Major advances in agricultural and horticultural science that contributed to industry development include the following.
In the late 19th century European settlers, encouraged by the government, began to move into the central North Island to clear the bush for farming. But they found that although the land looked fertile and produced great crops and lush grass, sheep and cattle wasted away and eventually died unless they were moved to another area. The settlers called on the government to cure this ‘bush sickness’.
In 1892 Department of Agriculture veterinarians diagnosed it as a form of anaemia and suggested it was caused by a deficiency in the soil, possibly of iron. The Department’s chemist, Bernard Aston, concluded that it was indeed ‘iron starvation’. He developed a cheap, effective remedy: a salt lick incorporating locally-available limonite iron ore. But Aston’s solution didn’t always work. Similar conditions were found at Morton Mains in Southland and Glenhope in Nelson – and also in Australia.
B12 and bush sickness
Ruminant (cud-chewing) animals need cobalt for the production of vitamin B12 by micro-organisms in the gut. This vitamin is then absorbed and stored in the animal’s liver. Vitamin B12 is needed for energy and protein metabolism – so bush sickness is really due to a vitamin B12 deficiency.
Australian scientists found that Aston’s remedy worked on their version of bush sickness, even when they chemically removed all the iron. In 1935 they isolated the effective component – cobalt, a constituent of vitamin B12 required by all mammals. New Zealand scientists related bush sickness to the pumice soils in the North Island. Farmers were able to correct the problem by mixing cobalt into the superphosphate fertiliser they spread on their pastures.
Facial eczema was one of the most serious animal diseases in the northern half of the North Island, and attracted the most research. It seemed likely to be caused by a fungal toxin, but it was only in 1958, after 20 years of fruitless research, that an alert technician mowing experimental plots found spores of a previously unknown fungus which proved to be the source of the toxin. Once this was identified, measures were developed to avoid or prevent the disease.
In 1868 James Little, a farm manager at Corriedale Station in North Otago and later at Allandale in North Canterbury, began a systematic breeding programme to produce a sheep more suited to the pastures of that area. He crossed half-bred sheep and selected and interbred the progeny. His ‘inbred halfbreds’ became known as Corriedales – a very successful multi-purpose breed still used in New Zealand and many other countries.
Three sheep breeds have come from scientific breeding programmes at agricultural colleges. At Massey, Cheviot sheep were crossed with Romneys to produce a breed particularly suited to North Island hill country – the Perendale, named after Geoffrey Peren, professor of agriculture and Massey’s first principal. At Lincoln, Border Leicesters were crossed with Romneys to produce a breed suited to the wetter lowlands and easier hill country – the Coopworth, named after professor of animal husbandry Ian Coop.
The third programme was quite different. Dr F. W. Dry found a genetic factor that produced particularly hairy wool. This was just what carpet manufacturers wanted. It had more spring or resilience than standard wool and would make carpet that didn’t flatten with use. Drysdale sheep now supply speciality carpet wool.
The improvement in dairy productivity during the 20th century was largely due to a scheme that recorded the productivity of individual cows so the best could be selected for breeding. This was introduced in 1922 and operated by the Dairy Board Herd Improvement Council. The artificial insemination service that was subsequently developed enabled genetically better bulls to be used as widely as possible across the national herd.