EFFECT OF INTEGRATED NUTRIENT MANAGEMENT PRACTICES ON SOIL MICROBIAL POPULATION IN A SOYBEAN-WHEAT CROPPING SEQUENCE V.K. Khaddar* and Shivaji Yadav Department of Soil Science and Agricultural Chemistry, JNKVV, College of Agriculture, Indore - 452 001 (INDIA) Received June 20, 2006 Accepted October 26, 2006 ABSTRACT A field trial for two consecutive years (1999 and 2000) at Research Farm, College of Agriculture, Indore (India) was conducted in factorial randomized block design with sixteen treatments replicated three times in a soybean-wheat cropping sequence. The microbial population in soil was estimated by dilution plate count method. Application of biofertilizers significantly showed higher bacterial population during both the years of study. The fungal population increased in treated plot over control. Among the organics, biofertilizer increased fungal population at 25 day stage of the crop, while there was slight decrease in fungal population. Integrated use of chemical fertilizer with organics could ameliorate the soil and improve the productivity of a soybean-wheat cropping sequence resulting in eco-friendly farming system. Key Words : Bacterial population, fungal population, poultry manure, farmyard manure, biofertilizer, wheat, soybean, fertilizer. INTRODUCTION Fertility of soil is very important for obtaining optimum production of crops. The role of organic matter in enhancing and maintaining soil fertility and productivity is universally understood. The absence of organic matter from soil causes unproductive soil. Organic matter induces life into the soil and sustains biological life. In order to attain sustained production of crops, recycling of organic matter in the soil should become a regular feature of *Author for corospondence. 159
through optimization of the benefits from all possible sources of plant nutrients in an integrated manner. 4 The chemical fertilizers are also responsible for creating heavy metal pollution in soil and the higher doses of chemical fertilizers deteriorate the buffering capacity of soil and increase the ill effects of chemical fertilizers. To know the effect of organics on such properties, a field trial was conducted for two consecutive years (1999 and 2000) to assess the microbial population of soil and its effect on soybean-wheat cropping sequence. MATERIAL AND METHODS A field experiment in factorial randomized block design with three replications was planned to study the effect of organics in combination with chemical fertilizer on microbial population in a soybean-wheat cropping sequence for two consecutive years (1999 and 2000) at Research Farm, College of Agriculture, Indore (India). The soil under study was clay (10.40% sand, 36.00% silt, 53.60% clay) with 7.58 ph and 0.22 dsm -1 electrical conductivity (available N 228.58 kg ha -1, Table 1. Effect of chemical fertilizers, organics and biofertilizers on mean fungal population (10 4 g -1 soil) at different stages of wheat crop Mean fungal population (10 4 g -1 soil) at different stags of wheat crop 125% RDF + FYM 31 30 11 30 29 12 100% RDF + FYM 33 28 12 32 30 14 75% RDF + FYM 25 24 11 29 24 12 50% RDF + FYM 22 20 10 26 21 11 125% RDF + PM 32 21 13 30 25 14 100% RDF + PM 30 27 11 32 28 13 75% RDF + PM 22 22 10 25 24 11 50% RDF + PM 21 18 05 24 22 09 125% RDF + BF 30 32 12 31 31 13 0 100% RDF + BF 32 34 11 33 32 12 1 75% RDF + BF 31 28 09 30 30 10 2 50% RDF + BF 25 22 11 29 29 12 3 FYM alone 27 23 12 30 26 14 4 PM alone 30 28 11 32 28 15 BF alone 35 30 12 39 30 20 Control 15 12 07 16 12 08 Fertilizer 0.831 2.399 0.860 2.483 0.812 2.344 0.801 2.313 0.860 2.483 0.800 2.310 Organics 0.642 1.853 0.669 1.931 0.630 1.819 0.640 1.848 0.669 1.931 0.600 1.732 Interaction 1.448 NS 1.480 NS 1.412 NS 1.430 NS 1.401 Ns 1.400 NS PM = Poultry manure 2.5 t ha -1, BF = Biofertilizer (Rhizobium 5 g kg -1 of seed + 7 kg ha -1 PSM mixed with soil); FYM = Farm yard manure 10 t ha -1, RDF = Recommended dose of fertilizer 160
