**9. Agronomic management practice and nutritional status of soybean**

#### **9.1 Fertilization**

In general, mainly fertilization of soybean with nitrogen, phosphorus and potassium are common agronomic practice. Additional using the other nutrients are more exception than rule. In some cases application of the higher P and K rates are needed for achieving of satisfied yields of soybean.

correlation among the variables shoot-DM, total-DM and shoot P-concentration and Pefficiency index (EI). Cultivars were classified in efficient-responsive (ER)¾ *IAC-1, IAC-2, IAC-4, IAC-5, IAC-6, IAC-9*, *Sta. Rosa* and *UFV-1*; efficient-non-responsive (ENR) ¾ *IAC-7*, *IAC-11, IAC-15, S. Carlos* and *Cristalina*; inefficient-responsive (IR) ¾ *IAC-8, IAC-10, IAC-14, Bossier* and *Foscarin*; and inefficient-non-responsive (INR) ¾ *IAC-12, IAC-13, IAC-16, IAC-17, IAC-18, IAC-19, IAC-20, IAC-22, Paraná*, *IAS-5* and *BR-4.* The efficient-responsive soybean cultivars showed the highest values for shoot and total DM and EI, and the lowest shoot P-

Properties of uninoculated ( **-** = control) and inoculated (**+**) soybeans

**- + - + - + - +** 

Nitrogen

(% N) t/ha

Soybean Nodule Above-ground part of plant Grain yield

OS-1-00 0 44.6 4.29 6.19 1.84 2.65 3.54 4.05 OS-2-00 0 37.8 3.41 4.91 1.69 2.44 3.39 3.85 OS-1-0 0 38.2 3.34 4.80 1.71 2.46 3.53 4.02 OS-2-0 0 35.8 3.21 4.62 1.67 2.40 3.36 3.81 OS-3-0 0 49.2 4.24 6.11 1.84 2.65 3.42 4.00 OS-1-I 0 31.9 2.64 3.80 1.46 2.11 3.57 4.03 OS-2-I 0 36.3 3.24 4.67 1.65 2.38 3.83 4.33 OS-3-I 0 40.2 4.17 6.00 1.82 2.62 3.71 4.23

Table 15. Mean values of nitrogen fixation indicators and grain yield of 8 soybean cultivars

Ojo et al. (2010) tested 55 soybean genotypes under acid soil conditions in area of Umudike, Nigeria for two growing seasons. Highly significant differences in genotypic effects were observed for all the traits (days to 50% flowering, plant height at maturity, number of pods/plant, 100-seed weight and grain yield). Eight acid tolerant varieties were found (*Conqvista, TGX 1896-3F, TGX 1897-17F, TGX 1866-7F, TGX 1805-31F, Milena, Doko* and *TGX 1844-18E*) with a higher grain yield of >1.80tons/ha compared to <1.45tons/ha in the previously recommended varieties (*TGX 1485- 1D* and *TGX 1440-1E*). The result also showed the potential of the EMBRAPA genotypes in upgrading the TGX varieties for higher productivity. The eight identified acid tolerant varieties could therefore be explored in the development of improved high yielding soybean genotypes for production on acid soils of

**9. Agronomic management practice and nutritional status of soybean** 

In general, mainly fertilization of soybean with nitrogen, phosphorus and potassium are common agronomic practice. Additional using the other nutrients are more exception than rule. In some cases application of the higher P and K rates are needed for achieving of

LSD 5% 4.0 1.13 0.22 0.31 LSD 1% 5.3 2.02 0.41 0.36

cultivar number/plant Dry matter weight

(2004-2007; Osijek, Croatia) (Sudaric et al., 2008)

(g)

concentrations.

Nigeria.

**9.1 Fertilization** 

satisfied yields of soybean.

