THE PASTORAL BASE
"That agriculture, if it is to improve, must take full advantage of the methods and discoveries of those branches of modern botany which specially affect it hardly needs asserting. The yield of meat or butterfat per acre is primarily a matter of the plant covering of the farm."
L Cockayne, The Importance of Plant Ecology with regard to Agriculture. New Zealand Journal of Science & Technology 1918 Vol 1 p.70
Allied with refrigerated sea transport, the technology that can claim to be of greatest significance in New Zealand’s economic development is the growing of grass as pasture for sheep and cattle. Over the years, systematic research, together with an effective dissemination of its findings, has contributed in a variety of ways to the success of this technology. In 1978, 9.2 million hectares, one third of the country’s land area, was improved grassland.
The early pastures in New Zealand were established following forest burns and land clearance. Introduced European grasses thrived on the minerals in ash and in the nutrients released as soil organic matter broke down. In a letter to the London Times in 1882 following the arrival of the refrigerated ship "Dunedin", the New Zealand Agent-General in London asserted that New Zealand had more land laid down in English grasses than all Victoria, New South Wales, Queensland and South Australia put together.
Deterioration of the Pasture
In time however the nutrients, especially nitrogen, became depleted. Deterioration of the pasture took place as the introduced species gave way to less productive grasses and weeds, which could tolerate lower fertility conditions.
Although fertilizers had been used for many years (superphosphate was first manufactured in England in 1839), the idea of applying them to grasslands was still novel when an experiment to test various fertilizers was laid down at Ruakura in 1905; the report stated: "There is a fine green sward on the part treated and the difference can be seen as far as the eye can reach." The Ruakura trials by Cliffton and Aston demonstrated the importance of phosphatic fertilizers for both pasture and crops.
The Wallaceville Laboratory opened in1905 and, subsequently, both there and at Ruakura variety trials were carried out on a range of crops. Following World War 1 came Cawthron’s bequest for the establishment of a regional research organisation in Nelson and among the significant things that were done was pioneer work on the effect of topdressing on yield and composition of pasture. From 1925, A.W. Hudson at Lincoln carried out further experiments on pasture topdressing, clarifying the effects of season and the rate of application of various types of phosphate. He also made significant advances with experimental techniques of measuring pasture growth.
But the important impetus for grassland research came from Cockayne, not Leonard Cockayne, New Zealand’s most famous botanist and the author of the quote at the head of this story but his son Alfred, who was appointed in 1909 as an assistant biologist in the Department of Agriculture and would eventually become Director-General. Using the Journal of Agriculture as his medium, A.H. Cockayne raised the consciousness of New Zealand farmers to the national importance of the grass crop, emphasising the necessity for improving pastures where possible. He foresaw the urgency of establishing a properly equipped plant-breeding station under government control to facilitate this improvement.
Between 1910 and 1920, though slowed somewhat by the First World War, Cockayne continued his grasslands research and his evangelism for the cause. He extended his work to seed testing, publishing accounts of tests for purity, germination, and extraneous seeds, made with samples of cocksfoot, red clover and lucerne, and he made a study of ten million acres of pasture which had been surface sown after the felling and burning of native vegetation.
Researching with Cockayne, also enthusiastic and equally facile with his pen, was E Bruce Levy. From 1920 he too published articles on The Grasslands of New Zealand in the Journal of Agriculture, pointing out the value of mixed pastures containing different grasses which could better sustain uniform growth throughout the year, and the importance of clovers grown in companionship with grasses. He became involved with the problem of the increasing areas of land that were reverting to secondary growth after having been planted with grass following forest burns.
Cockayne’s and Levy’s advocacy of a scheme for fundamental grasslands research finally bore fruit after the visit to New Zealand in 1926 of the famous grasslands scientist, R G Stapleton, Director of the Welsh Plant Breeding Station at Aberystwyth which had been established in 1919. Stapleton emphasised the need for organised research for the improvement of grasslands and told of research being done elsewhere.
The Department of Agriculture finally was persuaded and this led to the establishment of a research station at Palmerston North.
Strain and Breeding are Important
Levy had believed that a programme of improving grasslands should be based on ecological studies as advocated by Dr Leonard Cockayne in his 1918 paper in the New Zealand Journal of Science & Technology but Stapleton insisted that strain and breeding were important as well (ref "Grasslands New Zealand" 3rd edition).
