Why Till Cover Crops Under?

On my recent post about rye as a cover crop, Dan S. comments:

“Um… why would you till it in? Crimp it or chop and drop it, no problem.”

My response:

“Depends on your goal. If you want more nitrogen in the soil for the next crop, till it under at the right time. If you want a carbon mulch, chop it and leave it on the surface. You lose a lot of nitrogen with the latter.”

Also, not to pick on you specifically Dan, but you leave good comments. There is no need to put an “um” at the beginning. It just weakens a statement. Be bold. State what you are thinking directly – I will not be offended.

“Why would you till it in? Crimp it or chop and drop it, no problem.”

Better!

My internal editor greatly dislikes sentences starting with “um…” I am grateful, however, that you didn’t put an “lol” at the end. That would be way worse.

But I digress.

On cover crops, I am no expert. But I do know it’s not a matter of right or wrong in the case of tilling vs. mowing. It’s what you want the cover crop for and how you would like to manage your garden.

As Grow Organic writes in a short article on cover cropping:

(quote)

The three main methods of cutting down cover crops are: undercutting, mowing and rolling. Undercutting is when you draw a blade under the soil and you slice the cover crop underneath the soil. For mowing you’re going to mow down the crop with your lawn mower a weed whacker, or a scythe. This chops the crop up fairly finely and it will decompose quickly. Rolling is basically running your tiller over the plants with the tines turned off. However, this may not always kill the plant and thus not decompose.

Tilling or Rolling

• Tilling it in is the fastest and easiest way to incorporate your cover crops.
• Rototill the crops into the ground.
• The advantages of this method are faster decomposition and less nitrogen loss into the atmosphere.
• The disadvantage is that you don’t get the weed suppression or water conservation while the crop decomposes.

Cut it and Compost it

• You can use a hand sickle, a scythe, weed-eater or mower.
• The advantages are that you’re adding finished nutrient-rich compost back into the soil (eventually).
• This is a great option for raised bed cover cropping.
• The disadvantage is that it’s more work to cut, compost and then add the compost back into the soil and it can take several months instead of weeks.

Mow or Weed-Eat

• After cutting the cover crop down, let it lay on the soil surface as a mulch as it decomposes.
• This will help with water conservation and weed suppression.
• This method chops the cover crop into small pieces and will speed up decomposition.

(end quote)

I love chop and drop. That is my normal method. However, I have also read a good bit on incorporating crops directly into the ground via tillage to rapidly build organic matter while holding nitrogen in the soil for the next crop. Tilling is very easy for me right now as I have access to a tractor. In Grenada, I only grew chop and drop as tillage was very difficult to do.

If you want, you can even let rye grow to maturity, then mow it and harvest the grain. The abundance of remaining straw can then be used as mulch or compost.

Yet tilling it under earlier when green – or mowing it and planting in the stubble – allows you to get your spring crops growing in a timely matter.

Just think about your gardening goals and go from there. It’s not an either/or.

As Dan S. wrote recently on a previous post dealing with green manure:

“Some people, still locked into only one way to do things rather than looking for the most appropriate way to get things done NOW. If it’s not wood chips purists, it’s compost purists!”

I completely agree. We have lots of options in our tool kits.

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