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R. B. Nazirkar ¹, Smita P. Rakhunde ¹, Ritu Thakare ¹

Affiliations
1 Department of Soil Science and Agricultural Chemistry, College of Agriculture, Dhule (M.S.), IN

Abstract

An incubation study under ambient conditions and simultaneously pot culture experiment on soybean was conducted to observe the availability of phosphorus from rock phosphate due to acidulation effect caused by the sulphure and microorganism like PSB and EM. It was to ascertain the possibility of making use of rock phosphate (low grade) for direct use in soil application were tested in highly phosphorus consumptive soybean crop. The RP @ 75 kg ha was applied in the soil (3 kg) in bowl. The treatments were comprised of application of graded levels of elemental S (0, 30, 60 kg ha^-1) with and without PSB or EM or PSB + EM. The soils were incubated for 90 days under ambient condition with keeping moisture at field capacity. The results indicated that highest available phosphorus content in RP + S₆₀ + PSB which was at par with RP + S₃₀ + PSB + EM, suggests that 30 kg S along with PSB and EM was the best treatment for phosphorus release through solubilization of RP and increase availability of phosphorus to soybean.

Keywords

Rock Phosphate, Available Phosphorus, Sulphur, Microorganism.

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Ritu Thakare ¹, Sanjay Bhoyar ²

Affiliations
1 Department of Soil Science and Agricultural Chemistry, College of Agriculture, Dhule (M.S.), IN
2 Department of Soil Science and Agricultural Chemistry, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola (M.S.), IN

Abstract

The integrated use of crop residues, biofertilizer and inorganic fertilizers in vertisol improved fertilizer use efficiency and nutrient turnover through augmentation of biological activity specially enzyme activity which is a step toward sustainable agricultural production. Highest soil microbial biomass C (340.25 μg Cg^-1 soil) and biomass N (30.15 μg N g^-1 soil) were recorded in Bradyrhizobium + 100% RDF i.e. 30 kg N + 75 kg P₂O₅ ha^-1 treatment followed by incorporation of wheat straw @ 4 t ha^-1 + 100% RDF. Incorporation of wheat straw and sugarcane trash along with chemical fertilizer significantly increased SMBC and SMBN content over their alone application. There was significant influence of crop residues and biofertilizer on soil enzyme activity i.e. dehydrogenase activity over control. Incorporation of wheat straw @ 4 t ha^-1 + 100% RDF significantly increased soil dehydrogenase activity as compared to all other treatments. Bacterial and actinomycetes population were found maximum i.e. 29.6 CFU g^-1 × 10⁷ and 25.0 CFU g^-1 × 10⁶, respectively in seed treatment with Bradyrhizobium + 100% RDF, whereas, fungal population was found to increase (21.4 6 CFU g^-1 × 10⁴) with the incorporation of wheat straw @ 4 t ha^-1 + 100% RDF followed by sugarcane trash with 100% RDF. Seed inoculation with Bradyrhizobium with 100% RDF recorded highest grain yield (24.59 ha^-1) and was followed by wheat straw + 100% RDF. SMBC, SMBN, dehydrogenase activity and soil biota were significantly correlated with soybean yield.

Keywords

Soil Microbial Biomass Carbon and Nitrogen, Soil Microbial Population, Dehydrogenase Activity, Integrated Nutrient Management, Vertisol.

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