Double-Crop Soybean: A Review.

Double-crop (DC) soybean (Glycine max L.) is cultivated in many regions of US. In most DC systems, soybean is planted immediately after wheat harvest, which increases potential profit where there would be fallow or a non-cash cover crop. However, there are many challenges discouraging farmers from planting DC soybean. The yield gap between full-season and DC soybeans is large, with the high-risk of crop failure due to heat and drought or freeze at the end of the season. To understand the real scenario of the yield gap between full season and double-crop soybean, a literature review was carried out with data from U.S. and around the world. The main goals of this study were to: i) improve understanding of the effect of the previous crop on DC soybean yields, and ii) quantify the yield gap between full-season and DC soybeans. The results compiled into this review presented that in a high wheat yielding environment, double-crop soybean yields are low. Also, full season soybean historically yields more than double-crop soybean.