Phosphorus and potassium are limiting factor of field crops yield on some hydromorphic soils in Croatia (Kovacevic, 1993; Kovacevic et al., 2007; 2011; Rastija et al., 2006). By application of the ameliorative rates of NPK fertilizer up to 3748 kg/ha level soybean yields were increased up to 32 %. Protein contents in soybean grain were independent on the fertilization, while oil contents were increased up to 0.66% compared to the control (Rastija, et al., 2006). In the second experiment, P and K applied separately up to 1500 kg/ha either P2O5 or K2O and in their combination (1000 + 1000 kg/ha). Yields of soybean were increased up to 21% (influences of P), 17% (influences of K) and 30% (PK influences). However, protein and oil contents in grain were independent on fertilization (Kovacevic et al., 2007). Soybean is generally responsive to fertilization with inadequate nutrient supplies. For example, grain yields of soybeans were increased by 40% and 34% as affected by the K and P fertilization, respectively (Table 16). According to status of the uppermost full-developed trifoliate leaf (Jones, 1967, cit. Bergmann and Neubert, 1976; Bergman, 1992) the adequate P, and high Ca and Mg status as well as low K status was found in the soybean leaves when ordinary fertilization was applied (Table 16). However, nutritional status of soybean was considerably improved when affected by the ameliorative fertilization. Calcium uptake by soybean leaves was high and it was practically independent on the fertilization. Also, the K fertilization influenced the Mg status in soybean leaves: it was decreased in relative amount by about 30 % compared to ordinary fertilization. More favorable relationship between K and Mg was associated with K fertilization: 1.13 and 3.20 for ordinary fertilization and the highest rate of added K, respectively (Table 16).

Rastija et al. (2006) applied four rate of ameliorative PK-fertilization on acid soil. As affected by the fertilization grain yields of soybean were increased up to 32%. However, yield differences among three ameliorative treatments were non-significant. Protein contents in soybean grain were independent on the fertilization, while oil contents were increased up to 0.66% compared to the control (Table 17).


Fertilization (March 22, 1990) by P and K rates on equal (kg/ha: 90 N + 137 P2O5+ 132 K2O) NPK fertilization and soybean propreties (the growing season 1990: the uppermost full-developed trifoliate leaf before anthesis)

Table 16. Response of soybean to ameliorative P and K fertilization (Kovacevic, 1993)

Kovacevic et al. (2007) tested response of soybean to ameliorative P and K fertilization alone or in their combination. As affected by applied fertilization soybean yields were increased up to 21% (influences of P), 17% (influences of K) and 30% (PK influences). However, protein and oil contents in grain were indenpendent on fertilization (Table 18).


Table 17. Residual impact of PK-fertilization on soybean properties (Rastija et al., 2006)

Kovacevic et al. (2011) reported residual impacts of increasing rates of PK-fertilization up to 1000 kg P2O5/ha and 672 K2O/ha in spring 2004 and liming by granulated fertdolomite (24.0 % CaO + 16.0 % MgO + 3.0 % N + 2.5 % P2O5 + 3.0 % K2O) in autumn 2007 on soybean status in the growing season 2010. As affected by liming yields of soybean were increased for 18 % (means 3279 and 3854 kg/ha, for unlimed and limed plots, respectively). Also, grain quality parameters were improved by liming (thousand grain weight were 151.8 and 168.3 g; protein contents were 35.24 and 39.06 %, respectively), while oil contents were decreased (23.84 and 22.62 %, respectively). However, impact of P and K fertilization was considerably lower in comparison with liming (Table 19).


Table 18. Residual influences of NPK-fertilization on soybean properties (Kovacevic et al., 2007)

41.92 40.89 41.42 40.64 41.94 20.33 20.80 20.62 20.99 20.73

\* the uppermost full-developed threefoliate leaf before

0.530 0.537 0.571 0.487 0.501 2.67 2.71 2.85 2.73 2.69

Fertilization (April 23, 2004) Soybean properties (the 2005 growing season) kg/ha (t/ha) Percent in dry matter Treatment P2O5 K2O Grain Grain Leaves\*

> 3.88 4.87 4.73 4.98 5.14

anthesis

Control PK-1 PK-2 PK-3 PK-4

b c d

e f g

82 K2O

2007)

P-1 P-2 P-3

K-1 K-2 K-3

lower in comparison with liming (Table 19).

