure probably may be due to the enhanced lead area, total chlorophyll content, carbon content, water holding capacity, and decrease bulk density of soil [59]. Earlier the results published from the same study [11] indicated that maize biomass yield was significantly increased with the application of poultry manure as compared with cattle and sheep manure (poultry manure > sheep manure > cattle manure). The increase in biomass yield was attributed to the better growth and development of the plants due to balanced and more availability of nutrients which was associated with increased root growth due to which the plants explore more soil nutrients and moisture throughout the growing period [11, 60]. The increase in

biomass yield showed positive relationship with grain yield.

144 Organic Fertilizers - From Basic Concepts to Applied Outcomes

**Ear length (cm) Grains ear-1 Thousand**

**grains weight (g)**

**Table 2.** Ear length, number of grain ear−1, thousand grains weight, grain yield, harvest index, and shelling percentage

The PSB had no nonsignificant effect on ear length and harvest index, while number of grains ear−1, thousand grains weigh, grain yield, and shelling percentage was significantly affected by PSB (**Table 3**). Higher number of grains ear−1 (409) was obtained in the plots applied with PSB than without PSB (395). Plots with PSB had produced heavier thousand grains weight (342.0 g) than plots without PSB. The +PSB vs. −PSB comparison indicated that the plots with

Sheep manure 22 b 401 b 341.0 b 4786 b 39.85 b 81.2 b Poultry manure 24 a 414 a 348.2 a 5216 a 42.09 a 84.0 a Cattle manure 21 b 391 b 334.0 c 4583 c 39.14 c 81.1 b **LSD0.05 1.38 10.93 2.16 194.93 2.12 1.14** Means followed by different letters within each category are significantly different using LSD test (P ≤ 0.05).

**Grain yield (kg ha-1)**

**Harvest index (%)** **Shelling percentage (%)**

**Animal manure (5 t ha-1)**

of maize hybrid as affected by animal manures.

**3.3. Effect of PSB (biofertilizer)**

PSB (+PSB) produced higher grain yield (4993 kg ha−1) than plots without PSB (4730 kg ha−1). Higher shelling percentage (82.9%) was obtained with PSB and lower (81.2%) at without PSB. The increase in the yield components (number of grains ear−1 and thousand grains weight), grain yield, and shelling percentage of maize seed treatment with PSB over not treated maize seeds (**Table 3**) probably may be due to the higher availability of crop nutrients and increase in beneficial soil microbes. According to [10, 45, 61, 62], PSB application resulted in higher yield components and grain yield. The results published from the same study [11], however, indi‐ cated that plots with (+) and without (−) PSB had showed no significant differences in the phenological development of maize. However, other growth parameters were improved in maize crop grown under plots with (+) PSB than without (−) PSB. Application of phosphatesolubilizing microorganism improving soil fertility by releasing bound P therefore improves crop growth and increases crop productivity [29]. In contrast to our results, [45, 61] reported that the inoculation of maize with PSB under greenhouse and field conditions increased bio‐ mass yield of maize. According to [62], biofertilizer (*Pseudomonas*) significantly increased the biomass yield of maize over control. Our recent results on wheat [46] also revealed that the application of beneficial microorganisms (BMO) at the two higher levels (20 and 30 L ha−1) accumulated more total DM and partitioned more DM into leaf, stem, and spike at both an‐ thesis and PM. Because BMO applications increase the availability of plant nutrients, especially P availability to the plants that resulted in better plant growth and higher production [63–65]. Dobblaere et al. [66] assessed the inoculation effect of BMO on growth of spring wheat and observed that inoculated wheat plants had better growth, more number of grains spike−1, and grain yield. Significant differences were found in number grains ear−1 and grains row−1, 1000 grains weight, grain yield, and shelling percentage between the plots treated with PSB (+) and without PSB (−) [10]. Plots applied with PSB (+) had produced more numbers of grains ear−1 and grains row−1, heavy 1000 grains weight, higher grain yield, and shelling percentage than plots without PSB (−). However, no significant differences were observed for harvest index between the plots with PSB (+) and without PSB (−).


Means followed by different letters within each category are significantly different using LSD test (P ≤ 0.05). ns, nonsignificant at 5% level of probability. \*Significant at 5% level of probability.

**Table 3.** Ear length, number of grain ear−1, thousand grains weight, grain yield, harvest index, and shelling percentage of maize hybrid as affected by with (+) and without (−) PSB inoculation.


\*Significant at 5% level of probability.

**Table 4.** Ear length, number of grain ear−1, thousand grains weight, grain yield, harvest index, and shelling percentage of maize hybrid as affected by interactions.

