105141 Which Management Strategies Are Required to Economically Reduce Winter Wheat Yield Gaps?.
Poster Number 406
Tuesday, October 24, 2017
Tampa Convention Center, East Exhibit Hall
Winter wheat (Triticum aestivum L.) yield potential in Kansas averages ~5.2 Mg ha-1; however, state-level yields rarely surpassed 3.4 Mg ha-1. Our objective was to quantify the contribution of individual management practices to economically reduce wheat yield gaps (YG). An incomplete factorial treatment structure established in a randomized complete block design with six replications was used to evaluate 14 treatments during two years in three central Kansas locations. Sites were combined based on tillage practice (no-till, Manhattan, 2016 and 2017; conventional-till, Belleville and Hutchinson, 2016 and 2017). We individually added six treatments to a farmer practice (FP) or removed from an water-limited yield (Yw), which received all treatments. Practices were additional split-nitrogen (N), sulfur, chloride, increased plant population, foliar fungicide, and plant growth regulator. Percent YG was calculated by site-year using the Yw as reference for potential yield. Orthogonal contrasts indicated yield under no-till increased from the FP by the full Yw (+0.37 Mg ha-1), but also by the individual practices split-N (+0.28 Mg ha-1), sulfur (+0.26 Mg ha-1), increased plant population (+0.36 Mg ha-1), and fungicide (+0.18 Mg ha-1). Yield under conventional-till increased by Yw (+1.18 Mg ha-1) largely led by fungicide (+1.44 Mg ha-1). The Yw and split-N increased grain protein concentration in no-till (8.6 and 9.0 g kg-1) and conventional-till (12.3 and 11.5 g kg-1). FP yield gap was 8% in no-till, and was reduced by split-N (6%), sulfur (5%), chloride (3%), increased plant population (8%), and fungicide (4%). FP yield gap was 20% under conventional-till and was reduced by fungicide (25%). Fungicide increased net return (+$106.57 ha-1) under conventional-till, and increased plant population under no-till (+$36.65 ha-1). While a high-cost input (i.e. fungicide) can only economically reduce YG when this is greater than 20%; a low-cost input (i.e. increased plant population) can economically reduce smaller YG.