82 82 82

582 1082 1582

> LSD 5% LSD 1%

625 1125 1625

125 125 125

\* for next year: 80 N + 125 P2O5 +

yield Protein Oil P K

LSD 5% 0.72 n.s. n.s. n.s. n.s.

Table 17. Residual impact of PK-fertilization on soybean properties (Rastija et al., 2006)

Fertilization (April 23, 2004)\* Soybean properties (the 2005 growing season) kg/ha kg/ha Percent in dry matter Treatment P2O5 K2O Grain Grain Leaves\* yield Protein Oil P K a Control 125 82 3600 41.27 20.74 0.537 2.81

> 3580 3460 4360

> 4010 4200 4080

370

anthesis

Table 18. Residual influences of NPK-fertilization on soybean properties (Kovacevic et al.,

h P2K2 1125 1082 4670 40.28 21.14 0.593 3.05

40.76 41.57 41.74

41.13 40.21 40.59

<sup>510</sup>n.s. n.s.

20.83 20.64 20.52

21.20 21.10 21.10

\* the uppermost full-developed trifoliate leaf before

0.513 0.593 0.603

0.520 0.547 0.573

0.055 n.s.

2.86 3.15 2.88

2.87 2.95 3.29

0.30 n.s.

Kovacevic et al. (2011) reported residual impacts of increasing rates of PK-fertilization up to 1000 kg P2O5/ha and 672 K2O/ha in spring 2004 and liming by granulated fertdolomite (24.0 % CaO + 16.0 % MgO + 3.0 % N + 2.5 % P2O5 + 3.0 % K2O) in autumn 2007 on soybean status in the growing season 2010. As affected by liming yields of soybean were increased for 18 % (means 3279 and 3854 kg/ha, for unlimed and limed plots, respectively). Also, grain quality parameters were improved by liming (thousand grain weight were 151.8 and 168.3 g; protein contents were 35.24 and 39.06 %, respectively), while oil contents were decreased (23.84 and 22.62 %, respectively). However, impact of P and K fertilization was considerably


Table 19. Residual effects of PK-fertilization (April 2004) and liming (Oct. 2007) on soybean (Kovacevic et al., 2011)



P treatments received a blanket application of 108 kg K/ha; K treatments received a blanket application of 60 kg P/ha;

Sufficiency ranges at the uppermost threefoliate leaves R2 stage: 0.26-0.50 % P and 1.71-2.50 % K

Table 20. Response of soybean to P and K fertilization (Casanova, 2000)

Casanova (2000) reported that the primary nutritional limitation for successful soybean production under savanna soils in Venezuela (Guarico state) are soil acidity and deficiencies of P, K, N and Ca. Other nutrients as Mg, S and Zn become limiting when the soil is cultivated for several years. Application of triple superphosphate up to 70 kg P/ha and potassium chloride up to 135 kg K/ha on fixed rate of 108 kg K/ha for P plots and 60 kg P/ha for K plots resulted by considerable yield increases. The treatment combination of 60 kg P/ha and 108 kg K/ha produced the best grain yield of 3.16 t/ha (Table 20).

Mottaghian et al. (2008) applied in a silty loam soil in Mazandaran province, Iran, for soybean eight fertilization treatments as follows: 20 and 40 t/ha of organic fertilizers (municipal solid waste compost, vermicompost and sewage sludge) enriched with 50% of anorganic fertilizers need by the soil), only inorganic fertilizers (potassium sulphate and triplephosphate 75 kg/ha) and control (unfertilized). Mixture of 40 t/ha sewage sludge and inorganic fertilizers produced the highest yield and micronutrient (Mn, Cu, Zn and Fe) grain concentrations.

