Richard Leitz

Sustainable Agriculture and Soybean Breeding: Contribution of Soybean Yield Increase to Sustainable Agriculture

Soybean production has increased steadily in the USA since the beginning of twentieth century due to increases in yield (23.4 kg ha−1 year−1) and total area for soybean production (0.41 million ha year−1). This chapter discusses factors that influenced the increase in soybean production and its association with yield as an important contributor to sustainable agriculture. Four distinct eras for soybean production have been identified. The first era (prior to 1942) was characterized by adaptation of soybean land races introduced to the USA. The second era (1943–1977) was defined by cultivars that resulted from public breeding programs, followed by predominantly private sector breeding effort during the third era (1978–1998). The fourth era (1999–now) is defined by introduction of biotechnology traits. Yield increase was observed throughout this 87-year period, with the greatest rate of increase (31.8 kg ha−1 year−1) associated with the biotechnology trait era. Soybean yield improvements were generally due to breeding effort, optimization of agronomic practices, increased investment in research, and advances in biotechnology. Farmland used for soybean production increased during the first two eras, showed fluctuations during the third era, and stayed generally flat for the fourth era. Greater yield allowed for less farmland required for soybean production. It has been estimated that if US farmers were to grow low yielding soybean cultivars from 1924, they would need to plant almost four times as many hectares to achieve 2010 soybean production. In that respect, the continual effort of modern agriculture towards increasing soybean yield is one of the most important contributors to sustainable agriculture.