Sunday, April 19, 2009

Compost and soil

After swapping comments with Compostwoman, a few lines on compost, and soil generally, seem in order.

I did a talk at our Horticultural Society a couple of momths ago, entitled "Why Organic" - quite a proportion was on soil; for it's like the character from Beyond Our Ken, or was it Round The Horn, used to say: "The answer lies in the soil."

So much of what we do as organic gardeners is devoted to helping improve the quality of the soil isn't it? Depending on geology, geography and historical use of that ground, we all start with varying types and qualities of soil, from pure sand (the part of Wirral where I grew up) to pure clay (in part of my Dorset garden now). The chap who once lived in our house, before the lady we bought from, looked after a neighbour's garden when we first moved here, so I had long chats with him over the hedge and I was delighted to learn that my veggie plot had once been home to a couple of pigs - they're great for turning over the soil and manuring it.

What is needed to improve the soil? I'd say time and crop rotation. It has taken me 6 or 7 years to have a good soil.

Crop rotation is always advised to prevent the build-up of diseases isn't it, and it is also the basis for continual soil improvement.  I use a 4 year rotation: 

1. Potatoes, which have lots of manure and compost added to the soil; followed by: 
2. Peas, beans, onions, shallots and garlic which all like the moisture retention of the left-over organic material added for the potatoes (and they get mulch round them too), and in the case of peas and beans (if you leave the plants and especially roots in the ground to rot back in) fix nitrogen in the soil, ready for the next hungry crops in the cycle: 
3. Brassicas which get loads of compost added ready for them, so by the time the last in the cycle arrive, the soil won't be as fertile. The last is: 
4. Roots and if there is too much soil fertility they fork like mad - great for the funny vegetable in the Summer Show, but a pain in the kitchen! They like low fertility compost and a mulch. Then it's back to 1. potatoes again and so on ...

On top of that if there is bare soil and there is time for it to grow plant green manure and if there's not cover with a mulch (garden compost, leaf mould, chopped straw).

Even a very small plot can follow a rotation, so if you are starting with just a couple of beds (you can mark each into half - there's your 4 for rotation) you don't have to miss out on the marvel of soil improvement.

At just about every stage there is plenty of organic material to be broken down in the soil and keep the worms happy, and if they are happy so is the soil.

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