available P 2 O 5 11.123 kg ha -1 and K 2 O 542.30 kg ha -1 ). There were 16 treatments, the details of which are given in Table 1. Then soybean (JS-335) was sown @ 80 kg seed/ha in Kharif season and wheat Malav Shakti (HI-8498) was sown @ 110 kg seed ha -1 in Rabi season. The fertilizer doses @ 20 kg N ha -1 + 60 kg P 2 O 5 ha -1 + 20 kg K 2 O ha -1 in soybean and @ 100 kg N ha -1 + 40 kg P 2 O 5 ha -1 + 40 kg K 2 O ha -1 in wheat were applied through urea, single super phosphate and muriate of potash respectively before sowing. The desired doses of FYM and PM prepared and collected from the College Farm and were applied in the field before 10 days of sowing. The soybean seeds were inoculated with Rhizobium inoculant @ 5 g/kg of seed by standard method while PSM was mixed @ 7 kg ha -1 and applied to the furrows just before sowing of seed. Soil samples were collected from 0-15 cm depth at different growth stages of both the crops, the bacterial and fungal population in the collected soil samples was monitored employing the standard serial dilution Table 2. Effect of chemical fertilizers, organics and biofertilizers on mean bacterial population (10 5 g -1 soil) at different stages of wheat crop Mean bacterial population (10 4 g -1 soil) at different stags of wheat crop 125% RDF + FYM 168 198 127 170 200 130 100% RDF + FYM 160 195 125 162 198 129 75% RDF + FYM 151 192 117 150 197 120 50% RDF + FYM 138 188 114 142 192 117 125% RDF + PM 167 199 120 170 210 128 100% RDF + PM 162 201 118 169 207 125 75% RDF + PM 158 197 114 160 201 120 50% RDF + PM 138 192 110 146 199 119 125% RDF + BF 172 210 128 171 212 130 0 100% RDF + BF 159 209 120 160 210 127 1 75% RDF + BF 150 200 116 152 202 122 2 50% RDF + BF 145 191 119 148 194 120 3 FYM alone 160 197 129 164 200 131 4 PM alone 168 194 121 170 214 138 BF alone 174 201 130 180 225 135 Control 60 90 50 80 100 66 Fertilizer 0.780 5.140 1.667 4.813 1.200 3.465 1.780 5.140 1.670 4.822 1.201 3.468 Organics 1.362 3.933 1.287 NS 0.928 2.699 1.380 3.984 1.221 NS 0.900 2.598 Interaction 3.089 NS 2.887 NS 2.086 NS 3.017 NS 2.889 NS 2.090 NS 161
Table 3. Effect of chemical fertilizers, organics and biofertilizers on mean fungal population (10 4 g -1 soil) at different stages of wheat crop and plate count method. 5 The data were subjected to statistical analysis to draw significance of the treatments. RESULTS AND DISCUSSION Among all the treatments, the control plot showed the minimum count of bacterial population over treated plot at 75 days after sowing for both crops (Table 1 to 4). The FYM treated plot registered the maximum bacterial population at all the three stages while it was slightly higher in case of biofertilizer at all the three stages. Mean bacterial population (10 4 g -1 soil) at different stags of wheat crop 125% RDF + FYM 32 30 15 31 32 14 100% RDF + FYM 34 32 16 34 35 17 75% RDF + FYM 30 28 14 32 30 15 50% RDF + FYM 27 25 13 30 27 12 125% RDF + PM 31 29 15 30 28 14 100% RDF + PM 33 30 15 34 33 13 75% RDF + PM 28 26 13 30 28 12 50% RDF + PM 26 24 12 27 25 10 125% RDF + BF 35 33 18 35 34 17 0 100% RDF + BF 37 35 19 38 36 20 1 75% RDF + BF 34 32 16 35 33 15 2 50% RDF + BF 32 30 14 31 30 14 3 FYM alone 34 32 16 35 32 17 4 PM alone 36 34 17 38 36 18 BF alone 42 39 21 45 40 23 Control 18 16 09 19 17 11 Fertilizer 0.837 2.416 0.865 2.497 0.819 2.365 0.835 2.411 0.862 2.489 0.816 2.356 Organics 0.649 1.874 0.670 1.934 0.634 1.830 0.645 1.862 0.671 1.938 0.632 1.825 Interaction 1.450 NS 1.499 NS 1.418 NS 1.452 NS 1.496 NS 1.418 NS 162 Application of biofertilizer significantly showed higher bacterial population over other two organics e.g. poultry manure and farmyard manure, at all the three stages except at 25 days stage. The increasing dose of chemical fertilizer slightly decreased the bacterial population during both the years of study. The higher number of fungal and bacterial population were observed at 50 DAS over 25 and 75 DAS stage (Table 2) in both the years of study. The fungal population in soybean at different stages indicated significant increase
