FERTILISER PLACEMENT

Press, Volume C, Issue 29625, 22 September 1961, Page 6

FERTILISER PLACEMENT

Efficiency Can Vary

A correspondent requests that I follow-up the information given on fertilisers recently, with details of the efficiency or otherwise of fertiliser “placement.” There has been considerable experiment on this subject in Britain, particularly at Rothamsteaa Experimental Station, but I do not know of any in New Zealand, although it may have been carried out here. Not all ways of mixing fertilisers with the soil are equally efficient, so far as crop response is concerned. In experimental work on potatoes this showed up in a very definite fashion. Four different methods of application were used—broadcast and mixed with the soil before ridging for planting; applied broadcast after ridges were opened for planting; applied in a band at the bottom of the furrow, under the tuber; and applied in two bands, slightly to the sides of the tubers. Their relative efficiencies were: 69 per cent., 100 per cent., 98 and 99 per cent, respectively. In other words, if lOcwf of fertiliser were applied to the acre in the most efficient way—broadcast over the ridges—then it would take 14.5 cwt to the acre to obtain the same erop yield if applied in the least efficient way—mixed with the soil before making ridges for planting. The effectiveness of placement positioning the fertiliser where it can be rapidly used—speaks for itself in this experiment. When seed-raised plants are grown, however, more care is required; the seeds do not have the same resistance to a strong fertiliser application close to them as do potato tubers. If fertiliser is placed too close, emergence of the seedling can be delayed, and the yield actually reduced because of damage to young plants. The method which is recommended for normal garden crops such as peas, beans, carrots, spinach, beets, etc., is called sideband placement—2in to one side of the seed drill, and 3in below the surface. In the home garden this is not too easy to carry out, but on the commercial scale it may be achieved quite easily with combined seed and fertiliser drills.

Why does fertiliser placement work?

Primarily due to less, loss of fertiliser from the soil before it is used by the plant, but also, in the case of potash and phosphorus, due to less "fixation” by the soil, owing to less contact with the soil. Growth starts quickly due to the close proximity of fertiliser, and this early start is of value in competing against weeds and pest and disease. The greatest effectiveness of placement is found in crops which have somewhat restricted root systems.