What Is A Cover Crop?
At the end of the summer harvest, when all the veggie plants are dead and gone, it’s time to till the soil and work plant debris back into the dirt so that it decomposes over the winter. But, that result in bare soil – with nothing growing except for the occasional unwanted weeds that pop up sporadically.
That means NO FOOD for the bacteria, worms, and other microorganisms in the garden plot to eat – for many months. These little buggers are needed to keep the garden soil healthy and fertile. If we don’t feed them, they die – or move on to greener pastures.
So, let’s make our garden a greener pasture – and add a fall cover crop that not only feeds these tiny critters but also adds nutrients to the soil in time for spring planting next year.
There are two basic classes of cover crops – or “green manure” crops. Each one performs a necessary function for the soil in a backyard garden.
Grains And Grasses
Cereal grains and grasses catch and hold the nitrogen, minerals, and other macronutrients and micronutrients that are normally leached out of the soil during the winter rain and snow. So, the amount of fertilizer needed each spring to get the garden underway is significantly minimized. That equates to a lower out of pocket expense to get to growin’ again in the spring.
They also prevent erosion and keep the soil from compacting so tightly – making it easier to till in the spring. Their roots penetrate deep into the soil and improve the penetration of both air and water. Good drainage is essential to a successful summer garden.
These grains and grasses will smother the weeds and keep those weeds from actively proliferating in the garden. Additionally, they can not only force some garden pests to move on to other areas – they can also break up disease cycles – minimizing – and, sometimes, eliminating completely – bacterial and fungal plant diseases.
The best part is – when you till the cover crops back into the soil, the nitrogen and all the nutrients – including phosphorus, potassium, calcium, magnesium, and zinc – are ready to feed your spring veggie plants. That’s why many folks call cover crops by another name – “green manure.”
NOTE: It is best to till cover crops back into the garden dirt at least a month before spring planting to give them time to decompose sufficiently and add their nutrients back into the ground. Before tilling, run your mower or garden tractor over the cover crops to chop them up. This will definitely make your life much easier when working the plant debris into the soil.
Triticale, barley, buckwheat, oats, winter wheat, winter cereal rye, and annual ryegrass are popular cover crops. My choice is annual ryegrass because it grows very fast – not giving the weeds a chance to take hold – and it is, by far, the least expensive of the all the choices.
This year I purchased a 25 pound bag of Pennington Annual Ryegrass. Using a Scotts Broadcast Spreader, I distributed it at a rate of a half a pound for every 200 square feet of garden space – and, in my ~ 2,000 square foot garden, I’ll use about 5 pounds. So, a 25 pound bag should last me about 5 years.
Seeding the garden with legume cover crops has the same advantages as using grains and grasses – with one added plus! The legumes will add additional nitrogen back into the soil – since they are “nitrogen fixers.”
A host of nitrogen fixing legume cover crops include: alfalfa, clover, peas, beans, vetch, etc. I have found what works well for me is a 25 pound bag of Austrian Field Peas.
I mix the peas in with my annual ryegrass at the same rate – half a pound for every 200 square feet of garden space – so, again, 5 pounds. That way, I don’t have to order any more ryegrass or field peas for 5 garden seasons.
Other Cover Crop Combinations
Many of my fellow gardeners like to use hairy vetch, along with either ryegrass or oats.
Others lean towards sowing a winter wheat along with their field peas.
It all depends on what grows best in your neck of the woods and how big your wallet is. And, since annual ryegrass and Austrian field peas cost less and do the job, I will always opt for these low cost cover crop solutions. Also, my neighbor, Jed, the retired farmer, recommended this combination to me since I grow a lot of corn. He said the ryegrass and field peas do a better job of adding essential nutrients back into dirt – because corn can deplete the soil more than many other vegetables.
Don’t Let Cover Crops Go To Seed
If you allow them to spread seeds in the garden, they will grow just like weeds during the growing season – trying to crowd out your veggie plants while competing for water, nutrients, and space. This is especially true of legumes like hairy vetch, clover, and field peas. But, even the grains and grasses will give you a headache trying to keep them from overtaking your summer garden.
So, keep an eye on them – and nip them in the bud before they start tossing their seeds all over the place!
Do You Still Need A Soil Test In The Spring?
You betcha! Get that soil test!
You still may need to fine tune the pH of your soil with a bit of lime or sulfur/potash – or, you may be a tad bit off with some of your macro or micro nutrients – and need a little fertilizer. However, I guarantee that the amounts you use will be a drop in the bucket compared to what you used in the past to get your spring garden soil up to snuff – before you discovered the value of cover crops!
Now, tell me – have you used cover crops? Ever thought about using them? How much do you spend every year on soil amendments? Let me know in the comments or by email!
Jim, the Lifelong Gardener