GORGING SOILS.

Otago Daily Times, Issue 20964, 1 March 1930, Page 7

GORGING SOILS.

AND SOME OTHER ERRORS CONCERNING MANURES AND FERTILISERS.

There was a time when animal manure was plentiful, and when the number of ■well-cultivated gardens was small by comparison with the present day, that some ardent enthusiasts gorged their garden soil with natural manure to such an extent that it became sick and unhealthy. The present day scarcity of manure has effectively checked that procedure—except where live-stock is kept. In the laudable endeavour to ensure that substitutes for natural manure shall be used we have induced a great many people to dope their ground and their plants with all sorts of strange chemicals, and, because their nature is insufficiently understood, the effect upon the soil and its occupants is frequently the reverse of that desired and expected. Using chemicals on soil without a scientific knowledge of chemistry is very much on a par with administering drugs and physics without the knowledge of a doctor. Compound chemical manures, which bear well-known names and have stood the test of time, are worthy of confidence. They are mixed scientifically, the ingredients are ground and prepared by up-to-date machinery, and are tested for purity and strength by qualified chemists, who are able, with their knowledge and facilities, to ensure a well-balanced compound which will flourish soil and feed plants in a satisfactory manner.

The greatest mischief is caused by the excessive use of one kind of chemical. A soil may be deficient in nitrates, another in phosphates, or in potash. Perhaps in the first case a dressius of nitrate of soda or of sulphate of am monia is given, and as a result crops are greatly improved. The mistake is made when, as a result of the encouragement thus given, the owner decides to go on giving nitrate of soda or sulphate of ammonia season after season. Before long the soil will become satiated, and there will be insufficient of other essential elements to combine with the abundance of nitrates. The results arc similarly bad when either sulphate of potash or superphosphate of lime are given repeatedly. Such one-sided feeding upsets the balance of plant foods in the soil.

Almost, if not quite as bad, is the blind effort to ensure that the land obtains what it needs by giving a bit of everything possible. We Save known instances where a plot of land has been dosed with sulphates of ammonia and potash, superphosphate of lime, basic slag, kainit, bonemeal, and guano, and, in addition to all, has been heavily dressed with fresh slaked lime. The result of such haphazard use of soil nourishment is about as beneficial to the soil as would be a mixture of fish, pork, ROrridge, treacle pudding, and cheese to a sick patient. To begin with, it is needlessly extravagant, for one thing is calculated to nullify the capabilities of another. It is detrimental because there is bound be unequal capacity for proper assimilation of the various chemicals by the soil. For instance, kainit provides potash as well as the sulphate of potash, and there will be some more potash in the guano. Superphosphate, basic slag and bonemeal all contain phosphates, and the guano again supplies more. The dressing of lime renders waste some of the most valuable of the foods mentioned. Sulphate of ammonia and sulphate of potash are both rapid in action, but to dress the soil, immediately after their application, with lime will so hasten their solution, that a few rains will wash therif away before the plants can utilise them. Again, bonemeal is one of the slowest of fertilisers in action, but if lime is brought into contact with bonemeal, it arrests the process of decomposition, causing the bonemeal to be dormant for a very long period, during which, it is as useless to plants as shingle would be. Lime is inline- ely serviceable to soil and to plants, but it is a great pity that this fact has led many well-mean-ing folk to preach lime, lime, lime!! as though it is impossible to go wrong with it and impossible to use too much of it. One can do both just as easily as one can work mischief by using a good physic at the wrong time or giving an overdose to a weak patient. ” We have no intention of disparaging lime or denying its great horticultural value, but our desire is to point out that even =o useful a commodity must be used will •■--Hi" ,; n dgment. It is far better to lime ground at one time, and manure it at another. A plot of ground m- be dug arid limed durin" late summer or early autumn. The lime will have lost its attacking powers by late autumn or early winter. Manure, bonemeal, or basic slag will then he free from harm if dug in. Alternatively, one may trench a plot in the autumn, digging in manure, bonemeal, basic sla°, or kainit. That plot should not be limed before the following August or Septcm her.

To condense as much of this subject as possible into a nu' bell, the safest plan is to use a com—-d fertiliser as the manufacturers advise it should be used, and refrain from using anythin" else at the time. Use natural products" such as —o. bonemeal, hoof and horn shavings, or fish-meal one at a time, and change the kind at each dressing. Use lime when it is ascertain-d that it is necessary, but not when manurin".— Amateur Gardenin". °