#### **9.2 Liming**

Acid soils occupy 3.95 billion ha (about 30 % of the world's ice-free land area (von Uexkull and Mutert, 1995). The poor production of crops grown in acid soils is due to combinations of toxicity (Al, Mn, Fe, H) and deficiencies (N, P, Ca, Mg, K, Fe, Zn). Soil acidity is certainly one of the most damaging soil conditions affecting the growth of most crops. Many factors are involved, but Al toxicity is of outermost significance because of damaging root growth and therefore reduces water and nutrient uptake.

Poor growth of soybean in acid soils as been attributed to a number of factors that include: low pH, high level of Al, Mn, and H, low levels of Ca, Mg, P, K, micronutrients like B, Zn etc. (Fageria, 1994), low population of beneficial micro-organisms like rhizobia, vesicular arbuscular (VAM) fungi and inhibition of root growth (Maddox and Soileux, 1991).

Management practices, such as acidificatying effects of acid-forming N fertilizers, removal of cations by harvested crops, increased leaching and leguminous crops (N2-fixation), have resulted in the lowering of natural soil pH (Baligar and Fageria, 1997).

Plant growth in mineral acid soils can be restricted by complex of factors. Malnutrition of plants on acid soils is mostly the results of limited soil nutrient availability, often strengthened by impaired uptake capability of the root. Based for over 5000 observations for soybeans worldwide, the optimum pH value for soybeans indicated by this approach lies between ph 5.7 and 6.0 (Sumner, 1997).

An optimum liming regime should achieve the reduction plant available Al and Mn concentrations to levels which allow optimal production of a particular crops, supplying adequate levels of plant available Ca and Mg for optimum root growth and crop performance, creating conditions for optimal performance of beneficial soil fauna and flora particularly int he rhizosfere, and in case of legumes, creating environment which promotes infection and nodulation of root with effective N-fixing rhizobia. (Keltjens, 1997).

For successful soybean production, large quantities of lime and phosphorus fertilizers may be required (Fageria *et al.*, 1995). Liming improves microbiological activities of acid soils, which in turn increases N fixation by legumes, and also promotes mineralization of organic materials. However, over liming may reduce crop yield by inducing P and micronutrient deficiencies (Fageria, 1984).

Unfortunately, over 50% of the world's potential arable land surface is composed of acid soils mostly distributed in developing countries (von Uexküll and Mutert, 1995; Kochian et al., 2005). This restricts the production of soybeans and other legumes due to their

Casanova (2000) reported that the primary nutritional limitation for successful soybean production under savanna soils in Venezuela (Guarico state) are soil acidity and deficiencies of P, K, N and Ca. Other nutrients as Mg, S and Zn become limiting when the soil is cultivated for several years. Application of triple superphosphate up to 70 kg P/ha and potassium chloride up to 135 kg K/ha on fixed rate of 108 kg K/ha for P plots and 60 kg P/ha for K plots resulted by considerable yield increases. The treatment combination of 60

Mottaghian et al. (2008) applied in a silty loam soil in Mazandaran province, Iran, for soybean eight fertilization treatments as follows: 20 and 40 t/ha of organic fertilizers (municipal solid waste compost, vermicompost and sewage sludge) enriched with 50% of anorganic fertilizers need by the soil), only inorganic fertilizers (potassium sulphate and triplephosphate 75 kg/ha) and control (unfertilized). Mixture of 40 t/ha sewage sludge and inorganic fertilizers produced

Acid soils occupy 3.95 billion ha (about 30 % of the world's ice-free land area (von Uexkull and Mutert, 1995). The poor production of crops grown in acid soils is due to combinations of toxicity (Al, Mn, Fe, H) and deficiencies (N, P, Ca, Mg, K, Fe, Zn). Soil acidity is certainly one of the most damaging soil conditions affecting the growth of most crops. Many factors are involved, but Al toxicity is of outermost significance because of damaging root growth

Poor growth of soybean in acid soils as been attributed to a number of factors that include: low pH, high level of Al, Mn, and H, low levels of Ca, Mg, P, K, micronutrients like B, Zn etc. (Fageria, 1994), low population of beneficial micro-organisms like rhizobia, vesicular

