Crop Productivity and Soil Carbon Dynamics under Long-Term Conservation Agriculture in India

Abstract

Given the increasing scarcity of production resources such as water, energy and labor compounded by growing climatic risks – maize based production systems in north - western India are potential alternatives to intensive rice - wheat (RW) rotation. Conservation agriculture (CA) based best - bet crop management practices may increase crop productivity, while conserving and sustaining natural resources. Such practices are also believed to provide mitigation co - benefits through reduced GHG emission and increased soil carbon sequestration. In a nine - year study of conservation agriculture experiment established in 2008, we have evaluated the performance of CA - based management practices [zero tilled permanent bed (PB) and zero tillage flat (ZT)] and conventional till flat (CT) in main plots for four intensified irrigated maize systems [maize - wheat - mungbean (MWMb), maize - chickpea - Sesbania green manure (MCS), maize - mustard - mungbean (MMuMb) and maize - maize - Sesbania (MMS)] in sub plots. The experimental design was split - plot with three replications. Significant (P<0.05) tillage and cropping system interactions were observed for cropping system productivity and carbon dynamics. Agronomic performance (yield attributes) of all the crops (except wheat) grown in sequence with maize was maximum with ZT. Wheat outperformed on PB over ZT and CT. In the initial two years, higher system productivity (maize equivalent yield) was recorded in PB (8.2 - 8.5 Mg ha - 1). The soil organic carbon (SOC) content and its fractions were greatly affected by tillage, and crop establishment methods and cropping systems. The ZT and PB based crop establishment methods increased more SOC stock (0−30 cm) than CT system compared to initial value.