PLOUGHING IN GREEN CROPS.

Hawke's Bay Herald, Volume 13, Issue 1015, 19 January 1869, Page 2

PLOUGHING IN GREEN CROPS.

It strikes us (says the Sydney Mail) that . ■•■ in several parts of this Colony where the soil, is deficient in organic elements, the produce of decaying vegetation, &c., and where farmyard manure is not to be had, fertility might be imparted by ploughing in green crops. The principal crops sown in England are white -mMtarb^ buck wheat, and lupine. They- grow" best on light soils, make rapid progress, and are attended with little or no expenses in cultivation. The poorest, sandiest soils, requiring manure for every crop, have been made productive by means of green manuring. On Bagshot Heath lupine has been employed with wonderful effect. The writer has used white mustard on soils apparently destitute of any vegetable debris, and got great crops of grain afterwards. The mustard being sown on the fallow, during the summer, shot up to a height of A or 5 feet in six weeks, and was then ploughed in. Some readers will wonder how this was done.. It is a simple process.. The plough is fitted, ; with, a chain and weight attached to the coulter. The weight is trailed in the furrow about middle way of the mouldboard. This presses the. green stalks down into the horse way, just in advance of the furrow slice, which holds it in position. Sometimes a heavy roll is passed over the crop before the plough, and the heavier the better. A two-wheel pressor is the best implement for effecting a thorough consolidation. The seed for the grain crop to follow is drilled across the work, about three weeks after the ploughing, and generally a robust heavy crop may be expected. This is an operation attended with the best effect in porous sandy soils thaO do not possess the power of storing up a quantity of ammonia in a soluble state, which is taken up by the roots according to the requirement of the plant. This only affords an illustration of the statement often made in these columns, that the soil is a mere medium for the growth of the plant ; it may be emptied of its fertilising properties, and it may be filled — one .crop may exhaust the soil of its powers of reproduction, but a different crop may find untouched a supply of- food sufficient for its wants. Eor reasons we have already given, sandy soils, such as those of Cumberland, are deficient in organic materials, and are, consequently, destitute of the means of acting upon phosphatide and potash fertilisers when naturally present or artifically applied. To plough in large quantities of succulent foliage in such circumstances, therefore, must be a very rational proceeding, anc^ one that would yield a large return upon the outlay. Seaweed in some seaboard districts might Ibe applied with great advantage. On the \ eastern coast of England it is applied on the stubbles direct from the beach at the rate of twenty to thirty tons per acre, and at once ploughed in for the succeeding crop. A farmer who has used seaweed exclusively as a manure for many years says : " The land has been under wheat and potatoes alternately for a long, series of years, without deteriorating the value of the land or decreasing the quantity of the produce, the tenant paying an annual rent of upwards of £5 per acre." Great benefit is derived from the use of the leaves of turnips and mangolds. . Most farmers spread them over the land and plough them in ; also potato haulms, just as good vignerons always return the vinedressings to the soil. The average weight of the tops from a good crop of turnips may be about 4 tons per acre. Considerable difference is observable in tho benefit which follows this operation, it being much greater when the rainfall is abundant, owing probably to the solubility of the mineral element contained in the leaves being thereby accelerated. Some readers who come to this subject for the first time may not understand the rationale of this proceeding. They may perhaps be asking themselves what can be the advantage of ploughing back to the earth merely the elements that have been obtained from the earth. If there are any whose thoughts run in this direction, it is clear that another word of explanation is needed. We will adopt the words of a practical farmer : "If plants derived all their substance out of the soil, and gave it back in the same state of chemical combination in which they drew it forth, they would affect the soil none otherwise than by the accidents, of their culture. But by far the largest portion of the bulk is derived not from the soil at all, but from air and water, and the whole of this is contributed by green manure as clear gain preparatory to the succeeding crop • whilst the remaining portion, though extracted from the soil, is brought into new affinities, assuming more available forms than before, so that even this, as returned to the soil by green manure, is in a more advantageous condition for rapid assimilation than if it had not recently played a part in vegetable growth. The plants most appropriately employed for green manuring are those that derive their support principally from the air. As the inorganic portion of these plants decays in the soil, the inorganic part — that is saline and earthy matter — is liberated. Thus living plants obtain from the remains of former races buried beneath the surface, a portion of that inorganic food which can only be derived from the soil, and which if not thus directly supplied, must be sought for by the slow extension of their roots through a greater depth and breadth of the earth in which they grow. The addition of manure to the soil, therefore, places within the easy reach of the roots, not only organic but also inorganic soil."