Management practices, such as acidificatying effects of acid-forming N fertilizers, removal of cations by harvested crops, increased leaching and leguminous crops (N2-fixation), have

Plant growth in mineral acid soils can be restricted by complex of factors. Malnutrition of plants on acid soils is mostly the results of limited soil nutrient availability, often strengthened by impaired uptake capability of the root. Based for over 5000 observations for soybeans worldwide, the optimum pH value for soybeans indicated by this approach lies

An optimum liming regime should achieve the reduction plant available Al and Mn concentrations to levels which allow optimal production of a particular crops, supplying adequate levels of plant available Ca and Mg for optimum root growth and crop performance, creating conditions for optimal performance of beneficial soil fauna and flora particularly int he rhizosfere, and in case of legumes, creating environment which promotes

For successful soybean production, large quantities of lime and phosphorus fertilizers may be required (Fageria *et al.*, 1995). Liming improves microbiological activities of acid soils, which in turn increases N fixation by legumes, and also promotes mineralization of organic materials. However, over liming may reduce crop yield by inducing P and micronutrient

Unfortunately, over 50% of the world's potential arable land surface is composed of acid soils mostly distributed in developing countries (von Uexküll and Mutert, 1995; Kochian et al., 2005). This restricts the production of soybeans and other legumes due to their

infection and nodulation of root with effective N-fixing rhizobia. (Keltjens, 1997).

arbuscular (VAM) fungi and inhibition of root growth (Maddox and Soileux, 1991).

resulted in the lowering of natural soil pH (Baligar and Fageria, 1997).

kg P/ha and 108 kg K/ha produced the best grain yield of 3.16 t/ha (Table 20).

the highest yield and micronutrient (Mn, Cu, Zn and Fe) grain concentrations.

and therefore reduces water and nutrient uptake.

between ph 5.7 and 6.0 (Sumner, 1997).

deficiencies (Fageria, 1984).

**9.2 Liming**

sensitivity to acid soil infertility. The growth of leguminous crops and development of symbiosis on acid soils are generally affected by deficiencies of Ca, K, P, Mg, S, Zn and Mo and/or toxicities of Al, Mn and Fe (Foy,1984; Clark et al., 1988).

Liming has been used to ameliorate the problem of aluminium toxicity and low pH in soils. Liming the top soil, however, remains a temporary solution due to subsoil acidity. Restriction in root growth due to subsoil acidity reduces plant nutrient acquisition and access to subsoil water which culminates in the reduction of crop yield (Ferrufino et al., 2000). Moreover, the cost of liming particularly in developing countries is prohibitive and does not justify such huge investment given the return on investment from grain yield of soybeans. The input cost of the recommended quantity of 0.5 to 1.00 tons/ha of liming material (Yusuf and Idowu, 2001), is about the expected total revenue from the current average yield of 0.7 tons/ha in the South-East and South-South regions of Nigeria. The identification of acid stress tolerant cultivars of soybeans, therefore, remains a viable alternative.

Opkara et al., (2007) conducted field experiments in Southeastern Nigeria, in the 2003 and 2004 growing seasons to assess the effect of liming on the performance of four high yielding soybean varieties (early maturing TGX 1485-1D, TGX 1799-8F, TGX 1805-8F and medium maturing TGX 1440-1E). Five lime rates of 0, 0.5, 1.0, 1.5 and 2.0 t/ha were applied to the main plots while the four soybean varieties were planted in the sub-plots. Liming significantly increased soil pH, number of nodules and number of pods per plant and grain yield, especially in 2004 but did not significantly influence plant height, shoot dry matter, days to 50% flowering and 100-seed weight. The 1.0 t/ha lime rate proved to be optimum and is thus recommended for high grain yield in soybean. Mean grain yield at 1.0 t/ha lime rates was higher than the yield in the control (no lime) by 66%. The medium maturing TGX 1440-1E gave, on the average, significantly higher number of leaves and number of pods per plant and grain yield than other varieties.

