Oats: the unsung crop of summer seedings

Wednesday, August 1, 2012

Once portrayed as the last of the cultivated weeds, oats are making a comeback. But other crops, such as alfalfa and annual rye grass can also help you produce forage or build soil structure

by PAT LYNCH

If you want to reduce erosion, build soil structure and organic matter or produce forage for feed, consider summer seedings.

There is a long, extensive list of various crops which can do this, so I will concentrate on the main ones. These are oats, alfalfa and miscellaneous ones such as peas, tillage radish and rye grass.

To obtain successful summer seedings, you need moisture. Since moisture is generally limited in August and September, seedbed preparation for small seeded crops, such as forages, is critical. This past spring, there were many forage fields where seed was broadcast but, because of lack of rain, the stand did not catch. This system normally works since we always get rain in late May, but not this year. Typically, this broadcast seed was too shallow. There was not enough moisture to germinate the seed and keep it growing.

For summer seeding of alfalfa, the field must be level and you should work as shallowly as possible to conserve moisture. You can broadcast seed if you do it with diligence. If the seedbed is firm and seed is placed uniformly shallow, it will work. I have seen fields cultivated shallowly, rolled, broadcast seeded and rolled again. This placed the seed at the required quarter-inch depth. You would think a no-till drill would work well, but there have been too many poor experiences to make it widely used. Depth is critical. One notch too deep and the crop will not grow. If the field is uneven, it will be impossible to get uniform seeding depth.

You must control volunteer cereals when seeding alfalfa. You can do this by applying a graminicide after the crop emerges. This will also kill any grass seeded with alfalfa. If you have to kill the volunteer cereal, you can top-dress with grass seed next spring. You must have soil pH corrected and adequate levels of phosphorus and potassium.

The unsung crop of summer seedings is oats. Once portrayed as the last of the cultivated weeds by a former professor of mine, it is making a comeback. Interestingly, extension folks in the United States are recommending oats instead of rye for erosion control. The reason is that oats winter kills and rye does not. Too often, rye has problems with getting too big and drying the soil in the spring or attracting insects.

If you are growing oats as a cover crop to reduce erosion, just seed and go away. I like 40-50 pounds per acre of any oats. If you can find someone who cleans oats and has a supply of "bosom oats," this works well. These are the smaller oats that are cleaned out.

If you are growing oats for forage, apply at least 40 pounds of actual nitrogen. You should expect about one tonne per acre of high quality forage. If you get rain in September, you may be able to get a second cut in October. If you are shooting for a second cut, apply nitrogen again after the first cut.

There are some erroneous ideas about summer seeded crops. They will trap nitrogen. But research in Ontario has shown that this nitrogen is not available for next year's crops. Ontario research has indicated that there has been no yield difference between the "0" nitrogen plots and the cover crops. These crops will trap nitrogen, but then it disappears before next year's crop gets to it.

One of the little grown forage crops in Ontario is annual rye grass. You should expect higher yields from annual rye grass than from oats.

As for the other crops – peas, oilseed radish and tillage radish – these are interesting crops, but I am not convinced they add anything above what an oat crop gives. Oats are easier to grow. And if you plant oats, you can still use herbicides to control perennial weeds. BF

Consulting agronomist Pat Lynch, CCA (ON), formerly worked with the Ontario agriculture ministry and with Cargill.