Soil Health Minute: Cover crops after short-season cash crops
Using a cover crop following a short-season cash crop, like wheat or pea, is a great way to get on the fast track for achieving on-farm soil health building goals. There is a window of opportunity to get something growing and provide a different function to the soil than the cash crops in rotation.
In some areas, like the northern part of North Dakota, that window is tighter, so following the combine with a drill or dropping cover crop seed into a cash crop after the last herbicide spray and before harvest may help with establishment.
However, before even talking about cover crops and mixes, let's talk about residue management with wheat harvest. The most important step to this entire process is to have an even spread of residue out the back of the combine. If there are any residue issues, vertical tillage may be a tool that can help prep the field prior to seeding cover crops.
Now, let's dive into cover crops. Following a wheat crop, one of the most common reasons for using cover crops is moisture management. Wheat stops using water earlier in the growing season than other long-season crops and can have a dense residue mat holding excess moisture in the soil. This can be a tough step in the transition to no-till or reduced till.
Using late season moisture with a cover crop becomes important for preparing the field for next year's crop. Common cover crops used are radish, turnip, dwarf essex rapeseed, flax, pea and cereal rye. It is important to select species based on function, cost, comfort level and the next crop in rotation. To get the most out of the cover crop mix, spray out the first flush of volunteer wheat and weeds and then seed a cover crop (if time allows).
Following a pea crop (which are typically grown on sandier soils that are highly erosive), getting a cover crop established is critical for protecting the soil from wind erosion. Using a mix focused on fibrous roots from cool season grasses can stabilize the soil. In this case, oats, barley and low rates of cereal rye or winter wheat are great options.
Pick the cool season grass based on the next crop in rotation and soil conditions. For example, use oats before a wheat or corn crop. Use barley on soils that have salt issues. Cereal rye or winter wheat are good options if you want the cover crop to over winter and are going to soybean, but be cautious of too much moisture use on sandier soils the following spring.
These are just a few tips to get started with using cover crops after a short season crop. For more information, there is a booklet available on the NDSU Soil Health webpage called "Incorporating Cover Crops." This includes information from NDSU and also some farmer tips. You can also follow me on Twitter: @NDSUsoilhealth