The Growth of Wheat.

New Zealand Mail, Issue 871, 9 November 1888, Page 18

The Growth of Wheat.

JOHN J. WILLIS, SUPERINTENDENT OF LAWES AND GILBERT’S EXPERIMENTAL FARM, ROTHAMSTED, ENGLAND. r ' It is well known that no ordinary cultivated plant can thrive without a sufficient supply of each of a number of substances needed for its food. And the plant has to do not merely with tho supply of nutritive elements as a whole, but also with each of its ingredients separately. Every plant we cultivate, therefore, must have a certain and sufficient amount of each one of the fertilizing agents, or it cannot grow to perfection. The crop cannot rise above the level of the lowest element in the food-supply. It has been shown conclusively in the previous articles upon this subject, that if the manurial or available food*Bupply comes up to the required standard, and other conditions are favorable, a good yield of w heat is certain ; but if any One element falls below the requisite standard the crop must fail in proportion. . - . A soil may be deficient in available nitrogen, potash, phosphoric, acid, or lime ; , or it may be so compact in its texture that air and moisture cannot get into it to nitrify tho crude materials it contains, nor the.roots make their way through to obtain the food that has been made usable. It may, on the other hand, be so loose and non-retentive that the good-ingredients will escape in the drainage water through the soil. It may be so dry that fertilizers will be dormant, and ‘ the plants wither on it ; or so wet and cold as to prevent their growth. Most agriculturists have had experience of tho conditions mentioned, but we venture to assert that by proper tillage and amendments the texture of the soil we have to deal with may be improved, its power of holding water and supplying plant-food increased, and then j by suitable manuring it may be brought into Buch condition as to yield bountiful returns for all that is expended on it. It is extremely important that all engaged in the cultivation of the soil should consider the structure and peculiarities of the roots of the plants they wish to grow. While the power of plant-roots to adapt themselves to circumstances iB very considerable, yet as a rule they develop most freely in those directions where there is least resistance to their progress ; that is, where the soil is open and mellow, and where there are abundant supplies of available food. Thus it occurs that the roots of any plant may sometimes be found at some places to have grown near the surface, and at others at a greater depth, according to the locality of the nutritious food-snpply. From these facts we undoubtedly learn that the more abundant the plant-food the better the roots are nourished and the more they multiply and extend through the soil, making the plants less dependent upon climatic conditions ; and consequently the more profitable is the crop return. While, on the other hand, the roots which find insufficient nutriment remain undeveloped, and the crop harvested is poor and meagre. NECESSITY FOR CAREFUL TILLAGE. We know from experience that all vegetable products require very careful attention to make them thrive and become profitable. It is also a significant fact that the moie man is dependent upon a particular species of plant for his daily food, so much the more

must hia attention be given to its proper cultivation. We know, further, that different plants have very different capacities, by their roots and leaves, of gathering their supplies of food from soil and air, and so when grown in company with other plants, the stronger and often the most objectionable push out their weaker brethren. A few years ago, Sir J. B. Lawes, wishing to see how a crop of wheat would sucoeed if left entirely to itself, year after year to sow its own Beod, and without culture to combat with the weeds, left in one of his experi. montal fields at Rothamstod about an aore of wheat, which if cat and thrashed would have yielded about twenty-five to thirty bushels of grain per acre. This crop was allowed to stand, ripeD, fall, and shed its seeds upon the ground. The usual quantity of seed-wheat sown is from two to three bushels per acre, but here wore nearly thirty bushels of seed left to grow and produce the next year’s crop. What was the result ? The first year weeds and grass began to smother the wheat, and if harvested only about five bnshels of grain per aero would have been realized. This was allowed to fall and seed the ground as before. The second season there was a further decline with a greater luxuriance of weeds. And so on, in each year following the number of wheat plants became fewer and fewer, and their character became so weak and grassdike that it was with difficulty the wheat could be distin guisbed from the surrounding stems of grass. . ADVANTAGES OF CAREFUL WEEDING. various experiment's have been tried to ascertain the positive advantage derived froip carefully weeding one part of a field and.deaving another part undone ; among tho following, made with peculiar accuracy, may be safely relied on : L Seven acres of light, gravelly land were fallowed, arid sown broadcast with wheat ; one-acre whs measured off, and not a weed was pulled out of it ; the other six were carefully weeded. The unwoeded acre produced eighteen bushels ; the six weed acres one hundred and thirty-five bushels, or twenty-two and one-half per aero, which is four' and one-half bushels, or oue-quarter more produce in favor of weeding. 2. A six-acre field was sown with barloy, in fine tilth, nnd well manured. The weeding, owing to a great abundance of charloch, cost twelve shillings per aero. The produce of an nnweeded acre was only thirteen bushels ; of the weeded, twenty-eight bushels. Difference in favour of weoding, fifteen bushels per acre, besides the land being so much cleaner for succeeding crops. 8. Six acres sown with oats, one acre ploughed but once, and unmanured, produced only seventeen bushels. Another six acres, ploughed three times, mauuredand weeded, produced thirtyseven bushels. Ten bnshels of the increased produce may be fairly attributed to the weeding, and the other ten to the manure. It would therefore appear that we are within the truth in saying that where weeds are not kept under there is a loss inourrod of one-fourth of the crop. The weeds rob the growth with which they are mixed of some part of tho food which tho ground holds for the use of plants; they clog the ground mechanically ; they keep air and light from theyonng seed ; while the grain that has ripened under all these disadvantages, goes to the market worse than it would have done had it been grown unaocompanied by weeds, v -