Tillage and residue management for organic carbon sequestration in coconut (Cocos nucifera)-based cropping systems

Abstract

A field experiment was carried out on a garden land clay loam soil at Vellayani, Kerala during 2004-06 to study the effect of cropping systems, residue management and tillage practices on organic carbon sequestration in soils and thereby improvement in soil properties for better growth and production of intercrops in a coconut garden. Among the different cropping systems, coconut ( Cocos nucifera)+pineapple ( Ananas comosus) cropping system maintained the highest organic carbon content of 1.30% at the end of two years, whereas the coconut + maize ( Zea mays L.) system maintained only 1.21% soil organic carbon. Surface mulching with crop residues could maintain organic carbon up to 1.37% by the end of the study, but when the residues were incorporated to soil, the soil organic carbon (SOC) status was only 1.13%. Among tillage practices, reduced till maintained 1.29% organic carbon, whereas the conventional tillage could maintain only 1.22% SOC after two years of study. Improvement in soil properties, like aggregate stability, porosity, bulk density, water-holding capacity etc was observed with the maintenance of soil organic carbon. The improvement in soil properties reflected in better yield and returns. Coco- nut + pineapple cropping system registered the highest B:C ratio of 3.61. Coconut + banana ( Musa spp.) system recorded a B:C ratio of 2.52, whereas coconut + maize recorded the lowest of 1.31. Benefit: cost ratios were better with reduced till practices (2.63) as well as surface mulching of crop residues (2.69).