Kansas State University Mar 04, 2021 From edamame to cooking oil and tofu to livestock rations, soybeans are an important source of protein in food and feed around the world, and soybean production contributes a remarkable amount to the farm economy. For that reason, soybean breeders have worked for years to boost the yield potential from each plant. But Kansas State University and University of Minnesota researchers found in a checkoff-funded study that while yields have increased, important protein content of soybean seeds has slipped. “Yield improvement, which increased by 50%, led to a slight decline in protein concentration for soybean seeds,” said K-State Research and Extension agronomist Ignacio Ciampitti, “The selection for high-yielding genotypes has reduced seed protein concentration over time, but little is known about its impact on amino acids, which are the building blocks of protein.”