Rotate Crops to Increase Efficiency
Published: Friday, April 5, 2019
The following is from Michael Staton, Michigan State University Extension educator.
Soybean market prices for the 2019-20 marketing year are projected to be near or below the breakeven price when land costs are included. Because of this, soybean producers will need to increase efficiencies and reduce production costs in 2019. The follow-ing is a list of recommendations from Michigan State University Extension for reducing soybean production costs with-out significantly affecting yields.
Planting soybeans after soybeans will reduce your yield potential by 5 per-cent after the first year. Yield reductions can exceed 10 percent the third year soybeans are planted in the same field. In addition, long-term pests such as soybean cyst nematodes and white mold are more likely to increase when soy-beans are planted after soybeans.
Tillage trials conducted across the U.S. and in Ontario have shown that till-age does not significantly affect soybean yield. In some cases, no-till yields were higher than tilled yields. If your fields are relatively smooth and free from harvest ruts and your planting equipment is equipped to plant through the exist-ing residue, consider planting without additional tillage. Tillage operations may be necessary to repair harvest ruts prior to planting and may be beneficial when planting very early (last week of April).
Variety selection is always your most important decision when planting soybeans. By choosing varieties carefully, you can increase your yield potential by 5 to 12 bushels per acre and reduce yield losses due to white mold, sudden death syndrome, Phytophthora root and stem rot and soybean cyst nematodes without any additional cost. The final step is to strategically match the vari-eties you selected with the pest pressure and productivity of your specific fields.
Numerous planting date comparisons have shown that the optimum time to plant soybeans is the first week of May. Yield losses of .3 to .6 bushels per acre have been documented for each day that planting is delayed after May 8. However, it is far better to delay planting than to plant into soil that is too wet.
In general, most agronomists agree that 100,000 uniformly spaced plants at harvest will produce the maximum economic return under most conditions. However, data collected from 40 replicated on-farm trials conducted in Michigan from 2015 to 2018 show that thin soybean stands can produce surprisingly high yields. In fact, the 100,000-seeds-per-acre planting rate was more profitable than the 130,000 and 160,000 planting rates when all 40 sites were combined and analyzed. Higher planting rates are recommended when planting into marginal soils and when planting late as these conditions limit soybean growth. Higher rates are also rec-ommended in northern Michigan, where early maturing varieties are planted. Under good conditions, planting rates should be 15 to 20 percent higher than your intended harvest populations.
Soybeans will generally perform well at soil pH levels between 6 and 7. However, the optimal range is between 6.3 and 6.5 as this range maximizes nu-trient availability and biological nitrogen fixation while minimizing soybean cyst nematode population growth. Variable rate lime applications are highly recommended to achieve more uniform soil pH levels within fields.
Hundreds of university trials have shown that nitrogen fertilizer applications to soybeans are rarely profitable. This has been con-firmed in replicated on-farm trials conducted in Michigan.
Foliar fertilizer applications to soybeans are rarely profitable. This has been demonstrated in hundreds of university trials conducted across the U.S. and the Michigan SMaRT foliar fertilizer trials where only eight of the 117 replicated on-farm foliar fertilizer trials were profitable. The exception is foliar applications of manganese fertilizers, which are recommended to correct visible manganese defi-ciency symptoms.
The critical level for a given nutrient is the soil test level at which 95 to 97 percent of the crop's yield potential will be reached with no additional inputs of the nutrient. The critical level for P is 15 parts per million and the maintenance range for soybeans is 15 ppm, so P soil test levels should be maintained between 15 and 30 ppm.
The critical K level is calculated by multiplying the cation exchange capacity by 2.5 and adding 75. For example, the critical K level for a soil having a CEC of 12 meq/100g is 105 ppm [(12 x 2.5) + 75]. The maintenance range for soybeans is 30 ppm, so the K soil test level for this soil should be maintained between 105 ppm and 135 ppm.
Soybean seed treatments including fungicides, insecticides, inoculants and nematicides have produced inconsistent yield benefits in university trials. For example, seed treatments containing multiple fungicides and an in-secticide were profitable in only five out of 21 replicated on-farm trials conducted in Michigan in 2017 and 2018. Seed treatments may be warranted when pest problems such as sudden death syndrome, or Phytophthora root rot have been verified or when planting conditions favor pest damage. Examples of planting conditions that increase the po-tential for pest damage include: early planting (Pythium and sudden death syndrome); planting into grass sods (white grubs and wireworms); and when manure or green plant material has been incorporated within two weeks of planting (seed corn maggot).
Prophylactic foliar fungicide applications have produced modest yield increases in Michi-gan on-farm research trials. Stratego YLD was evaluated in nine trials in 2012 and 2013, producing an average yield in-crease of 1.4 bushels per acre. Priaxor increased yields by 2.1 bushels per acre when averaged across 22 trials conduct-ed in 2014 and 2015. These yield increases are not sufficient to cover product and application costs given the projected market prices.
However, foliar fungicides can be an important tool for managing white mold as they have been shown to reduce disease incidence by 0 to 80 percent in university trials. Using a combination of tactics is rec-ommended when planting soybeans into fields having a history of white mold. These include wide rows, resistant va-rieties, reduced planting rates, irrigation water management, careful tillage decisions and foliar fungicides.
The MSU Weed Science Program evaluates commercially available weed control programs each year. The most profitable weed control programs year-in and year-out provide the highest level of weed control and minimize crop injury. The cost of the weed control programs is also considered, but this does not affect overall profitability as much as the level of weed control and crop injury.
Reducing production costs and improving efficiency will help soybean pro-ducers respond to the projected market prices.
This article was produced by the SMaRT project (Soybean Management and Research Technology). The SMaRT project was developed to help Michigan producers increase soy-bean yields and farm profitability. The SMaRT project is a partnership between MSU Extension and the Michigan Soy-bean Promotion Committee.
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