Long-term effect of fertilizers and manure application on soil organic carbon dynamics under rice-wheat cropping system in Inceptisol.

Abstract

Decline in soil fertility, low crop productivity and sustainability issues warned much attention for improving soil health and environment. Studied on soil organic carbon and its dynamics for long term restoration of soil health, maximizing crop production and reducing environmental pollution. In view of this, studies were planned to investigate long-term effect of fertilizer and manure application on soil organic carbon dynamics and their impact on sustainability of rice – wheat cropping system in an Inceptisol of Varanasi since 1985. Balanced and integrated use of 50 % NPK + 50 % N through FYM/ ha not only sustained the higher grain yield compared to control 50 % NP and 100 % NPK alone but also helped in sustaining high fertility status of soil. Studies on soil organic carbon (SOC) pools and dynamics revealed that active pools of carbon and water soluble carbohydrates in soil increased by 57 % (0.28- 0.44 %) and 190 % (344.16 – 654.85 ppm) in surface soil depth (0-15 cm) compared to SOC content in control. The soil microbial biomass carbon comprised 3.8 – 6.8 % of SOC, 3.0 – 3.4 % of soil N. The adverse effects of imbalanced application of either NP or NPK without manure decrease productivity of rice-wheat cropping system such Inceptisol.