Narendra KumarDas, Shrila2016-07-122016-07-122011-09http://krishikosh.egranth.ac.in/handle/1/68659Thesis-PhDTwo field experiments were conducted during kharif season of 2008-09 on soybean variety PS1347 at the Norman E. Borloug Crop Research Center of G.B. Pant University of Agriculture and Techonology, Pantnager (Uttarakhand) and one laboratory experiment to evaluate the “Effect of nutrient management and post-emergence herbicides on Glycine max - Rhizobium symbiosis and soil properties” In first experiment, 50% organic + 50% inorganic nutrient sources showed highest nodule number, nodule dry weight, significantly more plant dry weight and grain yield of 1797.91 kg ha-1 and straw yield of 3106.94 kg ha-1 over 100 % organic treatment. This treatment also recorded highest N and P content in grain and straw as well as uptake of N (121.61 kg ha-1) by grain and straw (58.12 kg ha-1) and uptake of P (11.85 kg ha-1) by grain and by straw (13.83 kg ha-1). Maximum number of soil bacteria (23.20 X 107 CFU g-1 soil) and actinomycetes (46.84 x 106 CFU g-1 soil) was found in 50 % organic + 50 % inorganic treatment at 60 DAS. However, maximum fungal population (13.75 x 105 CFU g-1 soil) was recorded after harvest. This treatment also gave higher number of soil rhizobia and PSB than 100 % inorganic treatment at both the intervals. The highest soil available N (286.94 kg ha-1), P (23.46 kg ha-1) and K (139.03 kg ha-1) were recorded in 50 % organic + 50 % inorganic treatment. 100% inorganic and INM+IPM treatments were better than 100% organic for nodule number, nodule dry weight, plant dry weight, yield and N and P content and uptake, but soil microbial population, microbial biomass and dehydrogenase activity were higher in 100% organic treatment than 100% inorganic and INM + IPM treatments. The cropping systems did not significantly affect nodule number, nodule dry weight, grain and straw yields, and N and P content and uptake. However, significantly more plant dry weight was recorded in soybean-chickpea cropping system than soybean-wheat. The population of soil rhizobia and phosphate solubilizing bacteria (PSB), microbial biomass carbon were significantly higher in soybean-chickpea cropping system in comparison to soybean-wheat system after harvest. The cropping systems did not show significant effect on soil organic carbon, pH, electrical conductivity, bulk density and available N, P and K. Interactions between nutrient management and cropping systems were significant for nodule number at 60 and 90 DAS, nodule and plant dry weight at 30 and 90 DAS, grain and straw yields, N content and uptake by grain and straw, P content and uptake by grain. Significant interactions between nutrient management and cropping systems was also recorded for total soil bacteria, actinomycetes and PSB population after harvest, total fungal, rhizobial population and microbial biomass carbon and dehydrogenase activity in soil at 60 DAS and after harvest. In second experiment, maximum nodule number per plant, nodule and plant dry weight, grain yield of 2185.17 kg ha-1 and straw yield of 3018.50 kg ha-1 were found in two hand weeding treatment, while weedy check control showed minimum. The uptake of N and P by grain and straw was significantly more in two hand weeding treatment than all other treatments. This treatment also showed maximum number of soil microorganisms including rhizobia, PSB, microbial biomass carbon and dehydrogenase activity at 60 DAS as well as after harvest. By increasing concentration of haloxyfop ethyl 10 EC from 75 to 100 g a.i. ha-1, decline in soil microbial population, microbial biomass carbon and dehydrogenase activity were recorded at 60 DAS as well as after harvest. Among herbicides, fenoxyprop ethyl 9 EC @ 100 g a.i. ha-1 was found most effective in controlling weeds in soybean and showed better nodulation, plant growth, yield, nutrients uptake and soil health parameters. In third experiment, the increase in concentration of herbicides significantly reduced the population of Bradyrhizobium japonicum and PSB (except 0.3 and 0.4 per cent concentration). Maximum number of Bradyrhizobium japonicum (110.66 X 104 CFU mL-1) and PSB (84.73 X 104 CFU mL-1) was recorded in the control and minimum of 19.57 X 104 CFU g-1 soil and 14.69 X 104 CFU mL-1 soil at 0.5 per cent concentration, respectively.ennutrients, herbicides, soyabeans, glycine max, rhizobium, symbiosis, inoculation, soil biology, soil properties, nutrient uptakeThesis