FERTILISER UPTAKE MEASURED

Press, Volume XCIV, Issue 28158, 22 December 1956, Page 9

FERTILISER UPTAKE MEASURED

Recent atomic research in Britain has resulted in a rich crop of discoveries in almost every branch of science, including agriculture and horticulture. One of the most promising is the use of radioactive isotopes for tracing the behaviour of fertilisers in plants and soils. Only oxygen and nitrogen among the common fertiliser elements do not possess suitable radioactive isotopes for tracer work. Calcium, potassium, phosphorus and the essential trace elements all have radioactive tracers which have been used to “label” natural and artificial manures.

There have been some interesting results from this work. Often only a very small quantity of applied fertiliser is actually absorbed by plants, while the remainder becomes more or less permanently fixed in the soil. The efficiency of plant uptake is determined by many factors, including the type of fertiliser, density of planting, and so on. Some of the factors influencing phosphate uptake have been studied intensively by tracer methods, and it has been shown that plants take up phosphate from farmyard manure more easily than from superphosphate, and from both far more readily than from the rock phosphate. The maximum efficiency of using phosphates applied to the sc.l is about 35 per cent., but if the phosphate is dissolved in water and sprayed on to the leaves, 95 per cent, is absorbed. This observation suggests that sprayed fertilisers may give quicker returns than those added to the soil.