Last September we seeded our first round of cover crops on roughly 200 acres. These crops that we will never harvest are probably the most exciting thing on the farm right now for me.
What is a Cover Crop
A cover crop does just what it says. It covers the soil during the period between the time you harvest one crop and plant the next. For my farm this means winter. Our cover was seeded by airplane in mid September just ahead of harvest. We chose aerial application in order to give the seeds a chance to start growing before harvest and before winter set in. Next year I think we need to be seeding in early September to see more growth ahead of cold temperatures. Flying seed on requires more seed to account for seeds that won’t germinate as well compared to using a drill or planter to place the seed in the soil, but a plane allows you to get started growing before harvest.
Cover crops provide erosion control, improve soil structure, increase organic matter, scavenge soil nutrients, suppress weeds and pests, and some can be used as forage for livestock. But not all cover crops accomplish all these goals. Each one has its own unique qualities and must be managed differently. Many of them work even better when they are planted together on the same ground.
My Cover Crops
For now I’m just going to talk about the cover crops we have on our farm right now. First we have annual ryegrass. Ryegrass can develop very deep roots quickly. I attended a cover crop field day and saw ryegrass roots less than two months old that were already over 3′ deep in the soil profile. That’s amazing. Those roots are pulling up nutrients and when the grass dies those root channels will improve water infiltration and leave paths for next year’s crop roots to follow. Beneficial organisms like earthworms will follow those paths as well. All this while building soil organic matter and structure.
Getting rid of annual ryegrass is probably the most important part of management. The grass needs to be sprayed in the spring when it is actively growing. That means you have to wait until temperatures begin to warm up. If the grass isn’t growing it won’t take up any herbicide. If spring is warm and wet ryegrass can get tricky. Wet means you can’t get out in the field to spray giving the ryegrass time to grow even more and become tough to kill. I don’t foresee this being a huge problem, but important to know about ahead of time.
Adjacent to the ryegrass we are growing winter cereal rye. Cereal rye may not grow as thick or have as much of a root system as ryegrass, but it has some great qualities of its own. Allelopathy is one of those qualities. Cereal rye has the natural ability to suppress weeds. I also learned during the field day that cereal rye may have an effect on soybean cyst nematodes as well. The agronomist on hand all but guaranteed a 4-5 bushel bump in soybean yield if you have nematode problem. Lower pesticide use makes everyone happy right? Unlike ryegrass, you can plant into a growing rye cover crop and kill off the rye after planting. If we go that route, I’ll have some pretty neat pictures of the planter rolling through a green field of fairly tall rye. That’ll be kinda weird. It may be taken care of with the grass though since they are in the same field.
Finally we have about 120 acres of a mixed cover growing in one field. Oats and radishes growing together. These two crops will winterkill when the temperature stays around 20 for a few days. Ours have already died off in the last two weeks.
Radishes are really cool because they send a big tap root deep into the soil along with fine-haired roots. They are great at soaking up nutrients that may otherwise be lost to the atmosphere or through groundwater. When spring comes and the radishes start to decay they will slowly release those nutrients to the corn we will have planted by then. I should note these aren’t the radishes you are used to eating. These are called tillage or groundhog radishes. They are white and look somewhat like large carrots.
Oats are great because they scavenge nitrogen. Nitrogen is very important to a corn crop. Oats develop deep roots to improve soil structure much like ryegrass. I hope our oats/radish mix really show some results in next year’s corn.
What excites me most about cover crops is keeping more of what we have and potentially using less inputs in the future. I feel that increasing organic matter alone will be a great improvement to our farm even without all the other benefits. As organic matter increases soils can handle water better and hold on to and provide more nutrients to a growing cash crop. Improved soil structure means our crops will grow deeper roots. Having an active root system in the ground twelve months of the year instead of six means the beneficial organisms in the soil will be more active which is really good.
Nitrogen is one of our most expensive and most necessary inputs. If cover crops can allow us to either use less nitrogen or at least do a better job of effectively using the nitrogen we apply that will be a huge bonus for corn. Boosting yields on one end and cutting costs on the other end is a pretty great combination. Cover crops aren’t free, but I think their benefits will far exceed the costs.
Cover crops can also break up soil compaction. Compaction caused by driving heavy equipment over soil limits water infiltration and root growth. This is a reason no till and cover crops go so well together. In a true no till situation you won’t be doing any deep tillage to deal with compaction, and cover crops give you a way to deal with that.
When spring comes around you’ll definitely being seeing more about our cover crops. I’m sure we’ll be seeding more this fall too, and maybe we’ll try a few different things. If you’d like to learn more about covers crops check out Plant Cover Crops. Dave runs a great website over there and just so happens to be pretty close to our farm, making his data that much more relevant to me.