Direct drilling gives better results on station near Fairlie

Press, 4 December 1981, Page 17

Direct drilling gives better results on station near Fairlie

Direct' drilling or conservation tillage is playing an important part in the development of the 9148 hectare Clayton station between the headwaters of the Orari and Opuha Rivers, about 23 kilometres from Fairlie in South Canterbury. Mr W. A. (Andrew) Orbell told the conservation tillage seminar in Christchurch last week that the present policy on the property was that any country which could be negotiated by the four-wheel drive tractor was to be developed by direct drilling. He said that stock increases on direct drilled country to date ranged from about two stock units per hectare or less to six stock units per hectare and an even greater improvement was anticipated on the lower blocks in the better rainfall areas. Even when allowing for oversowing being done generally at higher altitudes, he said that direct drilling was providing higher stock increases on the station. For a similar response, it was. observed that direct drilling was up to three years faster than oversowing. There was also a more even spread of seed and fertiliser than from aerial oversowing. On current costs the initial increase in carrying capacity from direct drilling cost $55 per stock unit whereas oversowing was costing $67 per stock unit increase. Clayton consists of alluvial flats at 500 to 600 metres, with tussock hill country rising to 1100 metres adjacent to the flats, and a smaller area of steep hill country rising to 1500 metres. Rainfall varies from 750 to 1500

millimetres over the station and during most winters 15 centimetres of snow can remain on the flats for one to two months. Grass growth starts in late September or early October. At present there are 650 ha in cultivated paddocks, 715 ha in direct drilled blocks, 1825 ha oversown and 5473 ha in the native. . The station carries a Corriedale ewe flock with replacements being bred on the property' and all lambs are fattened. There is also a Hereford herd with replacements and all calves are carried through to the spring sales. There is also a small deer unit. Before it was purchased by the Orbell family in 1964 it was run .as an extensive grazing property carrying 7500 stock units. By this year the tally had increased about three times to 22,100 stock units and further increases are anticipated. Until 1977 development was concentrated on the flats. At that stage about half of the alluvial flats (600 ha — comprising the better soils — had been developed by the plough by way of a winter feed-grain-new grass rotation. However, two or three windblown paddocks demonstrated the risk of cultivated paddocks exposed to the north west wind. An intensive fencing programme was also undertaken in conjunction with a Catchment Board run programme, which involved retiring 485 hectares from grazing, and a series of tracks were also established on the hill country. Although present develop-

ment was centred on the hill country, Mr Orbell said that paddocks on the flats remained important for growing winter feed crops, haymaking and stock fattening. In late 1977. in co-opera-tion with P. and D. Duncan, Ltd, a triple disc MultiSeeder drill waS brought to the property for testing. Mr Orbell said he was very sceptical about the idea initially and the drill had come merely to test its ability to survive mechanically under tough conditions. In the summer of 1977-78 the first 40ha had been drilled in a. lower rainfall, Hieracium-invaded and very stony block with a mixture of white and red clover and cocksfoot with sulphur superphosphate. The seed was not coated or inoculated but by the following autumn results were encouraging enough to proceed, with a further 60 hectares. In the autumn of 1979 320 hectares were direct drilled and in the autumn of last year another 200 hectares, with 60 hectares being on steep hill country. This had been successful and led to the present policy that any country that could be negotiated by a four-wheel drive tractor was to be direct drilled. Where a block was to be developed by direct drilling or oversowing, he said that it was mob stocked with sheep and cattle during the previous spring and summer to remove trash and reduce competition. The drilling was started in the early autumn, being the responsibility of the tractor driver after finishing the hay making. Where a large block was to be drilled, work might have to start in the late summer. So far the drill had often started at the bottom of a block working up as high as the tractor driver’s skill allowed. Above this level was generally oversown in the following spring. The topography of the blocks often allowed subdivisional fences to be erected across the block between direct drilling and oversowing. The development planned for a more distant block next March would see the fourwheel drive tractor drilling the top of the more gentle' ridges and the following spring the steeper lower country would be oversown. The seed mixture used per hectare at present consisted of 2.2 kilograms of ryegrass, I.lkg cocksfoot, I.lkg Alsyke and 3.3 kg white clover. The clovers were molybdenum coated and inoculated and the cocksfoot was also coated. The fertiliser used included 250 kilograms per hectare of molybdenum sulphur superphosphate extra drilled in the autumn and 500 kilograms per hectare of Flowmaster sulphur superphosphate applied from the air in the spring. Fencing of the development blocks was generally done during the winter following drilling. All of the autumn-drilled blocks were shut up until the following summer. While this provided a visually impressive bulk of feed, Mr Orbell said he was convinced that this assisted establishment and future production. This policy also dovetailed well into the station’s summer grazing management. It had been the practice to wean lambs onto the direct drilled blocks in mid January. As well as the pastures being parasite-free, the clover dominance provided excellent fattening feed. Mr Orbell said that while basically the drill was suited to the job some parts had not stood up to the rough conditions and as a result several parts had been modified. . .

Fertiliser quality and consistency was another problem . Most of the damage had been done initially when working over large rocks where the operator was lifting the drill. Now the drill was kept in its working position regardless of the terrain and the ground speed modified. Higher initial rates of fertiliser had been justified when comparison was made with results from low phosphate rates. Soil tests also confirmed the benefit of the high rates. The use of sulphur superphosphate extra was also shown by soil tests to be quickly raising sulphur to acceptable levels and it was anticipated that adequate sulphur levels would be maintained with use of sulphur superphosphate and then straight superphosphate for maintenance applications. Molybdenum superphosphate was used because of the known response to molybdenum in the area. Alsyke clover was included in the seed mixture for initial bulk and was expected to remain an important species on the colder wetter blocks, but it disappeared from the dry sites. Ryegrass was sown at a full pasture rate but was not very evident in the early years. Its continued use was, however, based on any grass establishing providing a selfseeding source and older oversown areas on the station now showing strong ryegrass and cocksfoot growth. In 1977 there were 14,000 stock units on Clayton and by this year they had increased to 22,100. During the autumn this year a new three-year development programme began including direct drilling, oversowing, fencing, track construction and provision of a second airstrip. The stock target for June, 1983, was now 25,000 stock units and it was expected that development from the programme would not come on stream until at least 1984/85 when the target was for 27,000 stock units. Discussing problems, Mr Orbell said that effective establishment of ryegrass caused some concern, but this might be only through impatience when observing grass establishment in older oversown pastures. New grasses, such as Roa cocksfoot, would be watched with interest and especially species which would enable good quality standing feed to be carried into late winter to assist rotational grazing. The high cost of superphosphate was also causing concern and this was the reason for the “high rate applied less often’’ approach. High analysis fertilisers were being watched closely and D.A.P. fertiliser might be applied from the air for the second capital fertiliser application. Fencing to date had been conventional post and wire but now that most main blocks had been fenced, electric fencing for subdivision was beginning to appear inevitable. In 1979, Mr Orbell said that they had moved from conventional cultivation for swedes to direct drilling for winter feed. This policy had been' modified to the extent that grass was included in the seed mixture so that new pasture and winter feed were established in the one operation, but lately there had been a change back to a conventional cultivation programme. One of the reasons for this was that conventional cultivation was slightly cheaper, and over the large area of winter feed grown this became significant.