Spotlight On Tussock Grasslands

Press, Volume CVI, Issue 31221, 19 November 1966, Page 10

Spotlight On Tussock Grasslands

[By a Special Corresponded]

Alexandra in Central Otago was the scene of an important event in New Zealand agricultural history earlier this month. For the first time the New Zealand Grasslands Association devoted its annual conference to the theme of “Grassland Development in Tussock Grasslands and Low Rainfall Areas.”

Scientists, farm advisers and soil conservators from all parts of New Zealand gathered with farmers and runholders from the Mackenzie, Maniototo, Waitaki, Vincent and Lakes counties, as well as those from the more coastal sectors of Canterbury, Otago and Southland, to hear and discuss papers on tussock grassland improvement and utilisation.

Devoting such a meeting to tussock grasslands in a tussock grassland centre, such as Alexandra, constituted a “first” in Grasslands Association history. It was important also for another reason. It marked the acceptance of the tussock grasslands as an integral part of the national grassland improvement scene. For many years tussock grasslands have been looked at askance when it comes to grassland improvement in New Zealand. It has been acknowledged that they could be improved, but most of the pundits have indicated some sort of mystical ecology as the principle of their improvement. As recently as 1951 Bruce Levy had written in "Grasslands of New Zealand”—"on montane tussock country, therefore, return to a grassland cover must depend largely on reconstituing the ecological conditions, such as reducing the rate of stocking and the practice of burning in order to allow successional development back to tussock, or to a modified tussock with herbs, associate grasses ?nd other edible plants.” Sir Bruce Levy was in attendance throughout the Alexandra congress listening and observing, pointing out the ryegrass increasing on stock favoured sites on cloveroversown tussock grassland with less than 20 inches annual rainfall, and suggesting to an irrigation farmer in Ida Valley that his clover needed some phosphate “as it looked pretty sick.” Sir Bruce and other grassland leaders from other parts of the coun-

try had a good opportunity to see how far the Levy-promoted gospel of topdress for clovers and graze for grass applied in the tussock grasslands. It svas a good occasion to hear about some real ecology instead of the more mystical variety that clouded the issue for so many years in the past. Among the many interesting features of the conference were the following: Mr J. M. Hercus, one of the outstanding tussock grassland workers of 10 years ago and now fields superintendent of the Department of Agriculture, Dunedin, gave an excellent account of present farming systems in Central Otago and Mr M. L. Leamy, of the Soil Bureau of the D.5.1.R., presented a straightforward review of the sequences of soils in Central Otago from dry zone to moist highland. On such a sequence Mr T. E. Ludecke (Department of Agriculture) demonstrated the apt use of soil surveys for planning fertiliser use. With Dr. B. P. Molloy, Mr Ludecke gave some indications of progress in sweet brier control by grazing and topdressing management Mr J. A. Douglas (Department of Agriculture) presented a very interesting review of the introduction of grasses experimentally into tussock grassland from about 1910 onwards culminating in his own recent work with cocksfoot introduction by autumn-oversowing even in the driest parts of Central Otago. Mr N. A. Cullen, now Director of the Taieri Agricultural Research Centre, gave a progress report on inoculation and pelleting studies with clover introduction into a wide range of Otago hill country, and Dr. J. G. H. White, of Lincoln College, gave a clear account of experimental work in the Mesopotamia area on lucerne introduction into acid soils.

For his paper in which he gave a complete set of recommendations about pre-treat-ment and post-treatment of oversown tussock grasslands in the Lumsden district of Southland, Mr J. Fitzharris (Department of Agriculture) was awarded the Hurst prize for th: most informative and witty paper presented to the conference. While his recommendations may not apply in all kinds of tussock grasslands as became evident in later discussion, it is obvious that Mr Fitzharris’s forthright approach to pre-burning, to the acquisition of sufficient extra stock and to some kind of mob rotational grazing on topdressed and oversown tussock grassland, will secure a good response not only from soils, plants and animals, but also from the runholders of his district The outstanding work on earthworm introduction into the upland soils of Hindon ■ district in coastal Otago that has been carried on by Mr S. : M. J. Stockdill, of the Departj ment of Agriculture, over i several years, was modestly i but clearly and effectively I presented by Mr Stockdill I himself. The detailed work of Mr Stockdill and associates ; indicated substantial improvejment in D.D.T. and lime dis- : tribution down through the [profile and improvement in 1 water infiltration and in herb- ' age production associated with ; earthworms. It is all the more I remarkable that earthworms [of our grasslands have received so little experimental : study in the past apart from the work of Neilsen at Rukuhia and Sears and Waters at Palmerston North.