Table 4. Effect of chemical fertilizers, organics and biofertilizers on mean bacterial population (10 5 g -1 soil) at different stages of soybean crop Mean bacterial population (10 4 g -1 soil) at different stags of wheat crop 125% RDF + FYM 174 219 139 175 220 140 100% RDF + FYM 164 212 133 163 211 134 75% RDF + FYM 153 207 125 151 208 126 50% RDF + FYM 143 194 119 140 195 117 125% RDF + PM 176 218 134 174 219 135 100% RDF + PM 170 210 131 169 209 130 75% RDF + PM 163 207 126 160 206 124 50% RDF + PM 148 201 121 145 202 122 125% RDF + BF 172 220 139 170 221 140 0 100% RDF + BF 165 213 136 163 214 135 1 75% RDF + BF 158 206 130 156 207 129 2 50% RDF + BF 150 199 126 151 200 124 3 FYM alone 167 211 137 168 212 138 4 PM alone 174 219 140 175 220 141 BF alone 187 227 147 188 228 148 Control 100 107 88 110 106 866 Fertilizer 1.785 5.154 1.674 4.839 1.208 3.488 1.783 5.148 1.674 4.833 1.206 3.482 Organics 1.383 3.990 1.298 NS 0.936 2.702 1.386 4.002 1.296 NS 0.934 2.697 Interaction 3.092 NS 2.903 NS 2.093 NS 2.901 NS 2.091 NS 2.901 NS in the treated plot over control in both the years of study. Among the organics, biofertilizer increased the fungal population (10 5 g -1 soil) at 25 DAS stage, while there was slight decrease in fungal population with poultry manure application (Table 2). A combination of biofertilizers and chemical fertilizer showed the maximum fungal population at 25 days stage of wheat crop in both the years of study. 6 Increasing dose of chemical fertilizer decreased the fungal population at all the stages during the growth of wheat in both the years of study. The present findings are inconformity with finding of Ramchandrasekharan et al. (1995), they reported that higher doses of chemical fertilizer increased the microbial population, which was observed maximum at flowering and fungi increased up to maturity. Use of organics improved the productivity of both the crops. The microbial population was maintained in soil with the help of organics. 7 Increase in microbial population in the rhizosphere of both soybean 163
and wheat crops in the presence of organics is quite obvious as they act as a source of energy for the proliferation of microorganisms in the soil by virtue of their high organic carbon contents. Besides this the Nitrogen fixing potential of rhizobia in the rhizosphere of soybean phosphate solubilizing potential of PSM in the rhizosphere of both soybean and wheat crops is enhanced, in presence of organics, which might have resulted in increased supply of both N and P to the growing crops. Thus it is concluded that integrated use of organics with chemical fertilizers, ameliorate the soil and improve the productivity of crop, resulting in eco-friendly farming system. CONCLUSION Increasing doses of chemical fertilizers decreased the fungal population at 25 DAS stage in wheat crop. The fungal population in soybean at different stages indicated significant increase in the treated plot over control in both the years of study. Among the organics, biofertilizer increased the fungal population. Increase in microbial population in the rhizosphere of both soybean and wheat crop in presence of organics is obvious and they act as a source of energy. Integrated use of organics with chemical fertilizers, ameliorate the soil and improve the productivity of crop, resulting in eco-friendly farming system. REFERENCES 1. Chowksey V.P., Vaishya V.K., Tembhare, B.R., Rathore G.S. and Johar M.S., JNKVV Res. J.,27(1), 45-48(1995). 2. Choksey V.P. (1991). M.Sc. (Ag.) Thesis submitted to JNKVV, Jabalpur. Day, P.R., Donar HE and Machlaren A.D. Soil in nitrogen in the envirionment, 2 : 305-363 (1978). 3. Johar K.S., Organic farming, JNKVV, Jabalpur 1-3 (1992). 4. Motsara M.R., Bhattacharya P. and Srivastava Beena, A source bookcumglossary, 184 FDCO, New Delhi (1995). 5. Scmidt E.L. and Colwell A.C., A Practical Manual of Soil Microbiology Laboratory Methods. Soil Bull, 7, FAO, Rome (1967). 6. Singh A.K., Ram A. and Maurya B.R., J. Indian Soc.Soil Sci.41(1): 159-169 (1999). 7. Sriramchandrashekharan M.V., Muthusamy P. and Ravichandra M., Ann. Agric.Res., 16(2), 195-200 (1995). Say NO to plastic Bags YES to Cloth, Jute and paper Bags. 164