Agronomic practices for reducing wheat yield gaps: A quantitative appraisal of progressive producers

Abstract

There is limited information on agronomic practices affecting wheat (Triticum aestivum L.) yield in intensively managed dryland systems despite the opportunity to narrow the existing yield gap (Y G ). We used a unique database of 100 intensively managed field-years entered in the Kansas Wheat Yield Contest during the 2010 to 2017 harvest seasons to (i) quantify the Y G , (ii) describe wheat management, and (iii) identify management opportunities and weather patterns associated with yield. We simulated wheat water-limited yield (Y w ) using Simple Simulation Modeling–Wheat (SSM-Wheat) model for each field-year to estimate Y G as the difference between Y w and actual yield (Y a ) and used 11 statistical approaches to test the association of management practices and weather variables with Y a . Wheat Y a averaged 5.5 Mg ha −1 , and simulated Y w averaged 6.4 Mg ha −1 , resulting in a Y G of 0.9 Mg ha −1 (15% of Y w ). High-yielding fields had lower maximum and minimum temperatures and greater cumulative solar radiation and precipitation during grain fill. Varieties susceptible to fungal diseases responded to foliar fungicide (0.8–1.4 Mg ha −1 ), whereas resistant varieties did not. Seeding rate was negatively associated with Y a , as yield quantile 0.99 was 7.5 Mg ha −1 and decreased by 2.7 Mg ha −1 for every 100-seed m −2 increase in seeding rate above 305 seeds m −2 . In-furrow P fertilizer, previous crop, tillage practice, and N timing were also associated with Y a . We conclude that fields entered in yield contests have closed the exploitable Y G , and there are opportunities to improve Y a through improved management in regions with stagnant wheat yield.