Because gardening is an intensive cultivation, it is rarely possible to devote considerable areas for lengthy periods to the growing of cover crops to turn under. Cover cropping or green manuring is therefore less extensively practised by gardeners than by farmers. Nevertheless, its possibilities must not be overlooked. Ordinarily the gardener's green manures must be kinds that grow quickly and can be incorporated with the soil in a few weeks, or at most, a few months from the time of sowing.

Only under exceptional circumstances can he consider a crop - such as lucerne or red clover - that will occupy the ground for a year or more. Among the most satisfactory green-manure crops for gardens are leguminous plants such as tick beans, field peas, New Zealand blue lupins, cowpeas, purple vetch and lucerne. Good non-leguminous ones are rye grass, oats, millets, barley and mustard. The general procedure is to prepare the beds and then add one part by volume of superphosphate to four parts of seed, mixing in thoroughly.

Alternatively, add one ounce of superphosphate per square yard of soil. Broadcast the seed or sow in drills in moist soil. Leguminous crops should be turned in when beginning to flower, as the storage of nitrogen is greatest at this time. Other crops, such as oats, can be dug in when about 18-24 in. high. Knock the crop down in one direction, chop up into short lengths with a spade and mix into the soil as thoroughly as possible. Alternatively,
cut it down to the ground in 6 in. stages with a pair of hedge shears, then dig in. Decomposition is accelerated if a light dressing of sulphate of ammonia or blood and bone is given. A crop of lupins sown in March will be ready to turn under in July or August. Gardeners with restricted space may prefer to sow green peas from which a picking can be had before digging under.
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