PHOSPHATIC MANURES

New Zealand Herald, Volume LXIX, Issue 21325, 28 October 1932, Page 3

PHOSPHATIC MANURES

EFFECTS ON GROWTH Phosphates, unlike the nitrogenous fertilisers, increase the proportion of clover in the herbage, and so add greatly to its protein content. This increase is not confined to thp spring months, as happens with nitrogenous fertilisers; it is maintained through the season, and is continued in the next. The gain in protein may be considerable—much greater than the gain in dry matter. In the first year after application water soluble phosphate is most effective, so that superphosphate comes out best. Citric soluble phosphate comes next, hence high soluble basic slag is second. Mineral phosphate and low soluble basic slag are less effective. The value of mineral phosphate as compared with the others changes a good deal according to soil and season. In the drier conditions of Hertfordshire and the Eastern counties, under investigations by the Rothamsted Experimental Station, it came a long way behind high uolublo slag and was very similar to low soluble slag; in the nioister, warmer conditions of Devonshire it acted more like high soluble slag and was much superior to the low soluble slag. In the second year the high soluble basic slag did bettei than superphosphate at several of the centres, both on the hay land and on *he grass repeatedly mown, though it had not then caught, up with superphosphate. At the Devonshire centre mineral phosphate acted as well as high soluble slag, though it was still behind on the two years' programme, but the low soluble slag showed 110 sign of improvement. The experiment is being continued by the Rothamsted authorities to see what happens in the third and fourth years.