Some interest in the problems of winter feed supply

was generated by papers on vacuum silage by Mr R. J. Lancaster from Rukuhia and Mr M. A. Monteath, Department of Agriculture, Gore. But perhaps the most exciting prospects in the winter feed situation were indicated by Dr. P. Barclay and Mr E. Vartha, of the Grasslands Division, D.5.1.R., in initial results from the new tetrapioid westerwolths ryegrass “Grasslands 4707.” Results from Grasslands Division, Lincoln, showed herbage yields of about 12,0001 b of dry matter per acre in 28 weeks from April 1 under a wide range of grazing frequencies. It is startling to find annual herbage production targets for the Manawatu being achieved in about six months of winter in Canterbury. Of interest also was a report from Dr. D. Scott, of the Plant Physiology Division of the D.5.1.R., demonstrating that • net photosynthesis of volunteer species such as sweet vernal and browntop was higher than cocksfoot, ryecorn and the native tussocks when studied in closely controlled conditions. Success was not confined to the scientists or farm advisers. An excellent account of low cost dryland development with lucerne was presented by farmers from the Maniototo. Their long standing success with lucerne in dry land did not apparently diminish their support for irrigation. Irrigation, like tussock country development, can be costly per sheep if there are not sufficient sheep. On one irrigated farm visited in the Ida Valley fewer than four sheep per acre were being carried on land for which the water alone cost 14s per acre. On Mr H. Lyders’s hill country run in White Sow valley near the Maniototo plain about two ewe equivalents to the acre were being carried on the run as a whole on which more than 160 tons of sulphur superphosphate were being applied each year. In spite of low rainfall (17 inches at low altitudes) Mr Lyders’s prospects for fertiliser economy by increased stock numbers and increased fencing look good. Perhaps the session which will call for the longest thought and the strongest action was one in which Dr. K. F, O’Connor, of the Grasslands Division, D.5.1.R., Lincoln, and Mr I. H. Wardell, of Dusky station, presented two challenging papers on tussock grassland improvement and utilisation.

Dr. O’Connor put forward an unusual interpretation as the scientist’s viewpoint. He claimed that it was not the role of the scientist to increase “the factual burden,” but rather “to make general statements of increasing explanatory power and compass that would comprehend particular facts and in a sense annihilate them.” He offered as such a general statement the proposition that the mass flow of cyclic nitrogen through soil, plants and animals governed the total level of production achieved in any life system in any particular place.

He demonstrated in a wide range of tussock grassland conditions that it was not of great importance how much nitrogen was in the soil or how much was added by fixation or from the bag, but rather how much was cycled and how fast. Some of the experimental results briefly reported by Dr O’Connor were quite alarming if considered in the light of professional judgments of 10 to 20 years ago. Moraine pastures, which were producing less than 20001 b of dry matter herbage per acre per year, increased to more than 12,0001 b in four years with annua] topdressing at 3 cwt of suphur super per acre. Hard grazing accelerated the increase and allowed considerable savings in fertiliser. A steepland sour soil under similar treatment increased in herbage production from zero to 90001 b of dry matter per acre per year in four years. With no lime or grass seed costs, this sort of experience gives weight to the claim made by Mr Ludecke at the conference that this is the cheapest kind of land development in New Zealand.

Although Mr Wardell is carrying six ewe equivalents to the acre on the more favoured parts of his Catherine Field property, his own account of his land development experience gives cause for concern. “Each year we grow more and waste more,” he said. It is obvious that the expansion of research in the management and utilisation of improved tussock grasslands on a field scale is urgent. The attitude of one farm developer, Mr R. M. Snow, of Morven Hills, Tarras, seems appropriate in these circumstances—“we will always have new problems. We have to work together to solve them.”