Spatial variability of nitrous oxide emissions from croplands and unmanaged natural ecosystems across a large environmental gradient.

Atmospheric nitrous oxide (NO) is a potent greenhouse gas, with long atmospheric residence time and a global warming potential 273 times higher than CO. NO emissions are mainly produced from soils and are influenced by biotic and abiotic factors that can be substantially altered by anthropogenic activities, such as land uses, especially when unmanaged natural ecosystems are replaced by croplands or other uses. In this study, we evaluated the spatial variability of NO emissions from croplands (maize, soybean, wheat, and sugar cane crops), paired with the natural grasslands or forests that they replaced across a wide environmental gradient in Argentina, and identified the key drivers governing the spatial variability of NO emissions using structural equation modeling.

Influence of management practices on water-related grain yield determinants.

Adequate management of N supply, plant density, row spacing, and soil cover has proved useful for increasing grain yields and/or grain yield stability of rainfed crops over the years. We review the impact of these management practices on grain yield water-related determinants: seasonal crop evapotranspiration (ET) and water use efficiency for grain production per unit of evapotranspired water during the growing season (WUEG,ET,s). We highlight a large number of conflicting results for the impact of management on ET and expose the complexity of the ET response to environmental factors.