Novel Equipment and Ideas for Using Cover Crops on Vegetable Beds
December 20, 2017 Video transcript: Having the right equipment for managing cover crops is critical. Here are some of the innovative cover cropping equipment that we’ve been developing and dreaming about developing.
But let me start off with a story of my first experience planting the winter cover crop in the organic research farm I started managing several years ago.
The soil on that farm was in bad shape and needed lots of cover cropping to turn it around. So, when I’ve planted that first cover crop, I used a typical grain drill. I remember how good it felt as I pulled that drill back and forth across the field planting the cover crop and thinking about all the good things I was doing for the soil.
After I’d planted about half of the field, I figured I better go and check to see how much seed was left in the hopper.
Unfortunately, one side was completely empty, and I had no idea where in the field the seed had run out. I didn’t want my first planting to look like I didn’t know what I was doing, with big gaps where the weeds would grow. So I reloaded the grain drill with seed, and I replanted the whole field again.
How to Modify Equipment for Cover Crop Planting
I’ve learned a lot about cover crops since then and I’m now much more comfortable with the various features on standard planters.
But I’ve also come to realize these planters, and a lot of the other tools that we use to manage the cover crops, have their limitations and aren’t always well-suited for the high-value cropping systems that I work in. And I think this is part of the reason that cover crops aren’t as widely used as they should be.
So the novel system and equipment I will focus on involves growing cover crops on beds in the same row spacing that we use for many of our vegetables.
My colleague Jim Leap modified our Stanhay precision belt seeder to plant our cover crops. Seeders like this work really well with round-pelleted seeds, and it’s been the standard planter for most of the lettuce industry for more than 50 years. They are great planters because they accurately space individual seeds within a row.
But we don’t need that level of accuracy with a cover crop, and it wouldn’t make economic sense to pellet irregularly-shaped cover crop seeds. The pelleting process is pretty expensive.
So we removed the seed metering units and added multipurpose hoppers that deliver the seed right down to the bed where it’s needed.
With the modified planter, we planted rye cover crop in two lines on four beds.
The Advantages of Planting only Beds
The first potential advantage of cover cropping on beds is that we use about 60% to 70% less seed than with a standard planting arrangement without beds. With a standard cover crop planted with a grain drill, there would be several more seed lines per unit area. While having a densely planted field shades the soil quickly and suppresses weeds, with a bedded cover crop we manage the weeds differently (i.e., with cultivation).
About nine days after planting, we used a rotary hoe over the cover crop to uproot weeds that aren’t as deeply embedded as the cover crop.
We like to follow the rotary hoe with a standard vegetable cultivator about a week later, and this helps to take out remaining weeds that may be in the furrow bottoms or on the bed top and might have been missed by the rotary hoe.
The cover crop then fills in the bed top and shades the furrows, giving us a nearly weed-free cover crop that’s still extremely productive.
If the weather cooperates, we can take out several weed fleshes during a single winter and this really helps to reduce the weed seed bank.
How We Mow the Cover Crop
When the cover crop needs to be mowed, there are some real benefits to having our own beds rather than having it in a standard un-bedded arrangement.
The wheel tracks of the tractor in a standard cover crop push down the cover crop in front of the mower and this can leave long unmowed strips through the field that are difficult to incorporate into the soil later.
In contrast, with a bedded cover crop, the wheels run in the bare furrow bottoms and this allows us to cut the cover crop into smaller and more uniform pieces and also mow the cover crop closer to the soil surface.
Another potential benefit to cover cropping on beds is it allows us to control the growth of the taller cereal component in a legume/cereal mixture.
For example, a big challenge with a rye/vetch mixture is that the rye starts to flower before the vetch. With our cover crop on beds, we can actually mow the rye seed heads off in the upper canopy to prevent them from setting viable seed, and then let the vetch vines get a little bit more light and grow a little longer to potentially fix more nitrogen.
Cover Crop Strategies I Want to Develop
Let me share a few ideas of some innovative cover crop management strategies and equipment that I’ve been dreaming about developing.
Earlier this year I wrote a paper that addresses the complicated question about cover crops and sustainability. I described several different cover cropping strategies.
Probably the most novel idea involves extracting nitrogen rich juice from cover crop shoots, and use it as a liquid fertilizer in subsequent vegetables.
The juicing strategy involves harvesting cover crop shoots from beds using a forage harvester. I would actually pull a trailer to catch all the harvested shoots, and then they would be processed to extract the juice.
And as we’ve been experimenting with the forage harvester, I’ve been wondering about another way to use it that doesn’t involve juicing. And this idea came to me when we were trying out the forage harvester after some broccoli.
Can We Use Harvest Residue as a Mulch?
What really impressed me is it cut the broccoli right at the bed top and then lifted the residue off the bed top, leaving it really clear. The bed top was actually so clear that it looked like you could plant your next vegetable right into it with almost no tillage.
So we’re going to try modifying the hood of a forage harvester so that the finely chopped material that’s pulled off the bed can be channeled back down and into the furrows between the beds, leaving the bed tops free of residue.
We could then lightly strip till the bed top if we needed to and then plant our next vegetable. This would leave the residue in the furrow bottoms as a mulch where it would decompose slowly and then provide a lot of other benefits.
I like Legos. They inspire kids to be creative and adults, too. And as we develop new tools for cover cropping, I often feel like a kid with a Lego set. It’s a lot of fun seeing what you can come up with. So stay tuned as we continue working on innovative cover cropping equipment and strategies.
I think these have got a lot of potential to increase cover crop adoption and make the systems that I work in here far more sustainable.
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