With the decline of grain prices and the rising profit in livestock markets, there are more questions on using cover crops in both grain and livestock operations. What species to use? What seeding rates? Fertilizer requirements? When to seed? How to manage? How to terminate? Is there anything to “harvest”?
1. Setting a goal
The first question that needs to be answered is, “What’s the goal of the cover crop?” This will set up parameters for when to seed, what to seed and how to manage it. Is the cover crop to be used as a rotationally grazed feed stock versus stockpiled and grazed, greenfeed versus swath grazing, snow catch for winter cereals, salinity management, mid season crop loss, or another reason?
Once you’ve established the goal, you can select species. You know what grows locally. This is the base of most situations. Then add diversity. It is amazing to see how the blends have more vigourous growth than monocultures. A monoculture has the same plants growing and has the same roots pushing through the soil at the same rate in the same soil volume competing for the same nutrients and water at the same time. With a well-planned cover crop blend, roots will be growing in all directions, at all times reducing the stress on the crop.
Then you run into areas where nothing, or very little grows. A soil test may be needed to find out what you are dealing with. Or, if you suspect that salinity, for example, is the issue, then select more saline tolerant plants. If there are other issues like weed issues, soil compaction, nutrient loss or erosion concerns, there are a different set of appropriate species. Some of the same species may be grown, maybe at different rates.
2. Choosing a species
Two factors to look at while picking species are cost and efficiency. Effectiveness is hard to measure quantitatively, especially when dealing with specific issues or soil health. Cost is also relative. It’s also hard to value the benefits of improving future crops, salvaging soil or crops, or transitioning crops in a timely way.
The main species we have been using on are farm are proso millet (Crown or red), crimson clover, forage brassica, sunflowers, Phacelia, oat, winter triticale, sorghum Sudan grass, annual ryegrass, tillage radish and conventional Canamaize corn. Buckwheat is on the list of species that we will use more in the future. We can use hairy vetch, but it can have high hard seed counts, which means it may volunteer two to three years after seeding. Plus, it is naturally resistant to glyphosate so it should be managed more carefully in blends.
We have used a couple of different blends on our farm depending on our goals. We have used a proso millet, crimson clover, tillage radish blend as a green feed crop, that we then seed winter triticale into.
- Click here for a cover crop species summary (depending on your browser, you may need to increase size of image when the new window opens)
3. Getting it in the ground
This past year with all of the June rains, anything that was not seeded in May had to wait until mid to late July to get seeded. We assumed we would not be able to get a green feed crop off of those acres, so our seeding rate was reduced somewhat and we added sunflowers to the mix.
By the end of August, there was decent top growth of the mix and seeding Luoma winter Triticale into it was not an issue, yet had good snow catch potential. The other “blend” seeded was straight tillage radish. Our goal was to dry some land out, recapture any nutrients that were leached out, and to evaluate tillage radish’s competitiveness against foxtail barley.
Water stopped flowing across these fields in mid July. We seeded tillage radish the first week of August. By September 5, the radish plants covered the ground, their roots were drilled down about 24 inches, and the soil was firm enough to drive across. Next spring we’ll examine soil tests and foxtail barley.
The biggest problem producers have with tillage radish is seeding too early. Ideally, you can manage the tops by clipping, mowing, grazing, haying, oar a frost three to six weeks after emergence. Seeding in May, June or early July will give the plant enough time to bolt. In Southern Alberta or Manitoba under a normal year, whatever that is, they can be seeded into September. It is not the first frost we are looking at — it is the killing frost.
If they’re seeded earlier, some means of top growth control is required. The results of the radish growth can be seen with a shovel. The fine taproot will drill down about one inch per day. Tuber production occurs in late August and early September, when the plant gives up trying to produce seed and attempts to be a winter annual, producing a nutrient storage vessel. After three nights of -9 C, the plant dies. If it is just basal leaves, by middle of April, there will be very little tillage residue left.
The rest of the variables will be left up to the producer and the year. Successful results, like the rest of what producers do in agriculture, are going to be dependent on the goals we set.
Cover crops are not a silver bullet to fix all problems. It’s just one tool in a toolbox. A hammer is a good tool, but to tighten a nut on a bolt, a wrench may be a better choice. Given a thought-out plan and defined goals, cover crops can save time, money, improve nutrient distribution in the soil, improve soil physical characteristics, provide forage and prevent erosion. These will improve future economics and sustainability.