Slow and fast-growing soybean rhizobial population, their symbiotic efficiency and soil nitrogen behavior under different cropping systems in Vertisols of Madhya Pradesh, India
2018
Kumar, Vinod | Rawat, A.K. | Rao, D.L.N.
An attempt was made in this study to assess the indigenous composition (slow and fast-growers) of soybean-rhizobia, their symbiotic efficiency and nitrogen fixation in Vertisols of Madhya Pradesh under different cropping systems. The soils were collected from soybean-based (soybean-wheat and soybean-chickpea) and cereal-based (maize-wheat, rice-wheat and maize-chickpea) systems during 2013–15 from two agro climatic zones of the state. One of the sampling sites was under Long Term Fertilizer Experiment with soybean-wheat system where three treatments-absolute control, recommended dose of fertilizers (RDF) and RDF+FYM were considered. Ratio of fast-growing soybean rhizobia was more in those cropping systems where soybean was one of the crops while population of slow-growers was more with cereal-cereal or maize-chickpea cropping systems. Nodulation and N symbiotic efficiency (N content and uptake) was better with slowgrowing rhizobia as compared to fast-growing. Maximum SOC was found at maximum vegetative growth stage in soybeanwheat rotation (5.7 g kg⁻¹ soil) under RDF+FYM and minimum (3.2 g kg⁻¹ soil) in absolute control. Available soil N was more in kharif season with soybean. Legume based systems and rabi season reflected better conversion of NH₄⁺ to NO₃⁻-N.
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