Fall is the best time to gain the most benefits from manure applied to crop fields. Fall-applied manure insures that nutrients (especially nitrogen) will be readily available for crop growth in 1997. Keep in mind that many fields in the area are testing excessively high for phosphorus. In fact, the average soil test for phosphorus in Fond du Lac County is in the excessive range. To reverse this trend, crop producers need to make an effort to prioritize fields for manure applications based upon nitrogen need of the 1997 crop and soil test phosphorus levels. If soil test phosphorus levels are not known, fall is also the best time to soil test crop fields.
Calibration of the manure spreader is a key component to making the most efficient use of nutrients from manure and minimizing the likelihood for nitrogen leaching into groundwater.
To help determine actual manure application rates, the Fond du Lac County Land Conservation Department has purchased a pair of portable pad scales for "on farm" weighing of manure spreaders. If you're interested in having manure application rates determined for your farm, contact Mike Rankin at the UW Extension office. Sample bottles are also available to have manure tested for nutrient content.
Fall remains the best time to control quackgrass in sod fields that will be rotated to corn in 1997. Making glyphosate (Roundup Ultra) applications in the fall has several advantages over spring applications. Usually, fall applications result in better quackgrass control and significantly better corn yields the following year compared to spring applications. Quackgrass should be at least 6 to 8 inches tall and actively growing when treated. Reduced quackgrass control will occur if alfalfa plants are sufficiently tall to cover the grass vegetation. We generally only worry about temperatures affecting Roundup performance when they drop below freezing. However, quackgrass will have much more "active growth" if high temperatures are in the 60's and 70's as compared to the 40's and 50's. The absolute cut-off point for applying Roundup is considered to be 20 degrees F. At this temperature, a sufficient amount of leaf tissue will freeze and significantly reduce herbicide effectiveness. When lows reach between 20 and 30 degrees F, the best advice is to examine plants one to two days after the freeze for visible signs of injury. Finally, the rainfast period for Roundup is 6 hours. Time applications to avoid wash-off of the herbicide.
No significant yield decrease should be expected from an early frost to adapted soybean varieties (early Group II or I) if plants have reached the R7 growth stage (50% yellow leaves, pods yellowing, and one normal pod on the main stem having reached mature pod color). Beans on a frost damaged plant will mature even if they are green at least as early, if not earlier, than undamaged plants. Plants frosted between the R6 (pod containing a green seed the fills the pod cavity at one of the four uppermost nodes on the main stem with a fully developed leaf) and R7 growth stages may or may not suffer yield reductions depending upon variety maturity rating. Early maturing varieties suffered greater yield reductions at more advanced growth stages than later maturing varieties. In either case, the frosted green leaves will remain on the plant and make harvesting more difficult.
For producers that are planning to feed their soybeans, there may be some concern about the effects of frost on nutritional quality. The Wisconsin research indicates little impact on oil and protein concentrations when a killing frost occurs after the R6 growth stage. However, there may be serious reductions in quality for planting purposes because of low germination percent, seedling vigor, and a high susceptibility to disease.
Too much money and time is expended producing a crop to leave the finished product out in the field. An estimation of field losses can be done by determining the losses in terms of the average number of kernels lost per square foot and converting to a loss in terms of bushels per acre. The approximate number of kernels per square foot to equal one bushel per acre loss is as follows:
Corn: 2 kernels
Soybean: 4-5 kernels
The best approach to measure harvest loss is to construct a five to ten square foot frame and place it on the ground behind the combine. Count the number of kernels within the frame and divide by the number of square feet measured to determine average kernel loss per square foot.
Typical harvest losses should be no more than 2 to 3 bushels per acre for corn and 1 to 2 bushels per acre for soybean. Don't try to obtain zero loss because this will often result in an excess of broken kernels or split seeds. If losses are excessive, try to determine the cause.
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