Interactive effects of water-table depth, rainfall variation, and sowing date on maize production in the Western Pampas

FLORIO EL; NOSETTO MD; MERCAU JL; JOBBAGY EG

AGRICULTURAL WATER MANAGEMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014 vol. 146

0378-3774

Shallow water-tables strongly influence agro-ecosystems and pose difficult management challenges to farmers trying to minimize their negative effects on crops and maximize their benefits. In this paper, we evaluated how the water-table depth interacts with rainfall and sowing date to shape maize performance in the Western Pampas of Argentina. For this purpose, we analyzed the influence of water-table depth on the yields of 44 maize plots sown in early and late dates along eight growing seasons (2004?2012) that we rated as dry or wet. In addition, we characterized the influence of the water-table depth on intercepted radiation and crop water status by analyzing MODIS and Landsat images, respectively. The four conditions we evaluated (early sown-dry growing season, early-wet, late-dry, late-wet) showed similar yield response curves to water-table depth, with an optimum depth range (1.5?2.5 m) where yields were highest and stable (∼11.6 Mg ha−1 on average). With water-table above this range, yields declined in all conditions at similar rates (p > 0.1), as well as the crop water status, as suggested by the Crop Water Stress Index, evidencing the negative effects of waterlogging. Water-tables deeper than the optimum range also caused declines of yield, intercepted radiation and crop water status, being these declines remarkably higher in early maize during dry seasons, evidencing a greater reliance of this condition on groundwater supply. Yield in areas with deep water-tables (>4 m) was significantly reduced to between a quarter and a half of yields observed in areas with optimum water-tables. Rainfall occurred around flowering had a strong impact on maize yield in areas with deep water-tables, but not in areas with optimum depth, where yields showed high temporal stability and independence from rainfall in that period. Our study confirmed the strong influence of water-table on rainfed maize and provides several guidelines to help farmers to take better decisions oriented to minimize hydrological risks and maximize the benefits of shallow water-tables.