Modeled El Niño‐Southern Oscillation Effects on Grain Sorghum under Varying Irrigation Strategies and Cultural Practices

Abstract

Core Ideas Maturing Oceanic Niño Index identified La Niña years with less rain and yield.Increased irrigation plus rain improved yield but water use efficiency plateaued.Irrigation of partitioned areas with dryland improved yield independent of El Niño southern oscillation phase. Equatorial sea surface temperatures vary systematically to cause the El Niño southern oscillation (ENSO) that produces predictable weather patterns in North America and may permit long‐range climate predictions and eventual proactive summer crop irrigation management. The declining Ogallala Aquifer in the Southern High Plains and consequently limited well capacities challenge producers to adapt cropping practices for irrigation that doesn’t meet crop water demand. Our objective was to evaluate sorghum [Sorghum bicolor (L.) Moench] yield response to ENSO climate‐informed management of cultural practices and irrigation strategies on a Pullman soil (fine, mixed, superactive, thermic Torrertic Paleustoll). We used the simulation model SORKAM and long‐term (1961–2000) weather records from Bushland, TX, classified by ENSO phase to calculate sorghum grain yields for all combinations of irrigation levels (0.0, 2.5, 3.75, or 5.0 mm d−1), planting day of year (DOY = 135, 156, 176), and cultivar maturity (early, 95 d; medium, 105 d; late, 120 d). Using the September–November Oceanic Niño Index (ONI) to identify ENSO phase, La Niña years had 50 mm less precipitation and a corresponding 14.5% reduction in overall yield to 4550 kg ha−1 for sorghum planted at 16 plants m−2 population. Late maturing cultivars and late planting led to sorghum freeze injury and reduced yields regardless of ENSO phase. While yields consistently increased with irrigation, we conclude that concentrating water to irrigate an area partitioned 2:1 or 1:1 at 3.75‐ or 5.0‐mm d−1 with complementary dryland produced >30% more grain, overall, than uniformly irrigating an area at 2.5 mm d−1.