One of the principal objectives of the work at the Palmerston North research station was to find species that could exploit the improved soil conditions achieved by the use of fertilizers. Trial areas containing thousands of rye grass, cocksfoot and clover plants, widely selected from around the country, were established. Growth rates were monitored, total yields determined and behaviour under mowing and stock grazing observed. Of particular interest was the number of seasons the plants persisted before deteriorating. Seed was raised from the best plants, and multiplied until sufficient was available for commercial purposes. In 1930, the Department of Agriculture established a seed certification scheme.
A strain of ryegrass which had been taken from Hawkes Bay pasture was found to have true perennial characteristics. Seed of this strain was multiplied and, helped by the advocacy of Sir Bruce Levy, it became widely utilized on the country’s better pasturelands.
Through breeding from winter producers and spring and summer producers, a strain of white clover was evolved with a long spread of production – from ten to eleven months under North Island conditions.
W.M. Hamilton claimed: "The isolation of New Zealand no 1 White Clover was possibly the greatest single advance made in the recognition of a desirable pasture species – its vigour, high yield, and ability to respond to phosphate topdressing have been outstanding and of the greatest importance in raising pasture yields”.
With the alleviation of mineral deficiencies and appropriate stock management, clovers were found to flourish throughout the country. They provided a high quality feed for livestock and an improved seasonal spread of production. In addition, bacteria associated with the clovers provided nitrogen for the grasslands by fixing atmospheric nitrogen into plant-available forms. (Clover, like peas and soya beans, is a legume. Bacteria from the soil, known as Rhizobia, perform their nitrogen fixing role when enclosed within outgrowths of the legume’s roots called nodules.)
A major breakthrough enabling the wide spread implementation of the pastoral technology was the discovery that a wasting disease in sheep variously known as "bushsickness", (in pumice areas of the North Island), "Morton Mains disease" (in Southland) and "Glenhope ailment" (in Nelson) was due to deficiencies in the diet of trace amounts of cobalt.
B.C. Aston, chief chemist of the Department of Agriculture, sought the cause of bushsickness for many years. He found that the administration of iron compounds, particularly certain deposits of the iron ore limonite, was successful in alleviating the disease, which he attributed to a deficiency in iron. However, not all iron salts were effective and animal physiologists were not satisfied that the iron intake of animals on affected areas was insufficient.
Work on the mineral content of pastures was extended. Two members of the Soil Survey showed that bush sickness was associated with some but not all of the pumice showers concerned in the soil formation of the central volcanic area of the North Island. A major clue came in 1935 when workers on wasting diseases South Australia and Western Australia reported beneficial results from the administration of minute amounts of cobalt to stock. In the same year, spectroscopic examination in England of selected New Zealand soil samples found cobalt and nickel in two healthy soils but could not measure either metal in a soil from Morton Mains. It was found that materials such as the limonite, which had proved effective in combating the disease, contained significantly more cobalt than materials that were ineffective.
Subsequently at Morton Mains and Glenhope and then in the North Island ‘bushsick’ areas, remarkable results were obtained by using cobalt chloride in drench form. Effort was then applied to the determination of the most effective means of application, with saltlicks and mixing with phosphate fertilizer being tried successfully.
The Place of Stock in the Pasture System
It came to be appreciated that the stock itself plays an important part in the pasture system. Stock "fertilizer" returns nitrogen, phosphate, lime and potash to the grassland.
Encouraged by Sir Bruce Levy, now Director of Grasslands Division of DSIR, P.D. Sears, a field ecologist, and R.P. Newbold, a chemist, carried out trials in the early 1940s, publishing their final results in the New Zealand Journal of Science and Technology in December 1948 under the title "The effect of sheep droppings on yield botanical composition and chemical composition of pastures". Sears and Newbold showed that returns of dung and urine increased dry matter production from the pasture by a third.
An Integrated Pastoral System
Thus since the mid 1920’s farmers and technologists (in the guise of professional agriculturalists), have developed a pastoral system based on the association between clovers and grasses consumed in situ by grazing animals. The technology is unique to New Zealand. In no other temperate grasslands is there such a reliance on clover to provide the large inputs of nitrogen for the sustenance of productive pastures.
Nitrogen fertilizer use has thus been minimal. Topdressing has been limited to annual applications of lime and superphosphate and, with heavy concentrations of stock, a high soil fertility has been built up.
