MANURES.

New Zealand Mail, Issue 1157, 4 May 1894, Page 5

MANURES.

THEIR FUNCTIONS, COMPOSITION AND VALUATION. Briefly stated, the following are the functions of manure :— (a) In many cases manures improve the physical and mechanical condttion and the texturo of the soils to which they are applied. Thus lime when applied to sour land decomposes, and therefore renders harmless the sour organic acids, whose presence in the soil is the cause of the sour or acid condition of the land. When farmyard manure is applied to land the texture and physical condition of the soil is much improved by the organic matter of which this manure is largely composed. ( b) In many cases manures act on plant food already present in the soil, and convert this plant food into such a condition that it can be absorbed by the roots of plants. The manorial value of lime is due principally to the action of this manure on the food of plants already present in the soil, (c) The moat important function of manures is to supply plant food necessary for the growth of the crop which is deficient in the soil. The necessary constitutents of plant food that are generally deficient in soils are uitrogen, phosphoric acid, and potash. Nitrogen occurs in manures as [a) Nitrates e.g .. nitrate of soda. ( b) Ammonia salts, e.g., sulphate of ammonia. (c) Organic nitrogen, e.g., dred blood.

Nitrogen as nitrates is immediately available at plant food. Nitrogen as ammonia salts soon becomes available.

Nitrogen as organic nitrogen is much more slowly a rail able. Phosphoric acid combine! vrith lime is generally present in manures as : (a) Insoluble phosphate of lime, e.g., bone meal and basic shg # ( b) Soluble phosphate of lime, e.g., superphosphates and dissolved bones.

Insoluble phosphate of lime is converted into soluble or superphosphate by treating it with sulphuric acid. Soluble phosphates are generally more active than insoluble phosphates in promoting plant growth. Potash is the valuable ingredient in kainit and muriate of potash. Potash has generally a better effect on light than on heavy soils.

Superphosphate and nitrate of soda should not be mixed, or if mixed must be sown immediately. f J bis also applies to the mixing of basic slag and sulphate of ammonia.

Artificial manures should be pur* enased on a guaranteed analysis, and tho source from which the fertilizing ingredients of the manure are derived should be stated. This precaution is especially necessary in purchasing bone or mixed manures. The percentage of nitrogen in a manure should be stated in its equivalent of ammonia, that of insoluble phosphoric acid as phosphate of lime, soluble phosphoric acid as phosphate of lime, and that of potash salts in their equivalent of potash.

Artificial manures are valued according to the quantities of nitrogen, soluble phosphate of lime, insoluble phosphate of lime and potash they contain, and are generally valued on the unit system. The amount of a unit taken to be 1 per cent, of a ton. Thus 1 ton of nitrate of soda containing nitrogen equal to 19 per cent, of ammonia is said to contain 19 units of ammonia.

Farmyard manure coutains all the ingredients of plant food. This manure is exceedingly variable in quality, as the quality varies with the nature of the food given to the animal, the nature and amount of the litter used, the method by which the manure is produced, and its treatment from the time of production until it is applied to the land.

Amount or Manuriae Increments Generally Present in the More Important Manures.

The manures mentioned in the above table cun always be purchased at a much cheaper rate than special manures, such as “grass manures," “cereal manure," “ turnip raanure/’&c. Nitrate of soda should not be applied to any crop until that crop has reached an active stage of growth. Sulphate of ammonia is generally applied along with the seed of any crop. The phosphatic manures, bones, superphosphate, basic slag, &c , are not like nitrogenous manures, liable to be lost from the soil, henco they may be applied for some time before the growth of a crop. As a rule basic slag should be applied to soils rich in organic matter and poor in lime. Superphosphate generally gives a better result on harder land. In the case of basic slag it is a distinct advantage to apply it in the Autumn or early winter for a crop to be grown during the following season. Tho qualities of this manure, which contains phosphoric acid equal to 37 per cent, or more of phosphate of lime, give the best results, and this manure should be ground fine enough to allow 85 per cent of it to pass through a No. 100 wire mesh. Superphosphate should always be in a dry powdery condition and not pasty, as if so it is impossible to distribute it evenly in the soil. It is probably desirable to apply potash manures iu the autumn or early winter. When artificial manures are applied some time before the growth of a crop care must be taken that they a-e not buried,, too deeply. —Mark Lane Express,

Amount Per Cent. OF "" Nitrogen equal to Ammonia Phospl Lit Sol u d e. rate of no. Insoluble. "3 A 2 v o o 2 to Nitrate of Sod* (95 per c-nt. purl y) 19 , - „ — Sulphate of ammonia (U7 per cent, purity) 24 — — Nitrate of potash (85 per cent, purity) .. 14 — — 40 Dried blood .. 15 — — — Horn dust 14 — — — Bene meal 4—6 — 44-65 — Steamed boUc flour .. 1-2 — 56 — . ! 5 Dissolved bones 3\> 16-30 10-14 — Superphosphate (high clas.>) , 35—40 Superphosphate (low class) .. _ 20 28 37-42 Basic slag(best quality) — — — K.iinit —- — — 12 Muriate of potash (80 percent) tI - . _ 5) Sulphate of potash (50 percent) _ 27*5 Peruvian guano (low class) 3-5 3»— 5 0 1—3 Iclnboe gumo 10-10 18--3J 2 Fi-.li guano 7—12 17—3S 1 “ —