THE TRUE VALUE OF A FERTILISER

Putaruru Press, Volume VII, Issue 305, 12 September 1929, Page 6

THE TRUE VALUE OF A FERTILISER

PROVIDING AGAINST DRY SPELLS. | TO INCREASE PRODUCTION. Although it is now mid-winter and rainfall is even too abundant, consideration must now be given to the provision of ample pasturage for mid-sum-mer, when short, sharp periods of dry weather dre not infrequent. In this connection it is to be remembered that plants live by drawing from the soil the water containing mineral matter in very dilute solution. This water passes up through the plant to the leaves, where some of the water and the mineral matter is used in the manufacture of starch, sugar and proteins—the foods used by stock. The surplus water not trequired for these purposes passes out of the leaves into the atmosphere. This loss of surplus moisture by the plant is termed transpiration. On a fine day a crop of cabbages will transpire as much as two tons of water per acre. Likewise a pasture in mid-summer transpires into the atmosphere very large amounts of water daily. EXPERIMENTS WITH WHEAT.

Investigators found that the crops varied in the amount of water transpired compared with the amount of dry foodstuff matter manufactured. This lias been termed the transpiration ratio. In the early *9O ’s in South Australia experiments were made with wheat to ascertain the effect of superphosphate on the transpiration ratio. It was found that whereas without superphoo phate, wheat required about 1400 parts of water to make 1 part foodstuff; with superphosphate at the rate of 561 b. per acre the plants required only about 800 parts of water. Thus, with a small amount of superphosphate, wheat was enabled to produce nearly twice as much food as without superphosphate for the same amount of soil water. BUTTERFAT-PRODUCING PASTURES.

The same principle holds good with pastures. Those pastures receiving a dressing of superphosphate will require less water for each pound of dry food matter manufactured by the plants. This can be expressed in another way by saying that the use of superphosphate as a toil-dressing for pastures will result in a greater yield of dry food matter during periods of drought. That this is so was amply demonstrated two seasons ago, when through the somewhat prolonged period of dry weather those pastures ‘top-dressed with superphosphate continued to yield herbage which showed a remarkable capacity for the production of butter-fat.