The cropping of all available ground is of the utmost importance for only a limited area of the garden will he available for vegetable growing and the best possible.usc must be made of it. A 4-course rotation of crops should be followed where possible for there are many advantages to be gained by it. The crops will make use of the different plant foods stored up in the soil in varying degree so that one may use up larger quantities of nitrogen whilst another will use up more potash and phosphates. It is therefore important to divide the ground in such a way that one crop may follow another each year in systematic rotation.
Again, to keep the soil in good ‘heart’, it is necessary to ensure that it does not lack lime but whereas certain crops require ample supplies, others e.g. the potato require an acid condition of the soil. Yet if lime is not present, the inert plant foods stored up in the soil will not be made available to the growing crops and however well the ground has been manured, the plants will obtain little benefit. Not only does rotational cropping maintain a balance between the various plant foods but the different methods of cultivation required by each group of plants will ensure that the ground is thoroughly tilled and to a considerable depth rather than merely at the surface. This will open up and aerate the soil and enable bacteria to obtain supplies of oxygen so necessary to convert the manures and fertilisers into food which can be readily absorbed by the crops.
The correct rotation of cropping will also make for the most economical use of the ground for less fertilisers will be needed. For example, cabbages and cauliflowers take large amounts of nitrates from the soil whilst the legumes (peas and beans) actually leave the soil richer in nitrogen, due to the ability of the root nodules to fix the nitrogen in the soil. The ‘green’ crops should therefore follow beans and peas and with the ‘greens’ may be grown the salad crops or the salads may be grown as ‘catch’ crops in each section. Moving the crops around will also prevent the accumulation of those pests and diseases in the soil which may be endemic to one group of plants, whilst to grow the crops in rotation will prevent the ground from building up an adverse reaction to any specific plant. This is known as ‘soil sickness’ and makes for continually decreased crops. When moved to fresh ground, the plants will show a much improved vigour.
On even the smallest vegetable garden, rotational cropping should be practised. First manure one part for the potatoes, planting early, second early and main crop varieties. They will clean the ground as no other crop will do and by moving them around the vegetable garden, this will ensure that the soil is kept free from weeds. A heavy application of manure for potatoes will mean that only limited supplies will be needed for other crops during the next three years and until the ground is made ready for potatoes again.
Root crops should follow potatoes and they require a soil which is not deficient in lime, whilst they always do better in one which has been manured for a previous crop. Fresh manure causes the roots to grow forked whilst it is also detrimental to their keeping qualities.
Follow root crops with legumes of all kinds and which will increase the nitrogen content of the soil and make it available for the ‘greens’ which will follow the peas and beans. For the small garden, the rotation will be as follows:
The larger garden will be able to grow a larger number of varieties in each section which will give a greater spread of vegetables throughout the year but the cropping rotation should be the same. This is, however, a general rule and it must not be thought that between rows of peas and beans and other crops, lettuce salad crops be grown. As they will occupy the ground for only a short time, and it is necessary to crop the land as intensively as possible, salads are ideal for planting between most other crops for they will have been removed from the ground before the other plants reach maturity.
There are also those plants which follow no definite rotation (celery is one) because the ground must be trenched each year. The plants, however, will benefit front being planted in fresh ground as frequently as possible.
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