#### **3.4. Interactive effect**

All interactions (AM × PSB, AM × P, PSB × P, and AM × PSB × P) had no significant effect on ear length, grain yield, and harvest index of maize **(Table 4)**. Number of grains ear−1 was significantly affected by AM × P, PSB × P, and AM × PSB × P interactions **(Table 4)**. Interaction between AM × P indicated that the increase in number of grains ear−1 with the combination of poultry manure + 120 kg P ha−1, and the plots that received cattle manure along with 40 kg P ha−1 produced minimum number of grains ear−1 (**Figure 1**). Significant increase in number of grains ear−1 was observed with PSB + 120 kg P ha−1, and plots that received 40 kg P ha−1 without PSB application resulted in the lowest number of grains ear−1 (**Figure 2**). The three-way interaction among AM × PSB × P indicated that the highest number of grains ear−1 was recorded in plots under poultry manure + 160 kg P ha−1 + PSB. Plots having cattle manure + 40 kg P ha −1 without PSB produced the lowest number of grains ear−1 (**Figure 3**). The results published from the same study [11] indicated that higher mean single leaf area and maximum leaf area index (4.28) were recorded with the combined application of higher P levels, viz 120 or 160 kg P ha−1 + poultry manure along with PSB inoculation. The lower mean single leaf area and minimum leaf area index (3.65) were recorded with the combined application of sheep manure + 40 kg P ha−1 without seed inoculation with PSB (−) and therefore resulted in significant AM × PSB × P interactions [11].

**Figure 1.** Response of number of grains ear−1 in hybrid maize to animal manures and phosphorus interaction (AM × P).

Integrated Use of Phosphorus, Animal Manures and Biofertilizers Improve Maize Productivity under Semiarid Condition http://dx.doi.org/10.5772/62388 147

**Interactions Ear length (cm) Grains**

146 Organic Fertilizers - From Basic Concepts to Applied Outcomes

ns, nonsignificant at 5% level of probability. \*Significant at 5% level of probability.

of maize hybrid as affected by interactions.

**3.4. Interactive effect**

× PSB × P interactions [11].

**ear−1**

**Thousand grains weight (g)**

AM × PSB ns ns (**Figure 4**)\* ns ns (**Figure 7**)\* AM × P ns (**Figure 1**)\* (**Figure 5**)\* ns ns (**Figure 8**)\*

**Table 4.** Ear length, number of grain ear−1, thousand grains weight, grain yield, harvest index, and shelling percentage

All interactions (AM × PSB, AM × P, PSB × P, and AM × PSB × P) had no significant effect on ear length, grain yield, and harvest index of maize **(Table 4)**. Number of grains ear−1 was significantly affected by AM × P, PSB × P, and AM × PSB × P interactions **(Table 4)**. Interaction between AM × P indicated that the increase in number of grains ear−1 with the combination of poultry manure + 120 kg P ha−1, and the plots that received cattle manure along with 40 kg P ha−1 produced minimum number of grains ear−1 (**Figure 1**). Significant increase in number of grains ear−1 was observed with PSB + 120 kg P ha−1, and plots that received 40 kg P ha−1 without PSB application resulted in the lowest number of grains ear−1 (**Figure 2**). The three-way interaction among AM × PSB × P indicated that the highest number of grains ear−1 was recorded in plots under poultry manure + 160 kg P ha−1 + PSB. Plots having cattle manure + 40 kg P ha −1 without PSB produced the lowest number of grains ear−1 (**Figure 3**). The results published from the same study [11] indicated that higher mean single leaf area and maximum leaf area index (4.28) were recorded with the combined application of higher P levels, viz 120 or 160 kg P ha−1 + poultry manure along with PSB inoculation. The lower mean single leaf area and minimum leaf area index (3.65) were recorded with the combined application of sheep manure + 40 kg P ha−1 without seed inoculation with PSB (−) and therefore resulted in significant AM

**Figure 1.** Response of number of grains ear−1 in hybrid maize to animal manures and phosphorus interaction (AM × P).

PSB × P ns (**Figure 2**)\* ns ns ns ns AM × PSB × P ns (**Figure 3**)\* (**Figure 6**)\* ns ns ns

**Grain yield (kg ha−1)** **Harvest index (%)** **Shelling percentage (%)**

**Figure 2.** Response of number of grains ear−1 in hybrid maize to phosphate-solubilizing bacteria and phosphorus inter‐ action (PSB × P).

**Figure 3.** Response of number of grains ear−1 in hybrid maize to animal manures, phosphate-solubilizing bacteria and phosphorus interaction (AM × PSB × P).

Thousand grains weight was significantly affected by AM × PSB, AM × P, and AM × PSB × P interactions (**Table 4**). Interaction between AM × PSB indicated that heavier thousand grains weight was recorded in plots applied with poultry manure under PSB, and plots that received cattle manure with no PSB applied reduced thousand grains weight (**Figure 4**). The results from the same study [11] indicated that delayed physiological maturity (104 days) was recorded with the application of poultry manure along with PSB inoculation, while early days to physiological maturity (101 days) was observed with the application of cattle manure along with PSB inoculation. The P × PSB interaction indicated that the highest thousand grains weight was observed in plots under poultry manure along with 160 kg P ha−1, and plots received cattle manure with 40 kg P ha−1 resulted in lowest thousand grains weight (**Figure 5**). Interaction among AM × PSB × P showed that the highest thousand grains weight was recorded in plots under poultry manure + 160 kg P ha−1 + PSB (**Figure 6**). Plots having cattle manure + 40 kg P ha−1 without PSB application reduced thousand grains weight to minimum (**Figure 6**).

