In North Carolina soybeans are often thought of as purely a rotational crop and not one that produces large profits. With over a million acres in the state, soybeans occupy 25% percent of the field crop acreage in N.C. Average yields in the state are about 35 bushels per acre, only 70% of the national average, however. Can the N.C. average begin to climb to the national average of 45 bushels per acre? What are some things any grower can do to increase yields?
In an effort to evaluate factors that may lead to yield increases, Dr. Jim Dunphy, Soybean Extension Specialist at North Carolina State University designed an experiment where he evaluated the effect of five different factors in a combined “Cadillac” treatment with funding from the North Carolina Soybean Producers Association and the soy checkoff. Each individual factor was then removed from the treatment one at a time to determine the effect of that factor in a high yielding system.
The “Cadillac” study was conducted at four different locations in 2015 and the high yielding “Cadillac” treatment included:
1) A high yielding variety (SS 5511N R2, 32RY55, USG 76S73R, or S76-R6)
2) A 15 in row spacing with 90,000 to 120,000 seeds/acre
3) A Poncho/Votivo seed treatment coupled with Optimize/BioForge
4) In-season applications of NH4SO4 (100 lbs N/A) at R2 and KNO3 (100 lbs N/A) at R5, and 5) fungicide applications of TopGuard at R2, Quadris Top 14-21 days after R2 and Priaxor at R5
While the study has only been conducted one year, preliminary results suggest some factors may lead to a yield bump that farmers should consider when making management decisions this season.
Variety selection is one of the most important management decisions a soybean producer can make. Selecting the right variety for the right environment is essential. In the “Cadillac” study, a 2.4 bu/A increase was observed when a high yielding variety was compared to an all-purpose variety. In addition to selecting a variety that matches the yield potential of a field, growers should also consider disease and pest resistance when choosing which varieties to plant. Choosing varieties with the proper resistance packages may help save money on pesticide applications later in the season.
While optimal row spacing varies by location, typically planting on narrower rows results in a yield increase. In the “Cadillac” study, a 6.9 bu/A increase was observed in treatments with 15 inch rows compared to 30 inch rows. Narrower rows allow quicker canopy closure and greater light interception. In addition to maximizing yield potential, narrower rows also help block light from reaching weeds and help minimize moisture loss.
Seed treatments can help protect yield potential by promoting germination and early plant vigor. In the “Cadillac” study, a 2.7 bu/A increase was observed in treatments with Poncho/VOTiVO compared to those without and a 1.2 bu/A increase was observed in treatments with Optimize/BioForge compared to those without. The Poncho/VOTiVO treatment has a biological coupled with an neonicitinoid insecticide. Optimize is an inoculant and BioForge is a 2-0-3 fertilizer. A number of other seed treatments are available that include fungicides, nematicides and insecticides. The selection of a given treatment should be based on issues specific to an operation. Neonicitinoid seed treatments should be used with caution to prevent resistance problems.
Proper soil fertility is critical to producing a high yielding crop. Soil testing to know what nutrients are needed prior to planting is a basic but important practice. When following soil test recommendations it is important to account for expected yields when determining what additional nutrients are needed. To grow 60 or 70 bu/A beans the crop may be fertilized for higher yields. Occasionally, in-season nutrient additions may be needed, but often the yield increase they provide does not cover the cost of the product. In the “Cadillac” treatment, the addition of foliar fertilizers only resulted in a 1.0 bu/A increase over treatments without in-season foliar fertilizer applications.
Foliar fungicides help protect crop yield, most often in cases where there is high potential for disease development (wet, humid environments). In the “Cadillac” treatment, the addition of a fungicide application at some point in the season lead to a 6.6 bu/A increase compared to treatments without fungicides. Determining the best time to apply fungicides is important to protecting the crop, but is difficult to do. Growth stage, weather, variety resistance and past disease development should all be considered when determining if and when to use fungicides.
As management decisions are made for the coming year, consider the five areas above to potentially increase yield. Incorporating even one or two of these practices into a management plan may provide a yield increase. As always, when deciding to incorporate an additional input, it is first important to consider potential return on investment.