The Role of Plant Nutrition in Narrowing Yield Gaps in Global Wheat Production.

Meeting the food demand of our growing population will require significant reductions in global yield gaps that currently exist.  Wheat is a staple in almost all human diets; however, average grain yields around the world typically range between 20 and 80% of yield potential.  Poor plant nutrition is a major factor contributing to yield losses in farmer fields.  Identifying the role of plant nutrition in current yield gaps will clarify the decision support tools and educational programs that need to be delivered to producers.  Providing growers the information needed to make the right choices regarding sources, rates, timing, and placement of plant nutrients will contribute significantly to narrowing yield gaps in global wheat production.  The objectives of this study were to (1) establish attainable grain yields in major wheat producing countries; (2) establish actual grain yields being obtained in farmer fields and under optimal (non-limiting) fertility conditions; (3) determine the contribution of plant nutrition to current yield gaps.  Attainable yield (YP) was defined for this project as the highest possible yield that can be obtained if limited only by genetic potential, solar radiation, and rainfall.  The CERES-wheat growth model was used to estimate YP for major wheat producing regions in Argentina, Australia, Canada, China, India, Russia, and the United States.  Actual grain yields (AY) were defined as reported, verifiable yield levels obtained at a given location.  Non-fertility limited yields (NLY) were determined using research plot data, e.g. the yield of the optimum treatment in a fertilizer response study.  Data from 2004-2008 were used for this analysis.  Results to be presented include yield gap (YP-AY), non-fertility yield gap [NFYG = (YP-NLY)], and fertility yield gap [FYG = (YG-NFYG)] calculations.