Cover Crops

Early season straw mulch and clover cover crop.

                        Benefits of Cover Cropping

My husband and I were fortunate enough to enroll in a course sponsored by Cultivating Success (http://www.cultivatingsuccess.org/) and Rural Roots (http://www.ruralroots.org/) back in January 2016.  It was called How to Start a Sustainable Farm in Idaho.  This fantastic course was spread over six Saturdays.  The agenda topics included everything from developing crop budgets to various livestock species.  Throughout the course, we were developing our whole farm plan which would be the initial guiding document for our farm.

One of the most interesting topics for me was cover cropping and green manure.  As a lifelong gardener and a wetland scientist, I thought I knew some things about growing plants and soil.  As it turns out I did – a few things.  But not the most important things.

I should have taken a page from the old timers where I grew up.  They would rotate their hay fields with winter wheat.  At the time, I didn’t really think about why, but now I realize they were not growing the wheat for a crop to sell, they were using it for green manure to improve their soil health and increase their hay yield.

So what are these practices?  Green manure and cover cropping are intimately related.  In this blog, I will focus on the use of green manure and talk about cover crops in a later post.  Green manure is a type of cover crop (plowdown crop) that is tilled into the soil to increase nutrient content and improve soil fertility.  Utilizing green manure can create a variety of soil benefits including: increased nutrients, more soil complexity, improved drainage in wet areas, reduce weed growth, attract pollinators….and more.  Canadian Organic Growers, Inc. has a very nice concise explanation of why to utilize green manure (read about it here http://eap.mcgill.ca/MagRack/COG/COGHandbook/COGHandbook_1_5.htm).

The first step to choosing a green manure crop is to determine what you are trying to accomplish in your soil.  Do you need more organic matter to break up hard clay soils?  Are you hoping to improve the nutrients available to your main crop?  Do you want to help prevent weeds or attract pollinators?  These are the questions to ask yourself before deciding on what and when and how to plant green manure crops.  Our garden was a hay field a year ago.  Before that, it had very likely been heavily farmed for wheat and/or lentils.  The soil had very little organic matter and a heavy clay component.  By August of our first garden year, it looked and felt like dried cement.  A soil test showed that it was also nitrogen deficient.  It is always a good idea to have your soil tested before making decisions about cover crops.  You may be surprised at what you learn.  Most University Agricultural Extension offices can test your soil for a minimal cost (ours was $45).  We noticed too that there were not a lot of bees in our garden – even during the height of blooming.  I ended up pollinating my squash manually every morning (seriously!) just to get a fruit to form.  So we added pollinator attraction to our list of ‘wants’ in a green manure cover crop.

Okay – we knew we wanted to use one or more cover crops as green manure this year for three purposes – weed control, attracting pollinators, and improving nitrogen and organic content.  I did some research online and bought a fantastic book called ‘Managing Cover Crops Profitably’ by the Sustainable Agriculture Research and Education Program (http://www.sare.org/).   You can download it for free here http://www.sare.org/Learning-Center/Books/Managing-Cover-Crops-Profitably-3rd-Edition.

If you do not know about this organization – you should.  They have fantastic resources for farmers that are free or very affordable.  Each state has a coordinator that works with farmers to provide learning opportunities, grants, and other resources.  They have fantastic publications on their website – I definitely recommend checking it out.  The book discusses each species of cover crop in depth and provides tables that help the farmer choose the appropriate cover crop plant for their desired results and their climate.

We decided to use Mammoth Red Clover for weed control and soil improvement in between our vegetable rows and buckwheat around the perimeter to attract pollinators.  Clover is also an excellent attractor for pollinators – so it was a home run for us.  We purchased our seed from Johnny’s Selected Seeds (http://www.johnnyseeds.com/).   I got a pound of each to start with since I wasn’t sure how much I would need and I don’t like to have a lot of leftover seed to try to store over the winter and keep the rodents out of….

I got my cover crops planted and they grew very well.  A couple of lessons learned: don’t plant cover crops too close to food crops and make the rows wide enough to use a push mower.  I had a little issue with the clover getting tall enough to shade out the adjacent bean plants.  I invested in a $10 used push mower at the local antique store that I will use to keep it cut next year.  In a couple months, I will have my soil tested again to see if we have seen results.  Most information suggests that it takes at least two years to see soil improvement so we may wait one more year to pay for the soil testing.  For now – we are happy with the weed smothering ability of the clover between our rows.  The buckwheat did seem to successfully attract pollinators.  We had a lot more bees in the garden than the year before.  Overall, our first attempt at utilizing cover crops was a success and with a few tweaks I think we can continue to improve.

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