Researchers strive to refine double-crop systems for top-profit production. Year- round land use allows soil protection during winter months, recapture of some previous crop-use nutrients, improved cash flow, added market opportunities, improved use of labor and equipment, and more.
Drs. S. Kyei-Boahen and L. Zhang of Mississippi State University analyzed the yield and economic returns of full-season soybeans compared with wheat double-cropped with early-maturing soybeans and reported their findings.¹
They found that maturity group IV following wheat yielded more than group III or V. Soybean yields for the three early-season groups ranged from 30.6 to 56 bushels per acre (bu/A). Full-season soybeans out-yielded double-crop beans by 10 to 40 percent. However, wheat averaged 77 bu/A over the three-year period and contributed more than 60 percent of the double-crop profitability. They concluded that groups III and IV soybeans double-cropped with wheat were more profitable than full-season soybeans as a single crop. Group V soybeans planted after wheat weren’t harvested in two of the three years due to late maturity.
The data identifies two key practices needed for top profitability: selecting the maturity group(s) that allows early, consistent harvest; and planting immediately following wheat harvest.
Other research studies identify additional best management practices for improving yield and profitability of soybeans double-cropped with wheat.
• Select high-yield, high-quality wheat varieties and plant within the recommended time period. This allows early canopy closure as well as optimum root and tiller development.
• Soil-test fields and apply limestone to meet soybean needs and fertilizer as needed for the double-crop system.
• Fertilize the wheat crop for both wheat and soybeans. Wheat benefits in years of ideal production conditions. Residual wheat nutrients and soybean fertilizer is in place for earliest-possible planting of soybeans.
• Wheat straw continues to increase in value as a harvested crop. Sale for mulch, animal bedding, roadside erosion control, or as a source of fiber can provide extra dollars of income per acre.
• Total nutrient uptake by a wheat-soybean double-crop system must be available from the soil and applied fertilizer if top yields are to be gained.
¹Agron. J. 98:295-301 (2006).
* Soybeans derive most of their N from symbiotic N fixation.
Source: Drs. S. Kyei-Boahen and L. Zhang of Mississippi State University