Effects of 38-year continuous manure and fertilizer application on soil Physico-chemical characteristics at various depths in rice-wheat cropping system in Indo-Gangetic plain

A field experiment was carried out in the Bihar region to investigate the long-term effects of organic inorganic fertilizers on the physical and chemical characteristics of soil under the rice-wheat farming system (since 1988–1989) under the programme AICRP-STCR at RPCAU Pusa, Samastipur Bihar, India. It is well known that chemical fertilizers have negative long-term impacts on soils and the environment. Unbalanced nutrients in soils may lead to unproductive soils over time. It is fact that chemical fertilizers alone cannot support crop output that is sustainable, just as applying exclusively organic manure cannot result in increased crop yields. To increase crop productivity and maintain higher yields over time, a combination of inorganic fertilizer and organic manure is needed. A pH of 7.83 to 8.35, an organic carbon concentration between 0.21 and 0.30 dSmˉ1 and percent of 0.44 to 0.78 were found in the surface layer, while 8.63 to 8.15, 0.18 to 0.25 dSm-1, and 0.34 to 0.65 percent were found in the subsurface layer. A combination of NPK and organic residues increased pH, EC, and organic carbon.