Effect of long term manuring and fertilization on carbon sequestration in terrace soil

A laboratory incubation study was carried out to study the influence of long term manuring and fertilization on soil organic matter (SOM) quality by means of C mineralization in terrace soil of Bangladesh.

Soil samples were collected in 2016 from a highly weathered terrace soil with rice-wheat cropping pattern at Bangabandhu Sheikh Mujibur Rahman Agricultural University experimental farm having five OM (control, cow dung, green manure, rice straw and compost) treatments combined with three mineral N fertilizer (control, 155 kg ha^-1, 220 kg ha^-1) levels. A model was used to explain detected C mineralization in soil known as parallel-first and zero order kinetic model.

Long term (28 years) application of mineral fertilizers and manure resulted that all the estimated parameters were not significantly influenced by either manure application or N fertilization except C mineralization rate was constant for resistant carbon pool (k_s). The k_s value was significantly influenced by manure application. Cumulative annual C mineralization evolved from SOM under field conditions were estimated between 6.21 to 9.31% of total soil organic carbon. The annual carbon mineralization was found to be significantly influenced by different exogenous organic matter application but not with N fertilization. There was a significant difference in annual C mineralization between green manure, cow dung and compost. However, the annual C mineralization was statistically similar between control and green manure treated soil. This result indicates that more stable organic matter was formed in compost treated soil which is less prone to decomposition if present crop management has been changed.