Kovacevic et al., (1987) tested response of maize, soybean and wheat on liming by hydrated lime to level 20 t/ha. The field experiment was conducted in triplicate for maize- soybeanwheat rotation. Depending on the year grain yield of soybean ranged between 2.59 and 4.03 t/ha. Liming with 10 t of lime increased soybean yield by 17 %. Increased lime rates did not affect grain yield. Low grain yield were obtained under dry and warm weather conditions in 1983 and cold and wet weather conditions in 1984. Liming with 20 tons of lime per hectare increased soil pH from 4.0 to 6.4 at end of the first year of testing (Table 21).


Table 21. Response of soybean to liming on Fericanci acid soil (Kovacevic et al., 1987)

Loncaric et al. (2007) applied liming with carbocalk up to 20 t/ha (spring 2003) and three degrees of fertilization (every year for 4-year period) on Donji Miholjac dystric luvisol. Soybean was grown on the experimental field in the fourth growing season (2006). Depending on the treatment, soybean yields were in range from 2.7 t/ha (unlimed and unfertilized plots) to 4.4 t/ha (treatment kg/ha: 140 N + 300 P2O5 + 300 K2O) and phosphorus removals (P2O5/ha) by soybean were 56 and 78, respectively.

#### **9.3 Soil tillage**

Different tillage techniques affect the root absorption of nutrients. Lavado et al. (2001) tested effects of conventional and zero tillage (CT and ZT) on nutritional status of soybean, wheat and maize with emphasis on heavy metals. The field experiments were conducted in area far from contaminated sources in Buenos Aires Province, Argentina. The effects of tillage were limited for nutrient concentrations, but significant for heavy metals. Soybean appeared to be more sensitive than cereals to the apparent effect of soil tillage. Grain composition of soybean was independent on soil tillage. Under CT conditions leaves and stem N as well as root Cu were significantly higher, while root -Zn, -Pb and -Ni were significantly lower in comparison with ZT (Table 22).


Table 22. Impacts of soil tillage on nutrient and heavy metal status of soybean (Lavado et al., 2001)

Jug et al (2006) reported about soil tillage impacts on nutritional status of soybean on chernozem soil for four growing seasons (stationary field experiment from 2002 to 2005). Three treatment of soil tillage were applied as follows: a) conventional tillage, b) reduced tillage (DH = diskharrowing instead of ploughing) and c) no-till (NT). In general, the characteristics of growing season (the factor "year") were more influencing factor of soybean nutritional status (aerial part in stage of full-developed pods) in comparison with the soil tillage. In this study, low influences of applied soil tillage treatments on nutritional status of soybean were found because significant differences on soybean composition were found only for four (Cu, Cr, Sr and Ba) from total 20 analysed elements. For example, conventional tillage resulted by the higher plant Cu (by 15% and 18% in comparison with DH and NT, respectively), and the lower plant Sr (by 12% and 16%, respectively) and Ba (by 26% and 23%, respectively), while under DH conditions by 22% lower plant Cr was found. Main nutrient status were independent on soil tillage (Table 23). For this reason, usual fertilization practice is recommended for possible application of soil tillage reduction under conditions of calcareous chernozem.

Loncaric et al. (2007) applied liming with carbocalk up to 20 t/ha (spring 2003) and three degrees of fertilization (every year for 4-year period) on Donji Miholjac dystric luvisol. Soybean was grown on the experimental field in the fourth growing season (2006). Depending on the treatment, soybean yields were in range from 2.7 t/ha (unlimed and unfertilized plots) to 4.4 t/ha (treatment kg/ha: 140 N + 300 P2O5 + 300 K2O) and

