Effect of Long-term Fertilization and Manuring on Soil Enzyme Activity in Rice-rice Cropping System in Semi-arid Southern India

Nutrient management practices have huge influence on soil biological health. The present study was conducted during kharif-2021 in the on-going AICRP on LTFE after 21 years of continuous application of fertilizers and manures to estimate the enzymatic activities i.e., urease and dehydrogenase activity at different growth stages of rice crop. In all the treatments, enzymes exhibited higher activity at flowering stage and thereafter the activity was decreased towards harvesting stage of the rice crop. Among all the treatments, FYM and 100% NPK+FYM treatments recorded highest dehydrogenase and urease activity, respectively as compared with all other treatments. Balanced fertilizer application i.e., 100% NPK also recorded significantly higher enzymatic activity compared with imbalanced fertilizer treatments i.e., 100% N and 100% NP during all the stages of crop growth period. Integrated nutrient management (100%NPK+FYM), FYM and 100% NPK are the best treatment with respect, to increasing enzymatic activity as compared with all other treatments. Grain yield of rice varied from 4078 kg ha-1 to 6569 kg ha-1during kharif-2021. Among all the treatments, maximum grain yield (6569 kg ha-1) was obtained with 100% NPK+FYM. Lower grain yield (4078 kg ha-1) was recorded in the treatment 100% N. Integrated use of inorganic fertilizer and organic manure resulted in higher growth parameters and maximum yield of rice. The combined use of organic as well as inorganic source of plant nutrients could be a sustainable option for optimizing the yield of rice in rice-rice cropping system in semi-arid southern India.