Modeling Nitrous Oxide Emissions From Large-Scale Intensive Cropping Systems in the Southern Amazon

Nitrogen (N) fertilizer use is rapidly intensifying on tropical croplands and has the potential to increase emissions of greenhouse gas, nitrous oxide (N 2 O). Since about 2005 Mato Grosso (MT), Brazil shifted from single-cropped soybeans double-cropping with maize, now produces 1.5% world's maize. This production shift required an in N fertilization, but effects O are poorly known. We calibrated process-oriented biogeochemical DeNitrification-DeComposition (DNDC) model simulate crop soybean soybean-maize cropping systems MT. After validation field measurements adjustments for hydrological properties soils, regional simulations suggested cropland increased almost fourfold during 2001–2010, 1.1 ± 4.1 3.2 Gg 1014 N-N O. Model sensitivity tests showed that were spatially seasonably variable especially sensitive soil bulk density carbon content. Meeting future demand maize using current area MT might require either (a) 3.0 million ha existing single or (b) increasing fertilization ~180 kg −1 2.3 area. The latter strategy would release ~35% more than first. Our modifications DNDC will improve estimates agricultural other areas, narrowing uncertainty depend detailed spatial data management.