**Figure 4.** Response of 1000 grains weight (g) in hybrid maize to animal manures and phosphate-solubilizing bacteria interaction (AM × PSB).

**Figure 5.** Response of 1000 grains weight (g) in hybrid maize to animal manures and phosphorus interaction (AM × P).

**Figure 6.** Response of 1000 grains weight (g) in hybrid maize to animal manures, phosphate-solubilizing bacteria and phosphorus interaction (AM × PSB × P).

Amanullah and Khan [10] reported that the interaction between P levels and PSB (P × PSB) had significant effect on number of grains per row and grain yield. They found that the two higher P levels (75 and 100 kg P ha−1) had produced significantly more number of grains per row in maize grown under both with (+) and without PSB (−) treated plots [10]. The two higher P levels (75 and 100 kg P ha−1) had produced significantly higher grain yield grain yield than the two lower levels of P (25 and 50 Kg P ha−1) in the plots treated with (+) and plots, where PSB was not applied [10]. Many researchers [26, 67, 68] also suggested that the seed inoculation with PSB along with the application of soluble phosphatic fertilizer decreases P fixation on calcareous, thereby increasing P use efficiency and grain yield.

Shelling percentage was also significantly affected by the interaction between AM × PSB and AM × P **(Table 4)**. Interaction between AM × PSB indicated that the application of poultry manure with PSB increased while the application of sheep manure without PSB decreased shelling percentage in maize (**Figure 7**). Interaction between AM × P indicated that the highest shelling percentage was calculated with poultry manure + 120 kg P ha−1, and the lowest shelling percentage was calculated for the combination of sheep manure + 40 kg P ha−1 (**Figure 8**). Increase in yield and yield components of maize was reported earlier by Cheema et al. [69], Zafar et al. [70], Khan et al. [71], and Iqbal et al. [39] with integrated application of organic and inorganic fertilizers under semiarid climates. Amanullah and Stewart [72] found that wheat and rye responded differently in growth under different soil types. Both crops had better performance in terms of higher leaf area per plant, leaf area expansion rate, specific leaf area, leaf area ratio, plant height, stem elongation rate, root length, number of roots per plant, number of tillers per plant, absolute growth rate, and crop growth rate under organic soils as compared with inorganic soils at different growth stages [72]. Recently Amanullah and Khan [10] reported that integrated use of inorganic P fertilizer at higher rates + organic matter (in the form of compost) along with the seed inoculation with PSB significantly increases grain yield and yield components of maize under the semiarid climate of Peshawar Valley. Organic agriculture is important for the improvement of the environmental conditions and human health [73, 74].

**Figure 4.** Response of 1000 grains weight (g) in hybrid maize to animal manures and phosphate-solubilizing bacteria

**Figure 5.** Response of 1000 grains weight (g) in hybrid maize to animal manures and phosphorus interaction (AM × P).

**Figure 6.** Response of 1000 grains weight (g) in hybrid maize to animal manures, phosphate-solubilizing bacteria and

interaction (AM × PSB).

148 Organic Fertilizers - From Basic Concepts to Applied Outcomes

phosphorus interaction (AM × PSB × P).

**Figure 7.** Response of shelling (%) in hybrid maize to animal manures and phosphate-solubilizing bacteria interaction (AM × PSB).

**Figure 8.** Response of shelling (%) in hybrid maize to animal manures and phosphorus interaction (AM × P).

#### **4. Conclusions**

Phosphorus unavailability and lack of organic matter in the soils in semiarid condition are the major reasons for low crop productivity. The results obtained from this field research work indicated that among the three AM used in the experiment (cattle manure, sheep manure, and poultry manure), poultry manure was found more beneficial in terms of better yield compo‐ nents (longer ear lengths, higher number of grains ear−1, heavier grains) that resulted in higher grain yield, harvest index, and shelling. Among the four P levels (40, 80, 120, and 160 kg P2O5 ha−1), application of P at the rate of 120 kg ha−1 had increased the ear length, number of grains ear−1, and shelling percentage. Application of P at the highest rate of 160 kg P ha−1 increased grains weight, grain yield and harvest index. The plots treated with PSB (seed inoculation) had produced significantly higher yield and yield components of maize as compared with noninoculated seeds. We concluded from these results that the integrated use of phosphorus (160 kg ha−1) + poultry manure along with the seed inoculation with PSB could improve maize productivity under semiarid condition. Organic agriculture is also important for the improve‐ ment of the environmental conditions and human health.

### **Author details**

Dr. Amanullah\* and Shah Khalid

\*Address all correspondence to: amanullah@aup.edu.pk

Department of Agronomy, Faculty of Crop Production Sciences, The University of Agriculture, Pakistan
