Bioresource Nutrient Recycling and Its Relationship with Biofertility Indicators of Soil Health and Nutrient Dynamics in Rice–Wheat Cropping System

A field experiment was conducted for 3 years during 2006–2009 in India to study the effects of plant nutrient recycling through crop residue management, green manuring, and fertility levels on yield attributes, crop productivity, nutrient uptake, and biofertility indicators of soil health in a rice–wheat cropping system. The study revealed that soil microbial biomass carbon (SMBC) and carbon dioxide (CO ₂) evolution were significantly greatest under crop residue incorporation (CRI) + Sesbania green manuring (SGM) treatment and were found at levels of 364 μ g g ⁻¹ soil and 1.75 μ g g ⁻¹ soil h ⁻¹, respectively; these were increased significantly by recycling of organic residues. Activities of dehydrogenase and phosphatase enzymes increased significantly after 3 years, with maximum activity under CRI + SGM treatment. The CRI with or without SGM significantly influenced the plant height, number of tillers m ⁻², number of grains panicle ⁻¹ or ear ⁻¹, and 1000-grain weight. Mean yield data of rice and wheat revealed that CRI or crop residue burning (CRB) resulted in slightly greater yield over crop residue removal (CRR) treatment. The CRI + SGM treatment again observed significantly greatest grain yields of 7.54 and 5.84 t ha ⁻¹ and straw yields of 8.42 and 6.36 t ha ⁻¹ in rice and wheat, respectively, over other crop residue management treatments. Total nitrogen (N), phosphorus (P) and potassium (K) uptake in rice–wheat system was greatest with amounts of 206.7, 37.2, and 205.6 kg ha ⁻¹, respectively, in CRI + SGM treatment. Fertility levels significantly influenced the rice and wheat yield with greatest grain yields of 6.66 and 5.68 t ha ⁻¹ and straw yields of 7.94 and 5.89 t ha ⁻¹ in rice and wheat, respectively, with the application of 150% of recommended NPK. Total NPK uptake in rice–wheat system also increased significantly with increase in fertility levels with greatest magnitude by supplying 150% of recommended NPK. Overall, nutrient recycling through incorporation of crop residues and Sesbania green manuring along with inorganics greatly improved the crop productivity, nutrient uptake, and biofertility indicators of soil health with substantial influence on SMBC, CO ₂ evolution, and dehydrogenase and phosphatase enzyme activities. This indicates that crop residue management along with Sesbania green manuring practice could be a better option for nutrient recycling to sustain the crop productivity and soil health in intensive rice–wheat cropping system in India as well as in similar global agroecological situations, especially in China, Pakistan, and Bangladesh.