Different tillage techniques affect the root absorption of nutrients. Lavado et al. (2001) tested effects of conventional and zero tillage (CT and ZT) on nutritional status of soybean, wheat and maize with emphasis on heavy metals. The field experiments were conducted in area far from contaminated sources in Buenos Aires Province, Argentina. The effects of tillage were limited for nutrient concentrations, but significant for heavy metals. Soybean appeared to be more sensitive than cereals to the apparent effect of soil tillage. Grain composition of soybean was independent on soil tillage. Under CT conditions leaves and stem N as well as root Cu were significantly higher, while root -Zn, -Pb and -Ni were significantly lower in

Soil tillage treatments (ZT = zero tillage; CT = conventional tillage) and soybean nutritional status

 ZT CT ZT CT ZT CT ZT CT ZT CT ZT CT *Nitrogen Phosphorus Potassium Sulfur Copper Zinc*  G 33800a 46900a 4500a 1900a 19800a 18000a 2200a 2600a 17.10a 20.83b 44.85a 43.50a L+S 9500a 14400b 2100a 1500a 15000a 15000a 900a 800a 10.93a 13.45a 21.48a 18.70a R 7000a 8600a 2900a 900b 1300a 900a 800a 800a 18.70a 27.98b 64.73a 41.78a *Boron Molybdenum Lead Nickel Cadmium Chromium*  G 5.77a 6.15a 2.95a 1.71a 0.85a 0.80a 4.30a 4.26a <0.05a <0.05a 0.93a 1.20a L+S 4.03a 4.60a 1.49a 1.70a 0.69a 0.63a 1.55a 2.08a <0.05a <0.05a 1.74a 2.36a R 5.10a 6.00a 1.15a 1.36a 3.51a 2.41b 9.46a 6.77b <0.05a <0.05a 10.80a 11.93a \* Means with different letter in each row are significantly different between treatments at LSD 5 % Table 22. Impacts of soil tillage on nutrient and heavy metal status of soybean (Lavado et al.,

Jug et al (2006) reported about soil tillage impacts on nutritional status of soybean on chernozem soil for four growing seasons (stationary field experiment from 2002 to 2005). Three treatment of soil tillage were applied as follows: a) conventional tillage, b) reduced tillage (DH = diskharrowing instead of ploughing) and c) no-till (NT). In general, the characteristics of growing season (the factor "year") were more influencing factor of soybean nutritional status (aerial part in stage of full-developed pods) in comparison with the soil tillage. In this study, low influences of applied soil tillage treatments on nutritional status of soybean were found because significant differences on soybean composition were found only for four (Cu, Cr, Sr and Ba) from total 20 analysed elements. For example, conventional tillage resulted by the higher plant Cu (by 15% and 18% in comparison with DH and NT, respectively), and the lower plant Sr (by 12% and 16%, respectively) and Ba (by 26% and 23%, respectively), while under DH conditions by 22% lower plant Cr was found. Main nutrient status were independent on soil tillage (Table 23). For this reason, usual fertilization practice is recommended for possible application of soil tillage reduction under

(G = grain; L+S = leaves and stems; R = root) of soybean under field conditions (mg/kg)\*

phosphorus removals (P2O5/ha) by soybean were 56 and 78, respectively.

**9.3 Soil tillage** 

2001)

comparison with ZT (Table 22).

conditions of calcareous chernozem.

Stipesevic et al. (2009) reported response of winter wheat and soybean to different soil tillage systems on chernosem soil for four years. Three applied soil tillage treatments were applied as follows: a) CT – conventional soil tillage, based on mouldboard ploughing, b) DH – soil tillage based on diskharrowing instead of ploughing; and c) NT – no-tillage. Both crops showed decreasing concentration of Zn within the plant tissue as a result of the soil tillage reduction in the order CT>DH>NT, presumably due to the limited roots growth in lesser disturbed soil at DH and NT treatments. Winter wheat recorded generally lower than optimal Zn concentrations and higher P:Zn ratios at reduced soil tillage treatments, as a result of lower Zn uptake. The recommendation for the winter wheat production by reduced soil tillage is additional Zn fertilization, whose exact amounts and way of application shall follow further research.


Table 23. Influences of the growing season and soil tillage on nutritional status of soybean (Jug et al., 2006)
