B.S.MathurRajendra Pratap Singh2024-06-222024-06-221990https://krishikosh.egranth.ac.in/handle/1/5810210774Influence of continuous cropping of maize followed by wheat, fertilization and manuring for the last 31 years on the nitrogen transformations in a sedentary acid red loan mixed hyperthermia typic haplustalf soil was studied. Results reveal that 10 to 16% of total N in the surface soil was in the form of NH-N, 14 to 23% as bound amino acid, 4.6 to 8.3% in serine+threonine and 1.8 to 3.8% as amino sugar. Continuous cropping caused a marked depletion in all the hydrolysable nitrogen fractions compared to the adjacent uncropped soil. Monitoring the reversion of different nitro gen fractions within last ten years indicate a depletion in all the hydrolysable N forms in the order: Hydrolysable + NH (19.3) > Hencosamine (17.3) > Serine+threonine-N (14.8)) Total hydrolysable N (13.1)) Hydrolysable unidentified N (10.6) amino acid-N (5.7). Continuous cropping with application of ammonium sulphate alone showed a decline in amino, unidentified and total hydrolysable nitrogen fractions. Inclusion of phosphates along with nitrogen caused an increase in hexose and non-hydrolysable nitrogen while balanced application of NPK kept the amino-N at a higher level. Balanced application of NPK supplemented with lime caused a depletion of hydrolysable ammonium and an accumulation of serine+threonine and hexosamine form of nitrogen. Organic manuring kept the amino as well as serine+threonine nitrogen at a higher level. Hexamine as well as serine+threonine nitrogen were found to correlate significantly and positively with grain yield of maize. Multiple linear regression analysis suggested a greater dependability of yield of both the crops in sequence on serine+threonine, amino and hydroly sable unidentified nitrogen fractions of soil nitrogen. Incubating the soils of differently fertilized plots where acidity had developed, liming resulted in a significant decline of hydrolysable NH and amino nitrogen + with accompanying increase in hexose, serine+threonine and total hydrolysable nitrogen forms. Rate of nitrification in N, P, K treated plots were relatively slow. Organics alone or in conjunction with fertilizer and/or lime resulted in the enhancement of the rate of nitrification with lower delay period.EnglishThesis