Should I compost my cover crops or turn them under?

18 years ago

Hi, I'm just beginning to use cover crops, not only to improve the soil but (hopefully) cut down on the nematode/disease problems.

I have a small, fairly intensively planted garden, and I have no tiller.

My question is, Should I a) pull up the cover crop and compost it (would this ruin the nemicidal benefits?) b) cut the cover crop down, compost the tops and spade in the roots or c) cut it down and turn the whole cover crop into the soil?

I'm aware that there's also option D) the no till method, cutting it down and letting it stay on the surface, but this time around I want to try "working the soil."

I'm leaning towards C), but I think I should not let the cover crop get very big because it would be more difficult to turn in and slower to break down.

The cover crops I plan to use most are sunn hemp in summer, maybe some cowpeas, and the rest of the year mustard, kale, and marigolds.

Any advice or information on this would be appreciated. Thank you!

Bill

Featured Answer

jsfink

18 years ago

I also have a small, intensively planted garden, and found alternative (D), no till, to give best results. You should reconsider going that route. I cut the cover crop (a mix of cereal rye, annual rye grass, crimson clover, hairy vetch and winter peas) close the ground with a weed wacker, covered the cuttings with a layer of finished compost, and topped all of that with mulch. No digging, expect where I made holes for seeds or transplants.

The vegetables that year were the best tasting and most productive in 20 years, and the insect and disease problem was quite low, since the plants were so vigorous. I think the layers invited all sorts of beneficial organisms and diversity in the soil, and the plants were living in a healthy environment, where they were able to take care of themselves. Keep in mind that the roots are already in the soil, and organic matter is getting down there just by leaving things alone, no need to turn a thing. By the end of the season, the surface organic matter is also decomposed and worked into the soil by worms, bacteria, etc.

Tilling in is a good idea to create a first time bed, to get organic matter into the soil, and in my area to get the rocks out of the bed. After that, I have discovered that the tilling is a short term fix. It introduces so much extra oxygen into the soil, and this creates a bloom of bacteria that speeds up the decomposition. This might sound like a fine result, but it is actually counterproductive in the long run, since the organic matter gets consumed much faster, and needs to be added more frequently.

I am not religious about this. In fact, tilling and turning the soil used to be my favorite thing about gardening. From trial and error I've mostly given it up, since the long term soil building, and the better growing results, are pretty evident to me from not tilling where it is not really necessary.

I know this doesn't answer the question, since you said you were going to till. In that case, I'd till in as much of the organic matter as possible, tops and roots, since it will be a net loss if you add the oxygen but not the food for the bacteria population that will explode in the super-oxygenated soil you will create.

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Comments (6)

macthayer
18 years ago
It is my understanding that tilling in a cover crop is best. That is what I have done in the past when I have used one, and it worked very well, although I admit that I haven't done it often. My tiller gave out a few years back and I decided not to buy a new one because I didn't use it much and it spent most of its time taking up space in the garage. Now when I want a tiller, I rent one for the day. Perhaps you could look into doing that?
MacThayer
softmentor
18 years ago
I would do neither. I'd mow it, scalping really, very close tot the ground, then just let the mowings be part of your mulch. Leave it laying right on top of the soil. Every time you spade the soil, you ruin the natural horizons that soil will develop when left unturned. Also the organic material will have more benefit when used as mulch than when turned into the soil.
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dchall_san_antonio
18 years ago
I agree with softmentor. Roots belong under ground and tops belong on top. When you till you mix all that up.

If Mother Nature had wanted the soil tilled, She would have covered the world with pigs instead of wall-to-wall herds of cattle, sheep, antelope, horses, deer, etc.
Kimmsr
18 years ago
The reason for growing a cover crop, in addition to helping keep your soil from eroding, is to add more organic matter to that soil and pulling it out and composting it would be counterproductive. A cover crop should be left in the soil it grow in, however, there is no need to till it in and there is no need to mow it down, just lay the cover crop down and cover it with newspaper and cover the newspaper with something to hold it down and hide it and the soil bacteria will incorporate that green manure into the soil for you.
plantnfool
18 years ago
THe truth is it really doesn't matter if you have plenty of time. If you need the benefit of organic matter in the soil this year, you would do best turning it under. If you already have plenty of organic matter in the soil just cover it with a smother layer. The worms will do the rest over time. The worms will do the tilling for you if you have a few to start with and give them what they need to multiply. The soil bacteria and fungi will do their part but the worms are the ones that will do the tilling in and mixing of the cover crop with the deeper soil. Good luck. The plantnfool