Assessment of carbon pools in Inceptisol under potato (Solanum tuberosum) based cropping systems in Indo-Gangetic plains

Abstract

Soil carbon pools play a major role in sustaining agro-ecosystems and maintaining environmental quality as they act as a major source and sink of atmospheric carbon. The long-term effect of manuring and fertilization on accessibility of carbon pools of soil in high intensity rice (Oryza sativa L.)-potato (Solanum tuberosum L.)-wheat (Triticum aestivum L.) and maize (Zea mays L.) -potato-onion (Allium cepa L.) cropping systems in Inceptisol of semi-arid sub-tropical India continuing for 10 years was studied. Soil samples were collected (0-15 and 15-30 cm soil depth) from the treatments comprising control (T1), 100% NPK-Fertilizer (T2), 100% N-Vermicompost (VC) (T3), 50% NPK-Fertilizer + 50% N-Vermicompost (VC) (T4), 100% NPK-Fertilizer + crop residue (CR) (T5), 100% N-Vermicompost + CR (T6). Assessment of carbon pools was done by estimating total soil C (TSC), total soil nitrogen (TSN), C:N ratio, carbon mineralization (Cmin), total polysaccharide (TP) and relationship between these pools. The results showed that the application of 100% N-VC (T3) and 100% N-VC + CR (T6) increased the TSC by 94% and 80%, respectively, over 100% NPK in rice-potato-wheat cropping system, while in maize-potato-onion system, 100% N-VC (T3) increased TSC by 48% over 100% NPK (T2) at 0-15 cm soil depth. The soil C:N ratios were generally wider in case of treatments receiving organic sources. In both the soil depths, the T6 treatment (100% N-VC + CR) had resulted higher C mineralization than the other treatments throughout the incubation period. The stable C was lower in maize-potato-onion system than that in the rice-potato-wheat system. The total polysaccharides was higher in organic amended treatments (T6, T3) over chemical fertilizer treatments in improving the TP content in soil which was related to greater C input.