Modelled yield and water use efficiency of maize in response to crop management and Southern Oscillation Index in a soil-climate transect in Argentina

Maize responses to individual management factors have been widely investigated but studies of higher-order interactions involving multiple factors are rare. This paper investigates the responses of grain yield and water use efficiency of rainfed maize to sowing date, stubble condition, hybrids of contrasting cycle length, soil depth and their interactions, and how these responses are affected by El Niño - Southern Oscillation (ENSO) phenomenon. Grain yield and water balance were modelled with CropSyst using 33 years of weather data for eight locations in an east-west transect in the Southern Pampas of Argentina. Modelled grain yield decreased westward, in parallel with decreasing rainfall. Southern Oscillation Index (SOI) discriminated crop season rainfall and grain yield, with lower rainfall and grain yield for SOI phase Consistently Positive (CP) and higher rainfall and grain yield for SOI phase Consistently Negative (CN). Differences in grain yield between stubble and bare soil were constant across location. High available water, as related to soil depth, increased grain yield across the transect. The effect of sowing date and stubble varied with SOI phase; for CN, highest grain yields were obtained with early sowing whereas for CP grain yield showed no correlation with sowing date. Yield differences between bare soil and stubble conditions were higher under CP than under CN, reflecting the positive effect of stubble in years with rainfall below average. Water use efficiency (WUE=yield per unit evapotranspiration) averaged 19.0kgha -1mm -1 for soils with stubble and 16.5kgha -1mm -1 for bare soil. We conclude that SOI provides an agronomically meaningful predictor of seasonal conditions that can be used to estimate crop production and manage risk by adjusting key management practices. © 2012 Elsevier B.V.J.P. Monzon, V.O. Sadras and F.H. Andrad