The Power of Cover Crops

Cover crops are a very valuable tool if utilized and managed correctly. I've written some about what they are and what they are used for previously, but I'll hit the main points again because I'm sure the subject of cover crops doesn't classify as "information worth retaining" for most people.

Cover crops are plants that have a purpose of not being harvested, but planted for benefits they provide for the soil. Some benefits include increased diversity into a crop rotation, living root in the ground, and mulch when spring comes around. I had the best kind of cover crop - free. In fact it was actually accidental. In the spring of last year when I planted my garden, there were several species that could be considered as cover crops. Some of them I did not harvest in the summer and I just let them grow as much as they wanted. For some of them, one season was not enough.

Towards the end of winter I was starting to see green throughout my garden and first became worried that this vegetation was intrusive weeds that would cost me more time and money dealing with. Much to my surprise, most of this was primarily two species that I had included in my spring mix that decided to stick around. These plants were clover and rapeseed, which are both relatively hardy. I definitely have my fair share of weeds to contend with this spring, which was expected, but I was extremely surprised to find beneficial plants in the majority.

One reason I was particularly excited about finding an abundance of clover throughout the field is the fact that clover is a legume. I planted a couple different varieties of clover so I don't know the exact species, but legumes have the incredible ability to take nitrogen from the atmosphere, store it in the plant, and exude some back into the soil. To do this, a certain bacteria must be present in the soil. As soon as I could, I went out and dug up a couple batches of clover to look at the roots. If this rhizobia bacteria is present, it will form a symbiotic relationship with the clover root and form nodules, or little bumps, on the roots. Sure enough, when I looked I found what I wanted! These nodules tell me that all throughout my garden, atmospheric nitrogen has been taken up by the plant and now will eventually be released back into my soil through root exudates and plant decomposition. Free fertilizer!!

Rapeseed was the other species I saw growing in the field. This is basically a turnip without a tuber. It made it through the winter and now is making a last-ditch effort to go into the reproductive stage, so now I have little yellow flowers from the tops of the stems dotting my field! It and other brassica species that I planted, which are turnips and radish, will die and start decomposing, releasing nutrients back into the soil. Some nutrients are not in a plant-available form for uptake the first year after they are released, so it is more of a slow release fertilizer rather than a boost of nitrogen. Radishes in the garden have pretty much completely decomposed and are skeletons sticking out of the ground. Other plants such as millet, sunflowers, and corn have a higher carbon:nitrogen ratio, which means they take longer to break down than a green bean leaf or foliage. The planter should have no trouble breaking through any residue on the soil, but having plant material on the soil will act as mulch and provide several benefits throughout the growing season.

I was able to intentionally plant cereal rye as a cover crop in my raised beds and two small plots on either side of the beds. Rye is possibly the most used cover crop as it can create tons of biomass for weed suppression in the spring. Rye also has allelopathic properties which means is exudes a substance that can hinder the growth of some weeds before they even germinate. Rye also has a high carbon:nitrogen ratio, so the residue will cover the ground for several months, if not longer based on the microbial activity of the soil. Feeding the microbe workers in the soil is wonderful, but the more you feed them, the more there are which requires more food! And here's a little disclaimer: I "planted" my rye by literally grabbing handfuls of seed and throwing it through the air so it scattered on the ground. No tilling, no making sure it got perfect seed to soil contact, just thrown. In fact, I made a mock test plot for my thesis project in Sparta to calculate how much seed I needed for each plot. The area was 10x15 ft of grass, part of the lawn behind the barn. I threw down seed, only looking for an estimate, and went on my way. This spring, I was extremely surprised to see that the rye had grown almost as quickly as the others and had outcompeted the fescue and other plants in the yard. Plants can be neat.

There definitely are still enough weeds to go around. Most seem to be a plantain variety and will not pose a huge problem to the growing season. I really like free stuff. And when I can get a free cover crop that provides me with free fertilizer, I am all about that. Things are starting to ramp up and planting is set to start very early May. We are starting the season off right so far and I hope that the success can continue all year!