Oats as a Late Summer Forage Crop

Jason Hartschuh, Extension Agriculture and Natural Resources Educator, Crawford County; Al Gahler, Extension Agriculture and Natural Resources Educator, Sandusky County; and Dr. Bill Weiss, Professor and Extension Dairy Specialist, Department of Animal Sciences, The Ohio State University

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 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, we examined planting date, yield, forage quality and an application of foliar fungicide to control oats crown rust.

Usually the best scenario for growing oats for forage is to plant them into wheat stubble, which is normally available by mid-July at the latest.  However, The typical recommendation is to plant oats between August 1 and 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. Figure 1 shows how yield changed based on plating date and nitrogen rate. Similar to previous studies, applying 46 lb/acre of nitrogen significantly increased yield on all planting dates, but applying 92 lb/acre only increased yield during the late July planting. The July planting date did not receive rain for 8 days then received about 1.5 inches, possibly leading to a loss of nitrogen. Adding this study to others, the recommended nitrogen rate for summer oat forage is to apply 50 lb/acre 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.     

Figure 1. Oats yield based on planting date and nitrogen application (lb/acre).

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. Figures 2 and 3 show the crude protein (CP) and total digestible nutrients (TDN) over the 4 planting dates across 3 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 resulted in a difference between 46 and 92 lb/acre of nitrogen for both CP and TDN. The application of fungicide improved oats digestibility, increasing protein by 1 to 2% and TDN by 5 points. A consistent increase in energy concentration occurred 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 57% with a nitrogen application and 40% without the nitrogen application.  

Figures 2 and 3. Concentrations of crude protein and total digestible nutrients (TDN) in oats with different planting dates and nitrogen applications (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 lb/acre 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 lb, so a more accurate assessment for planting rate may be to seed 80 to 100 lb/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. Just 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 have emerged. When harvested as a stored forage, oats often need harvested as silage or baleage. If weather allows for dry harvest, the oats usually need tedded multiple times, and in late September or October, 6 or more days of drying may be required.   

Oats make an excellent double crop after wheat. When planted between mid-July and mid-August and fertilized with at least 46 lb/acre of nitrogen, average yields are in the range of 1 to 1.5 tons/acre of dry matter, and with ideal conditions, 3 or more tons/acre are very possible. The nutritional value of oats without fertilizer is about $250/ton of dry matter, and when fertilized, the value increases to about $280/ton. Oats make an excellent forage for dairy heifers, dry cows 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.