Soybean average yields can be better, according to Fred Below, University of Illinois crop physiologist. He has been evaluating "Six Secrets of Soybean Success" and believes the national average soybean yield can climb to as high as 85 bushels per acre. Here is his ranking of influences on soybean yield.
1. Weather. Farmers have no control, but it does affect yield. Below says farmers can mitigate any negative effects with healthy soils and early-season protection. Strong roots help relieve environmental stresses, while early planting can promote vegetative growth and node formation.
2. Soil fertility. Soybean nodules work to provide nitrogen (N), but it's not enough in a high-management system. At high yields, soybeans use more N than they can fix. The rest has to come from the soil or added fertilizer. Below's studies show applying fertilizer containing N, phosphorus (P), zinc and sulfur immediately prior to planting adds almost 4 bushels per acre.
3. Genetics and varieties. Seed selection matters. Results from the University of Illinois Variety Testing program show a 20-bushel yield swing between soybean varieties of similar maturity.
4. Fungicides. Foliar fungicides and insecticides at the R3 growth stage add an average 3 bpa. The leaves at specific, given nodes supply most of the energy to produce pods and beans. More than half the soybean yield comes from middle nodes, so protecting photosynthetic capability of the middle leaves is critical. One more pod per plant can add 2 bushels in yield.
5. Seed treatments. Fungicidal, insecticidal and nematicidal seed treatments protect yield potential by promoting germination and seedling establishment resulting in 5,000 to 10,000 more plants per acre. The treatments also promote early plant vigor for an average 2-bpa benefit.
6. Row spacing. The advantage of narrow rows varies by year, but Below found a 2- to 5-bushel yield advantage for 20-inch rows versus 30-inch rows. The configuration can also be used in corn. For soybeans, 20-inch rows are the compromise between quicker canopy closure and greater light interception, Below said. That spacing also allows for more canopy air movement than 15-inch rows.
The United Soybean Board has set the ambitious goal of reaching a 60-bushel-per-acre national average by 2025. Many U.S. soybean growers have already surpassed that milestone and set their sights on reaching 100-bushel yields. In this seven-part series, DTN/The Progressive Farmer looks at some of these top producers and their practices. This is the second story in the series.
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