Latest developments in direct drilling

Press, 1 July 1983, Page 17

Latest developments in direct drilling

Recent development of overdrilling and direct drilling technology had concentrated on controlling the depth of seed placement, according to a Massey University researcher.

Dr C. J. Baker of the university’s agricultural mechanisation research Unit was speaking at the 1983 Dairyfarmers Meeting in Palmerston North, presenting a paper resulting from collaborative work with two other members of the research unit’s staff, Dr M. A. Choudhary and Mr S. W. Brown.

Overdrilling for purposes of pasture renovation and improvement had been developed for 30 years, he said. Direct drilling for cash or fodder crop establishment had been practised for 20 years. But these spans of time were as nothing when compared to the thousands of years during which tillage had been practised. Some recent work, he said, had emphasised the development of equipment which would control depth in overdrilling. This depth requirement was particularly important in the placing of small seeds such as legumes. One commercial machine with depth-control wheels on each opener was now available, and another was being developed. In direct drilling the placement of fertiliser close to seeds drilled for cash and fodder crops had resulted in yield increases of 100 per cent or more. This increase was greater than that de-

monstrated by crops in cultivated soil (for reasons that are still unknown), “and it seems to get greater the more frequently the soil is cropped,” Dr Baker said.

He added that there were only about three direct drilling openers in the world that could place fertiliser separately in order to take advantage of this discovery and one was a Massey development which would be released onto the market in limited numbers later this year. Another innovation in the overdrilling of pasture concerned the placement of a banded herbicide to discourage the resident species while the newlydrilled species emerged. This was now being done by rolling the herbicide on to the rubber press wheels of the inverted “T” shaped openers in the latest experimental models. A more efficient coverage resulted than the old spray nozzles which were subject to blockages and which varied the width of the sprayed bands according to the speed of the drill.

Dr Baker covered other aspects of new technology and improvements in techniques of overdrilling and direct drilling. He emphasised the need to create a low-risk, protective slot and discussed ground cover and crop residues as well as problems of soil compaction and wear on openers.

On the economics of overdrilling and direct drilling, he said that university

studies “have put the cost of owning and operating direct drilling equipment (including the need for a larger tractor which does a reduced number of hours per year and therefore costs more per hour to run) at about half the cost of owning and operating comparable cultivation equipment together with a conventional drill.”

He said that if the possible costs of chemicals were added, the total costs would be much the same.

“However, when you include the cost advantages of the six to 10 weeks extra grazing with direct drilling it is not difficult to build a very good economical case for the newer technique. With time you also learn to use rotations that result in less chemical use, and the picture becomes rosier and rosier, and done properly, there will be little or no yield differences either way.”

In summarising, he said: “In all, the rate of development of direct drilling and overdrilling machines in New Zealand has increased in recent years. It will continue to do so and several New Zealand and overseas drills are in the course of development. It is to be hoped that they will encourage farmers to take advantage of a technology which seems to be associated with less and less disadvantages and more and ; more advantages as time goes on.”