August 15 to September 7, 2013
This report is intended to provide farmers with crop and weather information to help in making cropping decisions. This is the final report for the season.
Weather: For late August and early September, rainfall across the Jersey Valley Watershed, south of Cashton, WI, has been virtually zero. It has rained approximately 1 inch since August 1; distributed as ¼ inch on the 8-5, ½ inch on the 8-11, and ¼ inch on 8-22. Soil moisture content entering this fall is as dry as September 2012.
The Wisconsin Crop Progress report (09-09-13) shows the west central Wisconsin / La Crosse region to have 66% of corn with dough stage kernels and 30% of corn dented; 13% of soybeans have leaves that are turning. Crop development, maturity and harvest decisions are mostly being governed by plant moisture stress at this time. The average date for a killing frost in La Crosse is September 29th. As of September 8, 2013, La Crosse had accumulated 2571 growing degree days (base 50) which is slightly above normal.
Alfalfa: Harvest of third crop alfalfa is mostly complete. Avoid harvesting stands intended for production next year until after night time temperatures are consistently in the lower 20’s (usually mid-October). Topdress potash on fields with soil test levels below 150 ppm. Alfalfa needs large amounts of potassium in the fall to replenish nutrients used during the growing season and to prepare the crown for cold, winter soil temperatures.
Corn: Corn maturity ranges from the R3 to R5 stage (dent). At the R5 stage, the kernels form a “dent” on the exposed side of the kernel as moisture levels decrease. Plants still need 2 weeks for the milk line to move halfway down the kernel. After this stage, grain yield losses from an early frost or continued drought stress will be minimal. Kernel moisture will drop from 55% at early dent to 30% at maturity (black layer). Whole plant moisture will decrease from 75% to 55 % during this same time frame. Corn silage harvest will begin soon. Regionally, some corn fields are being harvested as silage due to drought stress. Watch whole plant moisture levels, as they will drop quickly with the combination of shorter fall days and drought stress.
Soybeans: Soybean maturity ranges from the R4 to R6 stage (full seed). At the R6 stage, green seeds fill the pod cavity at upper nodes on the main stem. At R7 stage leaves and pods begin losing their green color and move toward maturity. It takes roughly 10 days for plants to advance one stage (e.g. R6 to R7). Plants attaining the R7 stage will have minimal yield losses from an early frost.
Pasture: Pastures are very dry. Available forage material is very dependent on animal stocking density and paddock grazing duration. Some managed pastures have 6-8” of very dry stockpiled material; other pastures with full time animals present are dried brown and eaten short.
Small Grain Cover Crops: The best time to plant winter wheat or winter rye is during September. To minimize cost and soil disturbance, seed with a no-till drill or surface broadcast the grain and then topdress with liquid manure (6000 gallons / acre).
Manure on Warm Soil: If applying fall manure after corn silage, consider waiting until soil temperatures drop below 50° F to minimize the conversion of ammonium and organic nitrogen to nitrate nitrogen. A significant amount of that nitrogen could disappear before next crop season as nitrate nitrogen is subject to leaching. During warmer falls, soil temperature can remain above 50° F through most of October. If it is necessary to fall apply manure before soils cool below 50° F, use a nitrification inhibitor to reduce nitrogen loss.
Slow down and be safe during this fall harvest season.
Kevan Klingberg – Certified Agronomist (715) 983-2240 firstname.lastname@example.org