May 19, 2020
Oats is traditionally planted as the first crop in early April as a grain crop or an early-season forage. One of the beauties of oats is its versatility in planting date. Oats can also be planted in the summer as an early-fall forage for harvest or grazing.
Summer oats has a wide planting window but performs much better with an application of nitrogen, and it may benefit from a fungicide application to improve quality. During the summer of 2019, we conducted a study to examine the planting of oats from July 15 through early September to examine tonnage and forage quality. Through this trial, planting date, yield, forage quality and an application of foliar fungicide to control oats crown rust was examined.
Usually the best scenario for growing oats for forage is to plant it into wheat stubble, which is normally available by mid-July at the latest. However, the typical recommendation is to plant oats between Aug. 1 and Aug. 10 to maximize tonnage and quality, since the shorter day length triggers oats to grow more leaf instead of producing seed; but if planted too late in the year, there is not enough time for growth. The oats in this study were harvested between 60 and 75 days after planting, with full head emergence.
How plant date, N affect yield
Figure 1 shows how yield changed based on planting date and nitrogen rate. Similar to previous studies, applying 46 pounds of nitrogen significantly increased yield on all planting dates, but applying 92 pounds only increased yield during the late-July planting. The July planting date did not receive rain for eight days, and then it received about 1.5 inches, possibly leading to a loss of nitrogen.
Adding this study to others, the recommended nitrogen rate for summer oats forage is to apply 50 pounds of nitrogen at planting. When planted in early September, yields fall to an average of a half-ton per acre, making it less economical to mechanically harvest as stored forage and more economical to graze.
N affects feed value as well
Not only does nitrogen rate affect yield, but also the feed value of the oats. In 2019, the oats were severely infected with crown rust. Fungicide was sprayed on the plots based on recommendations in the 29th issue of the 2019 C.O.R.N. newsletter. The fungicide application significantly reduced the presence of rust. Without a fungicide application, over 50% of the leaf was coved by rust, while the fungicide application prevented the severe outbreak and decreased the rust content to less than 1% coverage, on average.
Figure 2 and 3 show the crude protein (CP) and total digestible nutrients (TDN) over the four planting dates across three rates of nitrogen, with and without fungicide. Fungicide application had no effect on yield but did affect forage quality. The application of nitrogen increased forage quality, but only the mid-August planting saw a difference between 46 and 92 pounds of nitrogen for both CP and TDN.
The application of fungicide improved oats digestibility, increasing protein by 1% to 2%, and energy by 5 points. Energy also saw a consistent increase over all treatments based on planting date. Crude protein averaged around 14% when nitrogen was applied, but only 10% without nitrogen. TDN had an average of 50 with a nitrogen application, and 40 without the nitrogen application.
For figures 2 and 3, T = fungicide treatment; U = no fungicide treatment
Based on previous trials, we recommend seeding oats at 2 to 3 bushels per acre and applying 50 pounds of nitrogen at planting. With most seed oats or triple-cleaned feed oats commonly used for fall forage, test weight is normally much higher than the standard 32 pounds. This means a more accurate assessment for planting rate may be to seed 80 to 100 pounds per acre, regardless of the source.
The oats should be planted into moisture up to 1.5 inches deep, if needed. No-till planting is the ideal seeding method, but shallow conventional tillage may be required to incorporate nitrogen, assist with weed control, and improve seed to soil contact if drills are not closing the seed slot.
Keep in mind that if mechanical harvest is the intention, loose soils from conventional tillage may contribute to significant soil in the harvested crop, leading to higher ash content in the feed. If weeds are present, a chemical application of glyphosate plus 2,4-D can be used to clean fields up before planting or before oats has emerged. When harvested as a stored forage, oats often needs to be harvested as silage or baleage. If weather allows for dry harvest, the oats usually needs to be tedded multiple times; in late September or October, six or more days of drying may be required.
Oats makes an excellent double crop after wheat. When planted between mid-July and mid-August and fertilized with at least 46 pounds of nitrogen, average yields are in the range of 1 to 1.5 tons dry matter, and with ideal conditions, 3 or more tons is very possible. The nutritional value of oats without fertilizer is about $250 per ton of dry matter; when fertilized, the value increases to about $280 per ton.
Oats makes an excellent forage for sheep, goats, beef cows, feeder calves, dairy heifers — and when made early, even milking cows. Planting after wheat harvest provides forage and increases farm profitability, with return on investment rivaling and often surpassing the potential for double-crop soybeans.
Hartschuh and Gahler are agriculture and natural resources Extension educators in Crawford and Sandusky counties, respectively, and members of the OSU Extension Beef Team. The Beef Team publishes the weekly Ohio BEEF Cattle letter; find it at beef.osu.edu.
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