A review of double‐crop soybean production in comparison to full‐season system in the United States

Abstract Soybean [ Glycine max (L.) Merr.] after winter wheat ( Triticum aestivum L.) is the most common double‐cropping system in the United States, driven by the desire for increased cash flow and profits and bolstering global food security. Despite its popularity, double‐cropping often results in a lower soybean yield compared to full‐season systems, attributed to various factors. Maintaining wheat stubble height ≤30 cm during harvesting and planting soybean in between wheat rows minimizes some negative effects of wheat residue. Planting double‐crop soybean immediately after wheat harvest is crucial, as late planting is the primary factor of diminished double‐crop yield. Late planting results in a shorter soybean growing season, limiting the time available to develop an optimal leaf area index (LAI). Harvesting wheat at high moisture or planting early‐maturing wheat cultivars with comparable yield potential can facilitate 7–10 days earlier soybean planting. Employing narrow rows (19 cm) during double‐crop soybean planting ensures rapid attainment of optimum LAI (3.5–4.0) by the pod set stage, maximizing solar radiation interception and canopy photosynthesis. A 16 kg ha −1 starter N may enhance early vegetative growth, expediting optimal LAI achievement. Indeterminate soybean may be more appropriate for double‐crop due to fewer branching habits, which reduces competition in narrow rows compared to determinate counterparts. Double‐crop soybean in narrow rows requires higher seeding rates than full‐season to maximize yield by optimizing LAI expeditiously. Additionally, double‐crop soybean is more vulnerable to drought and insect–pest infestation or defoliation than full‐season system. Therefore, managing double‐crop soybean with the same diligence as full‐season is imperative to maximize yield and profitability.