Effect of Traditional Cultivation Management on CO2 Flux in the Dry Tropical Cropland of South India.

Soils in tropical croplands are becoming degraded because of soil carbon (C) depletion. Local farmers in South India use a specific management of traditional cultivation, i.e., broadcast seeding. However, for sustainable C management, there is no quantitative data on the CO₂ flux under this management. Our objectives were to (1) estimate the annual CO₂ flux, and (2) evaluate the effect of traditional cultivation management (seeding rate) on the CO₂ flux. Our field experiment was conducted in South India, from 2015 to 2017, including two cultivation periods with four cultivation management treatments (traditional cultivation management plot (T), fixed density plot (FD), no thinning plot (NT), and bare plot (B)). The seeding rate in the FD plot was ca. 50% of the T plot. We applied 1.1 Mg C ha⁻¹ farmyard manure just before the experiment as a C input. We found that broadcasting, thinning, and cultivation increased soil moisture, while the CO₂ efflux rate showed no significant difference between treatments throughout the experimental period. This indicates that cultivation management did not affect the CO₂ flux. The total CO₂ fluxes for two years were estimated at 2.2–2.7 Mg C ha⁻¹. Our results indicate that it is necessary to apply larger or more frequent C inputs to prevent C depletion. [ABSTRACT FROM AUTHOR]