Effect of in-situ recycling of sugarcane crop residues and its industrial wastes on different soil carbon pools under soybean (Glycine max) - maize (Zea mays) system

Abstract

A field experiment was conducted during summer 2011-12 at MPKV Farm, Rahuri to evaluate the effect of in-situ recycling of sugarcane crop residues and its industrial wastes on soil organic C fractions like labile carbon, microbial biomass C, particulate organic C, KMnO4 extractable C, physically protected particulate organic matter carbon (POMC) and significantly improved water stable aggregates in the cultivated soil under maize (Zea mays L.)-soybean [Glycine max (L.) Merr.] system. The active carbon pools like soil microbial biomass carbon (SMBC), water soluble carbohydrates (WHC) and acid hydrolysable carbon (AHC) was significantly improved in the treatment receiving 100% recommended dose of fertilizer along with in-situ compost of crop residues, press mud cake and methanated spent wash compost compared to burning of residues. Application of in-situ sugarcane residues with pressmud incorporation retainedabout19.6%, 38.8% and 33% more amount of total organic carbon (TOC), SMBC, AHC respectively, over burning of sugarcane crop residues and removal of stubbles after harvest of maize. The mean values of WSC (43 mg/kg) and the physically protected carbon, i.e. POMC (2014 mg/kg) were greater by 47% and 6.6% respectively, in the treatment (T7) receiving in-situ residue decomposition of sugarcane crop residues in combination with equal proportion (50%) of press mud cake and biomethanated spent wash over the burning of sugarcane crop residues and removal of stubbles after harvest of maize. After harvest of maize the maximum recalcitrant fraction (humic acid) of carbon was observed in the treatment T7 (in-situ decomposition of sugarcane crop residues + 50% press-mud cake + 50% biomethenated spent wash). This study clearly indicated that resistant fraction of carbon might be accumulated more where decomposed organic matter was applied regularly. It clearly indicated that application of in-situ decomposed residues and by-products of industrial waste in combination with NPK enhanced the below and above ground biomass production, SOC stock and carbon pools.