How Does Management Increase Soybean Seed Protein? A Mechanistic Approach to Identifying Limitations and Opportunities

Developing strategies that ensure protein quantity and quality of U.S. soybean is competitive in global markets is essential for our producers. This involves a minimum total protein and increased levels of essential amino acids in soybean meal. Breeding efforts may be limited by the inability of the plant to meet the crop N demand under conditions of high yield potential. Management practices can be an inexpensive and fast]response strategy to accurately match N supply with the crop N demand. However, there is insufficient research documenting the potential of these practices to influence protein quantity and quality. Past regional studies and meta]analyses stress the need of a more mechanistic understanding on the effect of cultural practices on grain protein. In addition, soybean producers adopt a diversity of new management practices that can largely influence N availability (i.e. soybean after fallow or after a cover crop). New tools that evaluate the crop N status can be used to adapt inputs to different crop N demands each year. We propose to evaluate different soybean maturity groups and cultivars across a wide range of environmental conditions (AR, KY, and MN) to: (1) quantify the potential of late season cultural practices (N fertilizer applications and B. japonicum inoculations) to improve protein quantity and quality (amino acid and fatty acid profiles), (2) evaluate these practices in systems more prone to N limitation (after winter cereal cover crop), and (3) to quantify if aerial images can be used to detect crop N limitations and adapt inputs. Finally, this study will generate a dataset that will be instrumental to improve and calibrate predictive tools that can explore a wider range of conditions and identify site]specific best management practices that maximize economic returns.