Superphosphate for Wheat

Manawatu Times, Volume 61, Issue 231, 30 September 1936, Page 12

Superphosphate for Wheat

The uso of fertilisers on wheat is increasing rapidly in the South Island and during the 1934-35 season approximately 82 per cent, of the acreage sown was fertilised as compared with only 0(5 per cent, in tho 1928-29 season. The spread of wheat manuring has been stimulated to a large extent by the numerous fertiliser trials conducted by tho Fields Division in every part of tho wheat growing area of tho South Island since 1923. The finding of these trials have been accepted with confidence by the wheat grower since they have been conducted with precision under actual farming conditions in cooperation with well-known wheat growers. The outstanding feature of the Fields Division’s trials was the big increase in yield obtained from the use of lewt. ot superphosphate per aero drilled with ihe seed. The average increase from 1 ewt. Super in 124 experiments was over 4 bushels of wheat per acre and this represented a profit of approximately 300 per cent, on tho outlay for manure. There do not seem to bo auy limitations to the effect of tho above treatment since tho returns were equally consistent- on all soil types irrespective of whether wheat followed wheat or followed grass, and no matter whether the season was good or bad, substantial increases were obtained which justified tho Department's recommendationuse 1 ewt. of Superphosphate with wheat at seeding.

In experiments where other forms of phosphate were compared with superphosphate the latter proved to be the most efficient in all cases. The effect ot mixing lime with super was investigated but positive results from the lime were obtained in only a small proportion of the trials. The success of 1 ewt. superphosphate encouraged the investigators to try out an increased quantity but out of a total of thirty-eight experiments in which 2 ewt. super ft as compared with lewt., the average superiority of tho larger quantity over the smaller was only a quarter of a bushel per acre. From this it was clear that the use of more than 1 ewt. of super per aero could not be recommended except possibly in Marlborough where there threo experiments had given definite returns from the use of 2 ewt. Having such conclusive evidence as tho above farmers can proceed with the manuring of wheat in confidence knowing full well that by using 1 ewt. superphosphate they are generally assured of very profitable returns. Various reasons are occasionally put forward to explain the non-success of auy larger quantity of superphosphate but it would require definite experimental evidence which so far is not forthcoming to justify- the alteration of tho recommendations of the Fields Division. These are so simple and clear-cut that they will appeal to every farmer. For wheat in Canterbury and North Otago use 1 ewt. of superphosphato per acre with tho seed; the uso of a greater quantity as a general recommendation has so far not proved justifiable.