Singh, HemlataPRADHAN, BOBBY2023-02-032023-02-032022M/SS/082/2020-21https://krishikosh.egranth.ac.in/handle/1/5810193174The primary key to determining whether a system, like the rice-wheat cropping system is sustainable is through conducting a long-term experiment. Recently, a variety of factors, primarily the burning of crop residues have raised concerns about the sustainability of this system. In addition to that the increasing deficiency of zinc in calcareous soils has led to a decrease in overall crop yields. In this light, a long term field experiment was started under AICRP on “Microsecondary and pollutant elements in plants and soils” in Zn deficient calcareous soil at RPCAU Research Farm, Pusa in a split plot design with main plot divided into four crop residue levels @ 0, 25, 50 and 100% and sub plots into four levels of Zn @ 0, 2.5, 5.0 and 10 kg Zn ha-1 under rice- wheat cropping system. While Zn was applied as a starter dose at the beginning of the experiment and then again after 25 years, crop residue was incorporated following harvest of each crop. The yield of 28th rice crop was recorded and the post-harvest soil samples were used for the evaluation of biological parameters such as soil enzymatic activities (dehydrogenase, phosphatase, urease and glucosidase), soil microbial biomass carbon, soil respiration, chemical parameters such as pH, EC, available nutrients and nutrient uptake in rice grain and straw was also calculated. The activities of all the studied enzymes viz. dehydrogenase , phosphatase, glucosidase and urease were found to be highest with the application of 100% crop residue incorporation and 5 kg Zn ha-1 and was at par with the application of 10 kg Zn ha-1. Soil microbial biomass carbon and soil respiration were highest under 100% crop residue incorporated plots. The total uptake of nutrients viz. N, P, K, Zn by rice crop and post-harvest soil nutrient status were significantly improved with 100% crop residue application. A highly positive correlation between soil enzyme activities, yield and nutrient uptake was also obtained suggesting the positive role of crop residue incorporation in soil. The incorporation of 100% crop residues in combination with 10 kg Zn ha-1 recorded the highest overall rice grain and straw yield followed by 100% incorporation of crop residues with 5 kg Zn ha-1.EnglishThesis