Early High Moisture Wheat Harvest Improves Wheat and Double-Crop Soybean Yield and Quality.

Double-cropping may increase profit, spread out cash flow, ensure global food security by increasing food production, and provide environmental benefits via continuous land cover. Soybean [Glycine max (L.) Merr.] following winter wheat (Triticum aestivum L.) is the most prevalent double-cropping system in the United States. However, soybean yields less in double-cropping than full-season production systems due to delayed planting. Harvesting wheat at high moisture (e.g., 20%) may allow 7 to 10 d early soybean planting without affecting wheat yield and quality. We evaluated the effect of early high moisture wheat harvest on wheat and double-crop soybean yield and quality across five Mid-Atlantic states including Pennsylvania, Maryland, Delaware, Virginia, and North Carolina in 2015 and 2016. At each location, we harvested wheat five times at 4 to 7 d intervals beginning when grain moisture approached 20% and immediately planted six soybean cultivars of three relative maturities. Wheat grain moisture tended to decrease with time, depending on weather. Wheat harvesting dates explained 77% of the variation of wheat relative yield, which decreased quadratically with delaying harvesting. Wheat test weight decreased linearly and falling number decreased curvilinearly with delayed harvesting. Double-crop soybean yield decreased quadratically as planting was delayed from early June to late July. Cultivar yield differences were more dependent on environment than relative maturity. Normalized difference vegetation index (NDVI) usually peaked at the R4 stage with the maximum value of 0.85. At the R6 stage, NDVI was strongly correlated with soybean yield and explained 67% of the variation of soybean yield. Results suggest that harvesting wheat at high moisture can increase wheat yield by reducing test weight loss as well as double-crop soybean yield by allowing early planting; hence, increase overall double-crop enterprise income.