Skip to main content
Dryad

Data for: Nitrous oxide emissions from groundnut and millets farms in semi-arid peninsular India

Data files

Dec 16, 2022 version files 368.65 KB

Abstract

Nitrous oxide (N2O) emissions response curves for crops grown outside temperate regions have been rare and have thus far arrived at conflicting conclusions. Most studies reporting N2O emissions from tropical cropping systems have examined only one or two nitrogen fertilizer application rate(s) which precludes the possibility of discovering nonlinear changes in emission factors (EF, % of added N converted to N2O-N) with increasing fertilizer-N rates. To examine the relationship between N rates and N2O fluxes in a tropical region, we compared farming practices with three or four N rates for their yield-scaled impacts from three crops in peninsular India. We measured N2O fluxes during nine seasons between 2012 and 2015, with N application rates ranging between 0 and 70, 0 and 90, and 0 and 480 kg-N ha-1 for foxtail-millet (Setaria italica L., locally called korra), groundnut (Arachis hypogaea L., also called peanut) and finger-millet (Eleusine coracana L., locally called ragi), respectively. In two cases, the highest N application rate greatly exceeded crop-N needs. Potential climate smart farming agricultural practices (with low/optimized N rates) led to a 50-150% reduction in N2O emissions intensity (per unit yield) along with a reduction of 0.2-0.75 tCO2e ha-1 season­­-1 as compared to high N conventional applications. We found a non-linear increase in N2O flux in response to increasing applied N for both N-fixing and non N-fixing crops and the extent of super-linearity for non N-fixing crops was much higher than what has been reported earlier. If a linear fit is imposed on our datasets, the emission factors (EFs) for finger-millet and groundnut were ~3.5% and ~1.8%, respectively. Our data shows that for low-N tropical cropping systems, even when they have low soil carbon content, increase in N use to levels just above crop needs to enhance productivity might lead to relatively small increase in N2O emissions as compared to the impact of equivalent changes in fertilizer-N use in systems fertilized far beyond crop N needs.