DISTRIBUTION METHODS

Otago Daily Times, Issue 27568, 9 December 1950, Page 4

DISTRIBUTION METHODS

Use Of Blower-type Machines MATERIALS TESTED Increasing use of blower-type fertiliser distributors has been made throughout New Zealand since their development little' more than two years ago, but in order to gather precise information about the efficiency of the machines, the Department of Agriculture carried out trials at Flock House Farm of Instruction. Bulls, early this year. Four makes of machine were tried, and seven materials —serpentine superphosphate, superphosphate, superphos- r phate “ fines,” basic slag; Heskett slag, ground North African phosphate, and ground limestone —were used. The trials showed that to obtain a distribution rate of about 2cwt per acre when using satisfactory material, the blower must operate from a fixed point for two to three minutes. Wind speed and direction, together with the fineness of grinding of the fertiliser, were found to be the main factors affecting distribution. Wind speeds of from 5 to 18 miles an hour were generally considered satisfactory for machine operation, thougn in lighter winds, when the direction tended to be more variable, distribution was improved. In stronger winds,, with more constant direction, the sideways spread of fertiliser sometimes suffered, though the spread along the direction of the wind improved. It was shown that variations in wind speed and direction when operating over a longer period with the lowerpowered machines seemed to result in a' better spread of fertiliser. Analysis indicated that for all materials except Heskett slag a fineness of grinding sufficient to give particles of such size that most of them pass the GO-mesh sieve and a considerable proportion pass the 120-mesh /

sieve is desirable for fertilisers used with blower-type top-dressers. Nevertheless, it was found during the trials that a high proportion of such finelyground material was likely to become air-borne. The area of deposition of relatively coarse materials could be controlled fairly effectively, although the spread was grossly uneven. The spread of finely-ground materials was reasonably good, but there was very little control over the area on which the materials were deposited.