The sown grasslands provide the bulk of New Zealand’s production of dairy products and meat. In the 1950s, New Zealand’s time of greatest relative prosperity, grassland products provided an overwhelming proportion of our overseas earnings. In 1953/54 the value of dairy produce, meat and wool exported was 90% of the value of all exports. By 1980, products of the New Zealand pastoral industry were worth three thousand five hundred million dollars in export receipts and although some diversification had taken place into other foodstuffs, fish, forest products and manufactured goods, the pastoral contribution was still about 70% of the total.
The Role of Phosphate
Much has been made of the natural advantage New Zealand enjoys as a result of a temperate climate and adequate rainfall, which allow year round pasture growth. It must not be overlooked that only through the application of science and of phosphates along with other minerals has this advantage been realised and, while the science has been indigenous, the phosphate has been imported. Over the years phosphate has come from thirty different countries in a variety of forms. In the past, imports have included phosphate in the form of basic slag, itself a product of technology, being a by-product of the Bessemer process for steel making. (Belgium was a principal source).
By 1970 basic slag represented only a small portion (5000 tonnes) of the total – and we use none today. The current level of phosphate imports is about one million tonnes per year, valued at $70 million in 1978/79, making it a major import. It is interesting to speculate how much is re-exported in the carcasses of sheep and cattle, and in butter and wool. At the present time the main sources are Australia, Nauru, and the Gilbert and the Ellice Islands (Ocean Island).
The hard high grade rock phosphates from Nauru and Ocean Island are unsuitable for direct application as fertilizer even when finely ground because their insolubility under most soil conditions means that the phophorus is unavailable to plants. New Zealand’s major chemical industry has therefore grown up to carry out conversion of the phosphates to available forms, adding a further link to the chain of dependencies of our farming economy. In the chemical fertilizer industry the two principal processes are the manufacture of sulphuric acid and its use to convert phosphate rock to superphosphate. Sulphuric acid is made from imported sulphur at several works using the "Contact Process". It is then reacted with the insoluble phosphate rock to convert it to the soluble calcium dihydrogen phosphate.
Although the principal features of the technology of high grade pasture production have been understood for several decades, research into grasslands continues. Much of New Zealand’s pastoral land is hill country and it is believed that this would support markedly increased production. New breeds of pasture plants are being tried with a view to increasing productivity and, in particular, white clover breeds which fix nitrogen efficiently in the absence of high phosphorus levels are being sought.
Other breeding trials are being carried out in an attempt to identify plants which are resistant to insect attack; most importantly to attack by the common grass grub which is the most widespread insect pest.
A factor of some significance in view of the 1978 commitment to produce ammonia/urea fertilizers from Maui gas is that the tactical application of nitrogen fertilizer may have value. This is because it is considered that, particularly at cooler times of the year, pasture growth can be restricted due to nitrogen deficiencies.
A number of factors undoubtedly contributed to the increasing value to New Zealand of the pastoral technology in the 1950s and 60s. Favourable economic conditions provided motivation for farmers to increase production; minor soil deficiencies in minerals such as cobalt, copper, molybdenum, selenium and iodine were recognised; production losses from internal parasites in stock were controlled, and new hybrid breeds of sheep were developed.
A complementary New Zealand technology of great importance to pastoral production must not be overlooked. This is aerial topdressing.
Evans, B L: Grassland Research in New Zealand, NZ 1960 Official Yearbook (Appendix)
Levy, E. Bruce, 1970:”Grasslands of New Zealand”, Government Printer Wellington 374 pp
DSIR1978 Grasslands Division – Research Report 1978 – DSIR Information Series No. 132
Sears, P.D. and Newbold, R.P. "The Effect of Sheep Droppings on Yield Botanical Composition, and Chemical Composition of Pasture’; New Zealand Journal Science & Technology June 1942, Part X; Dec 1948 Part II
Smallfield, P.W.,1970, "The Grasslands Revolution in New Zealand", Hodder & Stoughton, 150 pp.
DSIR" Scientific and Industrial Research 1927-38" DSIR Bulletin No. 69, 1938
DSIR "Land alone endures – Land Use and the Role of Research" DSIR Discussion paper No. 3, 1980
Clare, N.T. “The Bush-Sickness Saga” in “New Zealand is Different – Chemical Milestones in New Zealand History” Clerestory Press, 1999
Higgins, D.J., 1999: “The Production of Superphosphate” in “New Zealand is Different – Chemical Milestones in New Zealand History” Clerestory Press.
Walker, T.W. 1999: ”Superphosphate and Biological Nitrogen Fixation”, in “New Zealand is Different – Chemical Milestones in New Zealand History” Clerestory Press.