Blower Equipment for Hill-country Topdressing

New Zealand Journal of Agriculture, Volume 78, Issue 5, 16 May 1949, Page 452

Blower Equipment for Hill-country Topdressing

By

C. J. HAMBLYN.

Fields Superintendent,

Department of Agriculture, Palmerston North.

AND topdressing of hill country is difficult and A arduous. With modern tractor equipment and where tracks have been bulldozed up the slopes, fertiliser can be got on to the ridges ready for spreading easily enough on most hill country, but spreading still has to be done by hand. It is slow, heavy, costly work, and because of the rough nature of the surface and the hard going across the steeper slopes, the actual spreading is seldom done with any degree of evenness, which is the aim in topdressing on flat land. Though there are hopes that the .aeroplane will provide a solution to the problem of getting fertiliser on to hill country, some recent developments in a technique based on the idea that fertiliser, if sufficiently fine, could be carried over hill country by wind, have reached the stage where extensive practical tests are about to be made.

A ROTARY fan acting as a blower is used to get the fertiliser sufficiently high into the air to be windborne. The fertiliser is fed into the blower from a hopper, passing through the fan to be blown out of a short pipe into the

air. With material as fine as basic slag, and a slight breeze, fertiliser is carried out across the country like a smoke screen and settles down as a fine dusting wherever the dust cloud is carried. The fan is operated at high speed by a light. portable engine or it can be driven from the power take-off of a tractor. By shifting the machine to strategic points along the ridges to make the best of the wind to get the widest possible coverage of the area being topdressed, and taking into account that fertiliser is just as readily carried up the slopes from the floor of gullies by the wind, it is possible to get a surprisingly-good coverage on typical hill country. Demonstrations and trials in the Wellington district with the first machines built for this type of topdressing indicated clearly that the technique has possibilities. . A number of different types of phosphatic fertilisers and lime have been tried and the general opinion is that materials should be sufficiently fine to be carried along by a mild breeze—it appears that they should be as fine as basic slag or North African phosphate. As such fine material is employed, the question arises as to what proportion would be carried away beyond the area it is intended to topdress. The impression given by the early demonstrations is that surprisingly little is carried up in the air currents or carried extreme distances across countrythe problem still seems to be to get the material carried sufficiently far to give a coverage of a typical big hill-country paddock. The really important point at present is that the technique seems to be much more practical than it would at first appear. / The rate of application can be . really fast, trial machines having put out 1 to 11 tons per hour. With experience and judgment and. knowledge of a particular area, operators should be able" to spread the fertiliser to give a satisfactory cover. If 10 tons of fertiliser is to be applied to, say, 100 acres, the type of machine described, used with intelligence, can at least put the fertiliser into the area and spread it over most of the 100 acres. Observations of hand topdressing, particularly contract work, indicate that the, spreading of fertiliser is far from even— goes on in swaths, heavy in some places and light in others, and much of the country gets nothing. As the blower system of topdressing hill country is still' in the development stage, further tests of the results of the work are desirable.