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Monday 14 January 2013

Different manures and their effects on earthworms.

Yesterday was a mild day, perfect for clearing the ground and preparing for planting. Whilst forking over the various plots I couldn't help but notice the differences in the soil structure and earthworm densities and sizes.

My vegetable plot is divided into four equal areas which correspond to a simple rotation system. The beds all lie next to each other with just a narrow earth path between.
The rotation system is potatoes, followed by legumes, then brassicas and lastly alliums which also includes carrots. This works for me because I grow enough of all the four main groups and the manuring is simple and suits the various crops. Over the years the ground has now had each of the crops at least once and is on its second cycle. In the past the ground has been ploughed for oats but has been pasture for many years before I started working it. I am lucky that it is a good loam soil but am still surprised by the number of stones and even large rocks I keep digging up.

Potatoes start the cycle because they were used to first break up the ground. They are given a general fertiliser, usually chicken pellets, on planting and then a top dressing of homemade compost when they start to grow and need earthing up.

The legumes follow potatoes because they fix their own nitrogen and enjoy the remains of the compost left by the potatoes. I put seaweed on their bed during the winter to cover the soil. It also seems to deter slugs come the spring.

After the legumes are lifted the bed is forked over and fresh manure from the chicken and goose shed is laid thinly over the surface. This is covered by black plastic. Over the winter this starts to break down and is incorporated slowly into the soil by the worms. In the spring I add some lime when planting pot raised brassicas and have had fabulous crops as they enjoy the nitrogen from the manure. I do not raise any salads on this bed during the year because of the fresh nature of the manure, although by summer it will be 6 months old.

Finally alliums and carrots follow the brassicas and no new compost is added. They mop up any remaining nutrients in the soil and leave it ready for the potatoes again. Seaweed makes a good cover for the bare winter soil prior to the potatoes going in during the late spring.

Digging the potato patch this winter after a poor harvest, thanks to last years cold summer, I noticed how grey and barren the soil looked. Then I remembered that the bed had had no compost added to it during the year because there had been hardly any potatoes to earth up, (had I tried I probably would have buried them!)

Going onto the legume bed, still sporting some dried seaweed and barely any weeds, I was astonished at the difference. This bed had had a previous dressing of compost (when under potatoes) and a winter dressing of seaweed, through which the peas and beans had grown. The soil was darker, held together better and the quantity and size of the earthworms was tremendous. Each forkful brought up large dark mature worms and small bright pink young worms. The distance between the beds was barely 60cm.

The brassica bed also yielded good quantities of worms still working in some of the straw from the winter dressing of poultry manure. Again there was a better holding quality to the soil and it was darker than unworked soil. Already parts of this bed held bulbs of garlic and I have good hopes of as good a harvest as last years.

The situation in the potato patch needed remedying and luckily I have plenty of homemade compost. A thin top dressing should ensure the worms migrate back and I covered the bed with black plastic to keep it warm whilst they work it in. A trip to the beach should yield plenty of seaweed for a good covering and then the legumes and worms should be happy. Not long now until planting starts again.

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