Compost, Green Manure, and Intercropping

It’s been a little while since my last post, and for most of that time I have been contemplating the detail of my vegetable/grain polyculture, how the crops will be rotated, and how I will incorporate compost, green manures, and intercrops into the system. I waited, in the hope that I could post the finished article, but have to admit, that I still have a bit of thinking to do.

The problem has been trying to get the PERFECT system, whereas I may have to compromise on perfection, and settle for just pretty good. It hasn’t helped that I’ve learnt more during the process, which has added some complexity.

What I hope to do is explain what I’m aiming for, why I’m doing it, and outline where I am now. What follows is for my larger vegetable growing area.

Initially it all seemed quite simple.

The first aim was to keep an overwinter cover/vegetable crop on the whole of the plot. This is the best way to preserve mycorrhizal fungi, which in turn is the best way to improve yields, and maintain phosphorous levels.

The second aim was to maintain levels of organic matter, and nitrogen levels, by the use of leguminous green manures, either as intercrops , or as a cover crop after harvesting.

The third aim was to decide where were the best parts of the rotation to apply compost.

The complicated bit was to fit all of that in with the needs of the crops. The first part of my rotation is a cereal/bean/clover polyculture, designed to build fertility, provide grain and beans, and give materials for composting. This is described in some of my recent posts. The cereal part of the rotation uses the Bonfils method, with both annual, and perennial grains. I hope to add corn, and soybeans to the last year of the grain section. The corn will cash in on some of the fertility accumulated by the cereal/legume break, the soybeans will add more nitrogen, and are supposed to reduce the microbe responsible for potato scab, and potatoes are the next part of the rotation. The potatoes are another heavy feeder, and help to reduce the weed burden. Unfortunately, late potatoes are difficult to follow with a legume. The normal green manure to use is cereal rye, which can be sown in October/November, but is not really ideal for my system, as rye is included in my cereal break. I could have added another cereal break, or used compost after the late potatoes, or placed the potatoes later in the rotation. The early potatoes were less of a problem. Any of the legumes would have worked for them. My current thoughts are that I’ll follow the potatoes with leeks, onions and garlic. I normally transplant leeks into the beds vacated by early potatoes, and garlic, and overwintering onions will be OK to follow maincrop potatoes. I had thought that I would use compost to mulch a section of the space for spring sown onions, but it might be better to grow the leeks and autumn alliums down the center of the beds, to act as a winter reservoir for the fungi, and then plant the spring sown alliums alongside them, to benefit from the active fungi, later. The onion family doesn’t do well with competion, so wouldn’t do well with an intercrop, nor is it supposed to do well following a green manure crop, so following potatoes is sensible.

The leeks are harvested during the winter, and the remainder of the alliums by July, which gives a reasonable spread of time for planting late brassicas. The alliums are not too deep rooting, which should also leave the soil relatively firm for brassicas.The brassicas can be underplanted with a legume, once the brassicas are large enough to withstand competition, and may support a dwarf bean, planted slightly late in the season, for dried beans. I don’t normally grow too many brassicas, so this may be too much space allocated, but could also include swedes, turnips, and winter radish.

My initial rotation was shorter, with carrots, parsnips, and brassicas sharing the space vacated by potatoes, and this may still be best for me. I also grow a lot of  winter squash. I had thought to grow the squash with the corn, but now that I’m intercropping the corn with soybeans, I need to find a slot for them. They may fit in after the brassicas, benefitting from the fertility added by the clover cover crop, and could then be followed by cereal rye, beginning the cycle again.

Working this way, providing that I keep some clover during the corn/soy part of the rotation, the beds will have a permanent cover at all times, and most years one crop is followed quickly by the next.

Most of the other vegetables that I’m planning to grow will fit into the other vegetable area, and include millett, camellina, and cowpeas. In the long term, it may be better to include them into a longer, combined rotation, but that can wait until I’ve thought a bit more, and experimented with this one.

Wishing you well

 

Deano

 

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