CHARACTERISTICS OF THE WHEAT CROP.

Otago Witness, Issue 3031, 17 April 1912, Page 14

CHARACTERISTICS OF THE WHEAT CROP.

One of the most critical times in determining the yield of the wheat crop is in the winter months of the year. If the wheat be sown late in the autumn it spends the next three months almost wholly in developing its system of roots. Should the seedbed not be firm, the weather wet, and the soil saturated the root system is restricted, and the plant never seems able to recover completely. The seed should therefore be got in before the dead season of the year begins, and if the roots are well established before winter the plant will have a double chance. Other things being equal, growth is much more rapid in a properly-prepared seedbed, and time enough should be taken to get the ground into perfect order. Some endeavour might be made to show that this is the secret of growing heavy crops of wheat, A 30-bushel crop of wheat will remove 331 b of nitrogen, 14.21 b of phosphoric acid, and 9.31 b of potash (the chief ingredients of the plant food) from the soil. Now the variation in the analysis of soils is not great between one soil and another in a wheat-growing district. Perhaps the greatest variation will be in potash, and the quantity of these food supplies i 6 enormous. A layer of soil 9in deep, covering an acre, weighs about 2,500,0001 b, and one-tenth per cent, of nitrogen would represent 25001 b per acre, sufficient for over 70 crops of the size mentioned. Yet wherever crops are grown continuously the yield comes down with a run. That follows because many of the compounds of nitrogen are of no service until they have been transformed by bacteria into ammonia and nitrates. In this same way phosphoric acid and potash must be brought into solution before they can be taken up by the plant, and that depends largely on the nature and physical condition of the soil. We therefore see that the provision of an acceptable seedbed for wheat means o great deal more to the crop than simply providing suitable ground in which to sow the seed. Those farmers who grow potatoes know that the best crop of wheat is obtained after this fallowing crop. And know also that wheat is sown without much previous preparation of the ground. As a matter of fact it makes the greater part of its growth during the coole rportion of the year when bacterial activity in the soil is low. But following potatoes, the extra working of the ground and the bacterial activity of the warm portion of the year has liberated considerable quantities of nitrogen. And for the rest this crop has a long period of growth and an extensive root system which enables it to forage pretty thoroughly for itself, and secure all the phosphate and potasli it requires from soil which is in fairly good condition. Hence, when wheat follows wheat the value of a nitrogenous manure is evident. On land infested with grub the use of the Norwegian harrow and crosskill roller would have a beneficial effect before sowing. These implements would kill the grubs, and leave a rougher surface than the plain roller, which would be a considerable protection to the young plants from frost and cold or drying winds. The ravages of smut not only involves a loss to the farmer in yield, but has a detrimental effect on the quality of the produce. It is therefore extremely desirable to adopt some precautionary measures for the prevention of smut. On a normally fertile soil no mineral manures are required for wheat, but, as already indicated, it will respond to nitrogenous manures should the land not already be in high condition. The processes which produce nitrates out of the residues in the soil cannot be in a. very active state at the time the wheat chiefly requires its supplies. Hence the value" of nitrogenous manure to wheat in the spring, while phosphates and potash are practically thrown away on land fit to grow a reasonable crop. On lighter land phosphate manure may be added at the time of sowing in the autumn.