Agronomic Learnings from Progressive Wheat Growers in Kansas Who Have Decreased the Yield Gap.

Closing yield gaps (YG) through improved agronomic management will be crucial to increase wheat (Triticum aestivum L.) production and help meet future food demand while minimizing environmental impacts. We analyzed a unique management-by-yield database comprised of 91 intensively-managed fields entered in the Kansas wheat yield contest during the 2010-2016 seasons to identify opportunities to minimize wheat YG. Descriptive statistics quantified typical management practices, and management-yield relationships were explored using Pearson’s correlation coefficient; linear, multiple, and quantile regression analyses; and t-tests between high- and low-yielding fields determined as terciles in the dataset. Water-limited yield (Y_w) was simulated for each harvest year at 30 representative locations across Kansas using a validated crop model, and YG calculated by for each field and weighted by harvested area in the county where the field was located. Wheat grain yield averaged 5.4 Mg ha^-1 among seasons and fields, which corresponded to 90.6% of the simulated Y_w or an average yield gap of 0.74 Mg ha^-1. No-till, in-furrow phosphorus (P) fertilizer, variety maturity, and flag leaf foliar fungicide positively affected grain yield. Varieties with greater susceptibility to fungal diseases significantly responded to foliar fungicide while resistant varieties did not. Early-season fungicide application showed no yield benefit within our dataset. Maximum yield (quantile: 0.99) was 7.3 Mg ha^-1 and was decreased in 1.9 Mg ha^-1 for every one million seeds ha^-1 increase in seeding rates above 2.8 million seeds ha^-1. Wheat grain yield did not respond to fertilizer rate, which highlights an opportunity to decrease environmental impacts by using soil tests to determine fertilizers requirements. Our research explored a unique database of commercial wheat fields that approached the Y_w and highlighted both those management practices that increased or failed to increase grain yields, possibly improving current recommendations for a sustainable intensification of wheat production.