Oversowing and direct drilling gain ground

Press, Volume CXII, Issue 33034, 29 September 1972, Page 7

Oversowing and direct drilling gain ground

The technique of oversowing or direct drilling, without preparatory cultivation, is apparently taking on. Mr I. E. Woolley, of Direct Drilling Services, Ltd, of Ashburton, who depends on doing it for a living, says that since he first started in 1967 there has been about a 30 per cent increase in the area treated each year and last season he did about 7000 acres.

He has worked in an area from Omihi in North Canterbury to Waimate in South Canterbury.

Pasture renovation forms about half the area covered —about 3500 acres—with, of course, the advantage that the area is only out of use by stock by a matter of weeks. An innovation in this

part of the work has been the application of Gesapon granules with the seed and fertiliser where grass grub is suspected, and Mr Woolley says that it means that oversowing, including the insecticide treatment, can be done for about the same cost as lindane treatment alone. Last season about 1200 acres of brassica crops, including turnips, swedes and chou moellier were direct drilled for winter feed.

These crops are mostly direct drilled after spraying to check competitive cover and the direct drilling and spraying can cost somewhere between about $6.40 and $l4 per acre, depending on the conditions and the amount of spray that has to be used. Spraying is not invariably a prerequisite of oversowing and direct drilling and Mr Woolley says that probably about 30 per cent of his work is done with bare run - out pastures where no preliminary spraying is necessary. Brassica crops, he says, are generally at least as good as Conventionally sown crops or better, and for the last two seasons direct drilled turnip crops

have won the district brassica competitions in the Fairlie area.

Mr Woolley says that from his experience the best brassica crops in the last three seasons have been chou moellier and turnips drilled in October. The balance of the oversowing and direct drilling has been largely involved in sowing of greenfeed cereals and also short rotation grasses into stubbles or into run-out swards.

Quite a lot of work has been done in direct drilling lucerne, stands in the autumn, after the last hay cut has been taken, with greenfeeds or short rotation grasses. Lucerne has also been oversown into old lucerne stands to strengthen them up and lucerne has also been direct drilled Into grass paddocks after spraying.

White clover has also been direct drilled into wheat stubble or burnt stubble in the autumn for specialty clover seed crops. Mr Woolley says that over or direct drilling of cereal crops has only so far been done on a modest scale, in spite of the fact that it has been done very successfully. Three or four years ago following spraying Arawa wheat was direct drilled into border dykes and the resultant crop yielded more than 90 bushels to the acre. There was also a case last season of a part crop direct drilled In a foothill district eutyielding the balance of the crop that had been sown in the normal manner. However, fanners seem reluctant to adopt the technique.

At first there was also some reticence about direct drilling linseed because of

a possible effect of Dicamba used in the pre-drill-ing spray to check clover, on the germination of the linseed seed but trials have shown that this can be done satisfactorily and yields of up to a ton and quarter of linseed have been recorded to the acre. Mr Woolley says that areas with a good summer rainfall are those most favoured for these techniques but they have also been used successfully in dry districts where he says that it is a matter of picking times of the year to take advantage of what rain falls.

Where direct drilling of brassicas and cereals is contemplated he says that it is necessary that the area should be of reasonably good fertility and not heavilv infested with yarrow, cocksfoot or browntop, which cannot be adequately handled by the sprays at present available. Quite a number of areas have had to be turned down for this reason. But pasture renovation and direct drilling of greenfeed cereals can be practised more generally. Where pastures are being renovated it has been found that seeding rates may be reduced to a half of those normally used or even lower, but with brassicas and cereals the sowing rate must be slightly higher than usual. Mr Woolley and his sons began direct drilling and over sowing using a Duncan seedliner drill fitted with oversowing tips and this is still being used partculariy in, say, oversowing or overdrilling lucerne where a degree of cultivation is desirable.

They also use a more recent Duncan development in the triple disc multi seeder with a front skeith that cuts a slot in the ground followed by two skeiths in V formation between which the fertiliser and seed fall into the ground. This machine gives minimum displacement of the turf surface and the Woolleys have used it to oversow a number of golf courses in Christchurch and also many football fields. On golf courses and on park lands they have a modification that controls depth of penetration under varying soil conditions and also helps to close up the slot behind the skeiths so ensuring any surface displacement is even further reduced.

The Woolleys also have two rather heavier machines, made by Imperial Chemical Industries in Britain, that do the same sort of job and these are the mainstays of their agricultural work being suitable for handling a wide range of conditions.

They are now in the process of having a machine built on the basis of their experience to handle all sorts of conditions and also to incorporate 4in row spacings to facilitate quick coverage of the ground following oversowing or direct drilling.

Mr Woolley, incidentally, differentiates between oversowing and direct drilling in saying that oversowing is the applicaton of the same sort of seeds, say grass and clover, to a runout sward, or lucerne into a lucerne stand, while direct drilling is the sowing of a new crop, such as a cereal or a brassica crop.