FERTILISERS AND GRASS.

New Zealand Herald, Volume LXVII, Issue 20537, 11 April 1930, Page 5

FERTILISERS AND GRASS.

EFFECTS ON QUALITY.

Mr. H. V. Garner, M.A., B.Sc., of flic Rotharnstcd Experimental Station, says: "In recent years attention has turned to the quality of pasture grass ill relation to its content of mineral matter. It. has been shown that there is a close connection between the amount of available ash constituents in the herbago and the growth, fertility and general well-being of the grazing stock. Good productive grassland usually contains a higher percentage of minerals than second-rate pasture, which, m its turn, is richer in ash constituents than those poor grazings found in some parts of Britain, and in extensive areas abroad, in which the stock suffer to a greater or less extent from a series of diseases now known to be the result of mineral deficiency. If the shortage is less acute, unthriftiness rather than actual disease may bo the result. The ash constituents most often present in insufficient amounts to meet the need of grazing animals arc lime and phosphoric acid. It might be expected that the richness or otherwise of the soil in the elements of plant food would be reflected in the composition of the plants themselves. This has been shown to be the case. Further, the artificial enrichment of the soil in available plant food, by the use of fertilisers, also affects the amount and composition of the ash of the growing crop. The relationship between the manures and the composition of the ash is well shown. Superphosphate almost doubles the percentage of phosphoric acid in the ash. Tho addition of potash to the phosphate likewise doubles the amount of potash in tho ash. Sulphato of ammonia increases the nitrogen in the hay, and so forth. The most striking changes in the composition of tho ash of grass brought about by fertilisers occur on very poor soils or on soils exceedingly deficient in some particular constituent.

The use of mineral fertilisers on pastures operates in two directions to increase tho mineral content of the herbage. The plants themselves are enriched in ash constituent and the balance of species is shifted in favour of those which can best utilise the added nutrients. Thus legumes follow the application of phosphates, lime and sometimes potash; arid they are on tho wholo richer than tho grasses in mineral matter, particularly in lime, when grown under similar conditions. In addition to considerations of mineral content there is the improvement in quality due to the higher nitrogen content of the leguminous plants. There is also an increase in yield in most cases, which is doubly valuable in conjunction with the better quality.