Still Air Laboratory

Press, Volume CVIII, Issue 31676, 11 May 1968, Page 10

Still Air Laboratory

Use of this shed, which is 75ft square, could lead to the development of improved ground machines for the distribution of fertiliser and to fertiliser mixtures of a particle size that lend themselves to more even distribution.

It has been in the course of erection recently for the New Zeeland Agricultural Engineering Institute kt Lincoln under a special grant made available by the Government late last year. It goes by the name of a “still air laboratory.” Of steel portal frame construction with corrugated iron cladding, it has a completely unobstructed floor space. At either end it has 22ft wide doors intended to take a bulk spreading truck with booms down on either side. Mr E. M. Watson, principal research officer of the institute, said it would be used for the investigation and measurement of the performance of ground fertiliser distributors of various types and designs. The size of the laboratory or shed, he said, was based on measurements of the maximum throw of spreader-type distributors in common use.

To give a standard calibration of the machines under test, Mr Watson said, they would run the length of the building and the evenness of the spread of fertiliser would be measured. The method by which the fertiliser would be collected was one that was used at the National Institute of Agricultural Engineering in England and involved the use of 4ft by Ift trays laid laterally across the floor of the shed at right angles to the direction in which the machine was travelling. Each tray was fitted wtih a 2in grid to reduce the possibility of particles bouncing out again.

but a problem at this stage, which still had to be investigated, was the amount of material which could also bounce into the trays and distort the result.

Mr Watson said it was proposed to carry out a standard test op as many different types of machine as possible in common use in New Zealand. The tests would have to include the various sorts of fertilisers in use and especially the granulated material. This, he said, was part of a national programme in which the relative accuracy of all air and ground spreading methods would be assessed. In addition to the test mentioned, a parallel research programme would be seeking to study tiie important factors affecting the designs of such machines, and such factors as the ballistic properties of the various materials in use would be studied. It was hoped that this programme will lead to development of machines which would give better evenness of spread. A study would also be made of the effect of the composition of fertiliser mixtures and how variations in particle size affected the evenness of spread. Mr Watson said he understood that fertiliser manufacturers were interested in this aspect and it was hoped that this longer term investigation would help manufacturers in producing a more efficient product This could also possibly lead to economies in production but it was not pos-

sible to say at this stage whether the savings would be large or small. Professor J. R. Burton, director of the institute, also mentioned the possible use of a computer programme to simulate the spread of fertiliser from a machine. They would take the characteristics of a particular spreader or spinner and give a range of particle sizes in a hypothetical fertiliser mixture and the computer should then be able to work out the distribution on the ground, in this way It would be possible to try all sorts of distribution of par tide size.

Mr Watson said it was also intended to use the laboratory for investigation and measurement of sprinkler irrigation where the same requirement for still air applied.

At a later date a concrete lined trough would be constructed along the centre of the building as a soil bin, where tillage investigations and measurements could also be made under controlled conditions.

The laboratory has been built by Burnetts Motors with the floor being laid by M Harnett, of Lincoln.

Two other buildings are also in course of construction for the institute. These are a stress analysis laboratory and a workshop and these will be attached to a building which until now has been used as a workshop but which will become a farm machinery project laboratory. These are being erected by Paynter and Hamilton, Ltd.