Effect of intra-irrigation meteorological variability on seasonal center-pivot irrigation performance and corn yield

Water application depth of a center-pivot (CP) irrigation system is not uniformly distributed across a field due to emitter package design, tower dynamics, and meteorological variability. The objective of this research was to measure and model the effect of the intra-irrigation meteorological variabilities on CP seasonal water distribution pattern and corn yield. The 2013 irrigation season of a commercial CP cropped with corn was analyzed. From 60 irrigation events applied to the corn, 10 were evaluated using radial catch cans. The mechanical movement of CP towers for the sixty irrigation events was characterized using Global Navigation Satellite System-Real Time Kinematic (GNSS-RTK) monitoring. Meteorological variables at 1s frequency were measured with an automatic weather station installed in the farm. The ballistic model calibrated and validated for rotating spray plate sprinklers under different nozzle sizes and wind conditions was mounted on the CP lateral, following the correspondent sprinkler package. The CP lateral was moved following the measured or simulated tower dynamic, and the current or averaged meteorological conditions of each irrigation event were applied to the corn. Crop yield was simulated by coupling the water distribution pattern simulated under the different cases with the Ador-crop model. Differences were observed for simulated seasonal water distribution pattern of the CP under homogeneous wind conditions (averaged for each irrigation event) or under variable of time wind conditions (measures). Simulated yield considering discontinuous tower dynamics and intra-irrigation meteorological variability has the largest correlation coefficient with the measured corn yield. Other factors were not considered in the yield simulation as variability in nutrient availability, emergence problems, and diseases and soil variability could explain the differences between the simulated and measured corn yield. The intra-irrigation meteorological variability has an important effect on the water distribution pattern of windy irrigation events of CP systems. Depending on the wind speed along the crop season, the intra-irrigation variability will have a major or minor effect on seasonal water distribution pattern and crop yield variability.