SOIL FOOD AND LUCERNE

Timaru Herald, Volume CXXV, Issue 18630, 28 July 1930, Page 5

SOIL FOOD AND LUCERNE

EFFECTS OF FERTILISERS. Writing on the amount of minerals represented by a crop of a four-ton yield of lucerne hay, Mr Doak. of the Cawthorn Institute, says: “This meant the removal from each acre of lime equivalent to 3801 b carbonate of lime; of phosphoric acid such as would be supplied by 2461 b 44.66, superphosphate; of potash equivalent to 2721 bof sulphate of potash, and 351 b of sulphur. Therefore, to replace the annual removal of mineral contents a lucerne field giving this yield of hay would require a top-dressing of 3icwt of carbonate of lime, 24cwt of superphosphate, iewt of sulphur per acre.” Mr Doak’s analysis showed that the mineral content of lucerne was greatly affected by the seasonal conditions prevailing prior to the examinations made. In autumn, under normal conditions, the lime and phosphate percentages fall off appreciably, the phosphate fall being greater in dry weather. In dry weather, however, the lime precentages of potash and lime present varies inversely. In view of the prevalent idea of the superiority of lucerne as a feed for growing animals and milking cows, analysis of the young growing shoots of lucerne and of average Nelson pasture grasses were made. It was found that the young green growth from the pastures resembled very closely lucerne in its content of crude protein and nitrogen free extractives. The percentage of lime in the lucerne, however, was more than double that in the young pasture, while the lucerne was also superior in sulphur content. On the other hand, the young pasture was four times as rich as the lucerne in chlorine, and also contained more potash and soda. It has usually been considered that young lucerne owes its superiority over grass to its high protein content, but under New Zealand conditions it would appear that the protein content in properly treated grass pasture is remarkably high and that the lead of lucerne in this respect has not been maintained. Mr Doak’s experiments emphasise the fact that the mineral content of the lucerne plot may be profoundly affected by the application of fertilisers and that the weather also exerted considerable influence. The superiority of the lime content of lucerne, however, will always make it yaluable toward improving the lime balance of a ration deficient in this esesntial element of animal nutrition.