THE RURAL WORLD.

King Country Chronicle, Volume V, Issue 368, 10 June 1911, Page 3

THE RURAL WORLD.

POTASH MANURING. The use of potash manures is not as general as it should be, specially in the light lands of the Dominion. For many years farmers have pinned their faith on bone and super, as their onlyfertilisers, all unaware of the fact that besides the phosphates which they supply, the plants are in need of other forms of food which these do not contain. The three main elements of plant food which it is necessary to apply artificially are nitrogen, phosphoric acid and potash. The first of these is not so urgently required as the other two, because in our comparatively virgin soil, except where exhausted by cropping, the organic nitrogen in the form of humus, or decayed vegetable matter, is not yet exhausted so that the chief need is the application of the others. Phosphorce acid has been liberally supplied through the medium of bone, super, guano, slag, bone char, etc., but for years the necessity of using potash in addition has not been suspected by the average farmer for the very good reason that his crops were so good without it that he was quite satisfied to go on in the old groove. There was good reason for the neglect of potash manuring in the early days for the simple reason that there was sufficient naturally in the soil in a fairly soluble form to supply the needs of the first few crops Analysis would probably show a considerable quantity in reserve, but it would be in an insoluble form and quite unavailable by the plants without the assistance of some solvent. Even then the amount sc released is by no menas sufficient for the needs of the plants, so that the application of a soluble potash manure is a necessity. There are various forms of potassic manures which it is well to mention as a guide to their use. It is perhaps better here to state the obvious fact that the value of a potassic manure depends on the amount of pure potash it contains. First comes muriate of potash containing about 60 per cent. of pure potash, the others coming in the following order:—Sulphhate of potash, 52 per cent.; "30 percent. potash manure," containing as the name implies, 30 per cent.; and, lastly, kainit with 12i per cent. Now as the object of the farmer in purchasing potash manures is to supply potash to the crops, it follows that with few exceptions he would purchase that which contains the highest percentage of this very necessary fertiliser. Muriate, as I have said, comes first in this respect, but it has this advantage, that owing to the chlorine which is largely present on che drills. Sulphate of potash on the other hand contains practically none—the most being only 1.3, and down to as low as .3 per cent—it is therefore the best all round form in which to use it. Certainly it is the only form in which potash should be supplied to potatoes, carrots, parsnips and beet, as the use of a manure with chlorine in it renders the above roots watery, besides having an injurious effect on the tender rootlets of the potato. Mangels on the other hand are benefited by the application of kainit which has a high percentage, of chlorine in the form of chlorine of sodium, or in other words, common salt. There are also other crops which respond to the application of kainit, such as cabbages and cauliflowers, and among the fruits, peaches, nectarines and apricots, the latter especially calling for the application of salt; Experiments on the stiff soils at Henderson have proved—the fruit growers say—the superiority of kainit over sulphate of potash for peaches, especially the yellow varieties; this I attribute to the high per- , centage of chloride of magnesia which it contains (about 30 per cent., the same quantity as it contains of salt). Such are some of the exceptional cases where the lower grade manure is preferable; but for general purposes the sulphate is perferable, as it is perfectly dry powder, does not cake, and has no injurious effect whatever en machinery. It will do all that muriate, of potash will do without its corrosive effects on metal; it is true that the muriate form has the highest proportion of pure potash, but that is offset by its corrosive action on implements. Experiments made near Hamilton have demonstrated the great value of potash as a turnip manure.; one farmer who had some on hand decided to test it on swedes. He added sulphate of potash to the bone and super, at the rate of 101b to the acre, but after sowing a few acres he found he had more no than he thought, so he increased the quantity to 151b. The potash treated plot was of several acres in extent, and the middle of the paddock was chosen for the experiment, so as to have on each side of the crop untreated with potash. When about to stock the turnips the breaks were fenced across the field so as to include the 101b and 151b potash treated roots, and those which had none. He told me the stock first ate off the 151b lot and then the 101b, and when they were finished they went on to the others. No better test than this could be made short of penning the stock, and feeding each lot separately to the same number of sheep or cattle, but this would involve the trouble of weighing the stock as stores and afterwards when fat, a task too much for any farmer at the price of beef and mutton. The test, however, is conclusive for it shows plainly which roots were the most palatable and it is fair to assume that the food which is eaten with the greatest relish will be the best for fattening. The same gentleman tested sulphate of potash as a top dressing for grass in conjunction with slag with wonderful results; true, he, sowed the fairly heavy amount of half cwt. of the sulphate to the acre, but he said it paid him handsomely. I saw the paddock in the early spring, and the growth of clover was ail that the most exacting could desire. If our dairy farmers knew how exhausting a crop milk is they would realise the necessity of heavy manuring. A cow giving a moderate amount of milk, say, 2000

quarts a year, would send away in that quantity 221b to 261b nitrogen, 101b to 121b phosphoric acid, equal to 21.81b to 20.191b of the best bonedust, and pure potash 101b to 121b, equal to 201b to 241b sulphate of potash. The loss of nitrogen is not so injurious as that of the other two. as clovers are, is suitably manured, always renewing the nitrogen by drawing from the inexhaustable stores in the surrounding air; it is not so, however, in the case of others, as they are minerals and must be replaced artificially. Did space permit I could give very many instances of the extreme value of potash as a manure for every kind of crop, for no plant or tree, from the tiniest blade of grass to the lordly forest tree can thrive without it. More potash is sent away in wool than people suspect. Say a man shears 1000 sheep, each clipping the modest amount of 51b, a total of 50001b, he sends off his farm no less than 20001b of pure potash, which is equivalent to 4001b of sulphate of potash. I may state, in conclusion, that the proper amount of sulphate of potash for potatoes is from 1 cwt to ljcwt per acre.