EFFECT OF INTEGRATED NUTRIENT MANAGEMENT PRACTICES ON SOIL MICROBIAL POPULATION IN A SOYBEAN-WHEAT CROPPING SEQUENCE

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1 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 (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

2 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 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 % RDF + FYM % RDF + FYM % RDF + FYM % RDF + PM % RDF + PM % RDF + PM % RDF + PM % RDF + BF % RDF + BF % RDF + BF % RDF + BF FYM alone PM alone BF alone Control Fertilizer Organics Interaction NS NS NS NS Ns 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

3 available P 2 O kg ha -1 and K 2 O kg ha -1 ). There were 16 treatments, the details of which are given in Table 1. Then soybean (JS-335) was 80 kg seed/ha in Kharif season and wheat Malav Shakti (HI-8498) was 110 kg seed ha -1 in Rabi season. The fertilizer 20 kg N ha kg P 2 O 5 ha kg K 2 O ha -1 in soybean 100 kg N ha kg P 2 O 5 ha 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 5 g/kg of seed by standard method while PSM was 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 % RDF + FYM % RDF + FYM % RDF + FYM % RDF + PM % RDF + PM % RDF + PM % RDF + PM % RDF + BF % RDF + BF % RDF + BF % RDF + BF FYM alone PM alone BF alone Control Fertilizer Organics NS NS Interaction NS NS NS NS NS NS 161

4 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 % RDF + FYM % RDF + FYM % RDF + FYM % RDF + PM % RDF + PM % RDF + PM % RDF + PM % RDF + BF % RDF + BF % RDF + BF % RDF + BF FYM alone PM alone BF alone Control Fertilizer Organics Interaction NS NS NS NS NS 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

5 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 % RDF + FYM % RDF + FYM % RDF + FYM % RDF + PM % RDF + PM % RDF + PM % RDF + PM % RDF + BF % RDF + BF % RDF + BF % RDF + BF FYM alone PM alone BF alone Control Fertilizer Organics NS NS Interaction NS NS NS NS NS 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

6 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 : (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): (1999). 7. Sriramchandrashekharan M.V., Muthusamy P. and Ravichandra M., Ann. Agric.Res., 16(2), (1995). Say NO to plastic Bags YES to Cloth, Jute and paper Bags. 164