DIRECT DRILLING OF WHEAT CROPS

Press, Volume CVII, Issue 31542, 2 December 1967, Page 9

DIRECT DRILLING OF WHEAT CROPS

Mr R. Taylor, agricultural research officer of Imperial Chemical Industries (N.Z.), Ltd, is continuing his studies of direct drilling of cereal crops this year, and in the current season there are 24 acres of direct-drilled wheat in his trials in Mid and North Canterbury, compared with four acres last year.

In each ease the crops have been sown following use of Gramoxone (paraquat) to kill existing cover and the seed has subsequently been introduced directly by use of a Duncan 700 Seedliner grain and fertiliser drill fitted with over-drilling tips or by a Howard Rotaseeder, a machine which has been developed for drilling into uncultivated soil.

It is a modified rotavator with a seed box attached. Blades on the rotavator at five-inch centres rotavate a strip about an inch wide, into which the seed is drilled. It has been estimated that the Rotaseeder moves only about 5 per cent of the soil that is shifted by normal methods of cultivation.

The trials are on the properties of Mr W. K. Macdonald at Omihi, where the direct drilling has been done into what was a clover-dominant pasture; on Mr B. Payne’s property at Lincoln, wheye the area treated was also formally clover dominant; at Mr I. Woolley’s at Racecourse Road, Ashburton, where the direct drilling was done into a ryegrass white clover pasture; and at Mr E. Robb’s at Westerfield, where the two areas being used were respectively previously in a yarrowinfested pasture and in a barley crop, after which the bulk of the straw was raked off and burnt

On Mr Woolley’s property the direct drilling has been done across border-dykes and the crop has been irrigated.

Particular aspects of the technique which are being examined are the use of varying rates of nitrogen fertiliser applied in the autumn and spring and also in a

split dressing in autumn and spring, and the use of a selective herbicide for clover suppression—in the main dicamba, but also in combination with MCPA.

In all instances there has been a response to nitrogen applications, which is expected to have an influence on yields. It is uncertain at this stage whether it is necessary to suppress white clover, but if this is necessary then Mr Taylor is interested in determining the best time to do this. He says that there are factors both for and against clover suppression and it is probably necessary to balance the pros and cons. Clover recovers from the initial autumn application of chemical to, kill the grasses and it may be beneficial in suppressing other weeds and acting as a base for a pasture fallowing harvest, but it may suppress yield by competing for light, moisture and nutrients. Certainly, in the case of red clover, Mr Taylor says that suppression is probably necessary. “It is too early yet to draw definite conclusions as to the best method of growing cereals without cultivation,” says Mr Taylor, in reviewing progress of his Investigations to date. “However, the current trials have given a general guide to the factors affecting crop establishment and yield.

“Undoubtedly the major y problem with direct-drilled n cereals has been the removal d of both seed and seedlings by birds soon after drilling. This e can be particularly difficult to c- overcome when drilling comf- paratively small areas. In genl- eral, bird damage in the curfl rent trials has been negligible, > except in the trial at Omihi, which had to be redrilled.

“Bird damage has been largely prevented by drilling seed 1} to 2 inches deep and, where necessary, by rolling after drilling to close the drill slit Chain harrows can be used where soil is loose and friable to help cover the seed, and these were used in the trial at Lincoln.

“Where pasture has been short at the time of spraying both the Duncan drill and the Howard Rotaseeder gave good results. Difficulties when drilling wheat into sprayed barley stubble, however, suggest that where a cereal is to be driUed direct into a cereal

stubble as much straw as possible, particularly loose straw, must be removed or burnt A standing stubble up to about 8 inches high is not likely to cause trouble at the time of drilling.

“From a visual inspection of the trials the Optimum treatment appears to be complete suppression of grasses and partial or complete suppression of clovers in the autumn before drilling and application of nitrogen at the time of drilling (preferably with the seed). Additional nitrogen or a clover suppressant could be applied in the spring if necessary.

“The Duncan drill gave adequate penetration across border-dykes of average height It is apparent that where borders are higher than normal and where they are steep sided seed is either spilt on to the soil surface or drilled too near the surface and subsequently removed by birds.

“The Rotaseeder has given good results and at one site —on Mir Robb’s property—the partial cultivation of the soil by this machine has given a darker wheat crop compered with wheat drilled with the Duncan, suggesting that soil nitrogen has been released to some extent by such cultivation. .

“The costs of the method will depend largely on the quantity of chemical required to give adequate control of

grasses, clovers and other plants. The costs will be highest when direct drilling into pastures and lowest when drilling after a crop—for example when direct drilling into a relatively weed-free cereal stubble. Thus for a valid comparison of costs between direct drilling and cultivation methods it will be necessary to take an average of the costs over a complete rotation of crops and pasture.

“An additional cost with direct drilling, at least initially, will be the use of nitrogenous fertiliser, possibly about 30tb of nitrogen to the acre, which is required under most conditions to give yields equivalent to those following normal cultivation. Further investigation is required to determine to what extent direct drilling methods can affect the farm system and hence costs and returns.”

Where direct drilling was done, into a ryegrass-white clover sward, Mr Taylor said, that costs directly attributable to chemical techniques would include:—

These costs would be reduced by about $5.50 if two pints of Gramoxone was used with no Dicamba, although a selective herbicide might then have to be applied for weed or clover control in the spring. For direct drilling of spring cereals, the rate of Gramoxone might have to be increased to four pints costing an additional $3 an acre.

It was likely that labour requirements could be halved, but otherwise costs for seeds and overheads, etc., would be similar to those with a cultivated crop. Mr Taylor said in this assessment of costs it had been assumed that the farmer owned a suitable drill.

This example gave only a very tentative assessment of costs involved in this method and a more detailed assessment would only be possible when the current trials had been completed. On the property of Mr W. D. Johnstone, also in the Westerfield district, barley has been overdrilled this spring into a border-dyked paddock previously in pasture that had been sprayed. Difficulty was experienced here in negotiating the rather high borders with the Duncan drill, but a particularly good strike has been achieved by this method on the headlands and in the lower half of the paddock.

Per Acre Three pints of Gramoxone (with wetter) .. $10.25 One pint of Dicamba $2.50 Contract spraying .. $1.25 Nitrogen (201b calcium ammonium nitrate which can be applied with seed) .. .. $3.40 Total ... $17.40