Long-term effects of erosion and climate interactions on corn yield

ABSTRACT:

An accurate assessment of the impacts of soil erosion on corn production is needed for conservation and management programs. Climatic variability produces a range of crop yield responses on eroded and non-eroded soil profiles and often masks the long-term trends and differences. Short-term corn yield data from representative soils across the North Central region were supplemented with calculated yields from the NTRM model to develop long-term yield responses for the historical climate records at each of seven highly-managed rainfed sites across the region. Results showed that long-term average regional corn yields were reduced by 10% for severely eroded versus control plots. Till-derived soils showed yield reductions averaging 12%, while loess soils lost an average of 7%. Sensitivity runs with the NTRM model made after field validation with 119 plot-years of data suggested that changes in soil physical properties, especially plant-available water holding capacities, probably accounted for most of the yield differences. Mean growing season (May-September) precipitation across all sites for the short-term field study was 35.3 cm, compared with 36.3 cm for the long-term historical record. This resulted in a mean short-term corn yield reduction of 9% for severely eroded soils versus a reduction of 10% for the same soils based on long-term climate projections. However, the close agreement between the short- and long-term studies with regard to mean growing season precipitation and corresponding corn yields should not be used to make the general conclusion that 3 to 6 years is an adequate time period for field research on long-term crop response to eroded soil conditions.