Why didn’t my cover crop work?

Kevin Elmy lists nine potential causes of things that could go wrong when you try growing cover crops on your farm

Cover crop growing after harvest.

Ever try something and it didn’t work the first time? What’s the next step? Try again doing the same thing, modify the approach or give up? Ideally, getting a mentor or someone with experience to find out what went wrong will help create a successful situation. Or maybe it just doesn’t work.

Cover cropping is no different. Adding diversity to a rotation can be intimidating and confusing. There are a lot of variable to consider. Most of them will be determined by climate, finances, goals and seed availability to name a few. So, what are the common reasons for cover crop failures?

1. Lack of goals
If you’re going on a road trip, you need to know where you’re going. Same thing for cover crops. Setting goals will help you determine what species to use. Using the wrong species will give results that do not match your goals. Hard pan remediation, grazing, hay, nitrogen fixation, increasing diversity, weed smothering, fall growth and reducing erosion are some examples of goals that can be met with cover crops.

2. Wrong timing
Species grow better when seeded at the time best for them. Seeding berseem clover or radish early into a cash crop will create harvest issues, as the berseem clover or radish will grow up into the cash crop. If you’re looking for nitrogen fixation, seeding legumes after July 15 will produce very little nitrogen. On the flip side, radish should be seeded later than August 1 for lowest level of management.

3. Wrong weather events

Farming success is dictated by the weather. In 2018, we broadcasted subterranean clover into our spring triticale. Then it did not rain until September. The clover germinated in June then died. When we seeded radish using a plane in 2015, we got a rain after and got a wonderful catch. Rains at the right time, if fall seeding — getting proper hardening off, and missing drought makes you look like a genius.

4. Wrong species selection
This is where many failures occur. Using the correct species makes many other mistakes disappear. If relay cropping, having a species that will either tolerate the cash crop competition, or is able to go dormant and come alive after the cash crop is removed is important. Grazing is another example. For grazing, species that will regrow and tolerate hoof traffic are important.

5. Identifying wrong causes
Like other troubleshooting issues, knowing the difference between the symptom versus the cause of the problem can create a different type of prescription. Is the low yield due to low organic matter, poor structure, salinity or hard pan? The causes can be related — salinity causes low infiltration, poor structure, hard pan and low organic matter.

6. Not enough patience
Sometimes the damage is so great it can’t be reversed by one treatment. Hard pan was created over years of abuse. Getting deep roots to penetrate the layer may take a couple of years. The same goes for salinity. Using different levels of salinity tolerance will act an indicator. As the soil is remediated, the less saline tolerant species start to show up.

7. Wrong seeding method
Matching seeding methods with seed is important. Broadcasting fababean and corn is going to give a low success rate. Seeding chicory the same depth as fababean is going to make the chicory fail. Chicory is a very small seed, so seeding deep is going to cause a high mortality in the seedlings.

8. A pest bridge
A pest bridge occurs when two crops are grown either together or in close succession. This increases hosts for shared insects, diseases and other ailments. An example is growing radish before canola. Not a good idea. These two crops share diseases, flea beetles eat both, and if all the radish do not germinate the year before canola, they can end up producing seed and being harvested with the canola. Fall rye before wheat is another example of a pest bridge.

9. Too much competition
When intercropping and cover cropping, space needs to be made for the extra plants. A quick rule of thumb is to aim for 120 per cent of the plants in total as compared to a monoculture. When the cash crop is decreased, more light gets through allowing the understory crops to establish.

These are a few common issues that can cause a wreck. Even experienced producers of cover crops and intercrops will have occasional hiccups. Having your homework done, knowing what you are trying to manage, what species, when to seed them, how to manage them, and watching weather patterns will allow execution of your plan.

Getting started

If setting goals is an issue and soil health is an overlying goal, start with the five key points of soil health: reduce tillage, reduce synthetic inputs, keep living roots in the soil, keep the soil covered, and include livestock on the land. Producers from Mississippi to LaCrete, Alta., have told me they cannot use cover crops for numerous reasons. But there are a significant number of growers around LaCrete growing cover crops successfully.

Every farm will be different due to different goals. Once cover crops are started on an operation more opportunities for cover crops will appear in different parts of the rotation, different soil types, different production risks and different climatic trends. And remember, diversity trumps density. Cover crops do not need to be as thick as the main cash crop. One to three plants per square foot may be adequate.

Cover cropping and intercropping are just more tools in the tool box. Using a welder and cutting torch as the main source of fixing is quick and efficient at the time, but the resale value of the equipment will deteriorate quickly. Using the right tool at the right time will improve the equipment, ensuring it runs as it should. Same for the soil. We need to start fixing our soils. Jay Fuhrer from the United States Department of Agriculture said if we take more carbon out of the soils than we put in, our children will not farm. If we put more carbon in than we take out, our children will be able to farm that land.

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