Spring checklist for improving soybean yields

Implementing good soybean management practices this spring will increase the potential for harvesting higher yielding soybeans.

Soybean yields are largely determined by the weather occurring during the growing season. However, implementing good management practices can help the crop be more tolerant of poor growing conditions and take full advantage of good conditions. In both scenarios, good management improves soybean yields. This article contains a summary of spring management practices for improving soybean yields.

Inspect, repair and calibrate planting equipment

Uniform seed emergence will improve yields so inspecting and repairing planting equipment is critical. Small seed will plant more evenly and will experience less mechanical damage than large seed when planted with a drill equipped with a fluted metering system. Always calibrate your planting equipment by seeds per foot of row or seeds per acre. Recalibrate whenever seed size changes. For more information on calibrating soybean drills, read MSU Extension News article “Calibrating soybean drills.”

Control weeds prior to planting

Always plant into weed-free fields. Delayed burn-down applications have resulted in yield losses of eight bushels per acre in MSU research trials. Controlling weeds at least two weeks prior to soybean emergence will also significantly reduce black cutworm damage. Tillage and herbicides can be used to control weeds.

Table 1. Effect of delayed burndown on soybean yields averaged over six sites

 Application time

Yield (bushels/acre)

 7 days prior to planting

56.7

 VC to V2 soybean

48.4

 V3 to V5 soybean

47.5

 Untreated

36.6

Source: Christy Sprague, Michigan State University

Broadcast potassium fertilizer on coarse-textured or organic soils if needed

Spring applications of potassium fertilizers are recommended on coarse-textured soils having CECs less than 6 mEq/100 g or on organic soils due to a higher potential for leaching losses to occur on these soil types.

Apply phosphate fertilizers if recommended

MSU recommends applying maintenance levels of phosphorus(0.8 lbs. of actual P2O5 per bushel) when phosphorus soil test levels are between 15 and 30 ppm. No phosphorus is recommended when soil test levels exceed 40 ppm.

Handle soybean seed carefully

Soybean seed is very fragile. Germination rates and seed vigor can be significantly reduced when bulk seed is transported through augers and conveyors or dropped from heights greater than 10 feet. Keep augers full and run them slowly to reduce seed damage. For additional information, read MSU Extension News article “Handle soybean seed carefully.”

Plant into good soil conditions

Adequate and uniform soil moisture, soil temperatures higher than 50°F and a level surface will promote uniform seedling germination and emergence.

Plant soybeans early

On average, the first two weeks of May is considered the ideal planting window for soybeans in the lower half of the Lower Peninsula. Yield losses of0.4 of a bushel per acre per day when planting is delayed past May 8 have been documented by researchers at the University of Wisconsin. If you plan to plant before May 1, read MSU Extension News article “Understanding and reducing the risks associated with early-planed soybeans.”

Inoculate seed whenever soybeans are planted

Researchers from Michigan State University and the Ohio State University report average yield increases of 1.3bushels per acre from using inoculants on fields having a history of soybean production.

Consider a soil-applied residual herbicide application followed by a post-emergence application

Benefits include reduced early-season weed competition, consistent control of weeds that emerge over a long time period, consistent control of hard-to-control weeds and delay the development of herbicide resistance.

Plant at the optimum seeding rates

Assuming a warm germination test of 90 percent or more, MSU recommends planting 175,000 seeds in 7.5-inch rows, 150,000 seeds per acre in 15-inch rows and 130,000 seeds per acre in 30-inch rows.

Plant in narrow rows

University research trials have shown that planting in narrow rows significantly increases soybean yields. The narrow row advantage is greater in no-till.

Plant at the optimum depth

Plant beans between 3/4 and 1.25 inches deep. In general, plant at the shallower end of the range when planting early and in no-till and plant at the deeper end of the range later in the season.

Plant a range of maturity groups

Planting a range of soybean maturity groups spreads your risk during the growing season, allows more of the crop to be harvested at the optimum stage and allows for timely wheat planting. The maturity groups planted should be adapted to the area and the range of maturity groups planted should be from one half to one full maturity group.

Use seed treatments where warranted and provide uniform coverage of the seed

Fungicide seed treatments are warranted when planting early or where pythium is known to be a problem. The fungicide selected should provide excellent control of pythium. Insecticide seed treatments are warranted when seed corn maggot, wire worm or bean leaf beetle damage is expected.

Monitor fields closely beginning at emergence

Diagnose emergence problems early. Emergence can take six to 14 days depending on soil temperature and soil moisture conditions. If slow and uneven emergence occurs, dig up the delayed plants and look for disease or insect damage. Plant stands of 100,000 plants per acre will produce optimum yields if the plants are relatively evenly spaced. After emergence, continue checking fields for bean leaf beetles and black cutworms. Monitor weed heights and use this information to time post-emergence herbicide applications.

This article was produced by the SMaRT project (Soybean Management and Research Technology). TheSMaRT project was developed to help Michigan producers increase soybean yields and farm profitability. The SMaRT project is a partnership between MSU Extension and the Michigan Soybean Checkoff program.

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