Arable farming means growing crops in fields, which have usually been ploughed before planting. Arable crops are generally annual – they need to be replanted each year.
Land is cultivated (prepared by ploughing) in autumn or spring, and the crop is planted. It grows through the spring and summer, and is harvested in late summer or autumn. The land is then cultivated again for another crop or returned to pasture for one or more years.
Early missionaries were the first to grow wheat and oats in New Zealand. In the mid-19th century some North Island Māori communities grew wheat, which they sold to settlers, exported to Sydney, or used themselves.
New Zealand Company settlements, such as Wellington, Nelson and Whanganui, were intended to be based on arable production rather than animal farming. However, at that stage there was a limited export market for crops, but a huge market for animal products – initially for wool and later for meat and dairy production. Cropping remained important in some areas, particularly the Canterbury Plains and North Otago, where summer conditions were ideal for maturing grain crops.
Breaking in land for crops was a laborious job. In North Island bush country, forests were burned or felled, and logs and stumps removed before ploughing could start.
In the South Island grasslands, shrubs, stones and tussock needed to be cleared before ploughing. The vegetation was burnt. In many places the fibrous roots of the tall tussocks had to be dug out – a practice known as spading – before a plough could be used effectively.
Bullocks could be recalcitrant and bullockies were renowned for their colourful language. The bullocky who took Lady Whitmore to Rissington Station, in Hawke’s Bay, was ordered not to swear in front of her. At one point the bullocks came to a complete stop in a river. When all permitted measures failed to move them he appealed to Lady Whitmore: ‘Well, mum, it’s a case of stickin or swearin.’ Faced with the prospect of remaining stuck in the river, she replied, ‘Swear away, Jock.’ At a torrent of familiar words the bullocks got back to their work. 1
The earliest cultivation was done using a single-furrow wooden-framed plough drawn by a bullock team. This required two people – a ‘bullocky’ in charge of the draught animals and a ploughman handling the plough. It was a slow job. Iron ploughs, which were more robust, were introduced. In the 1860s, bullocks were replaced with horse teams, which could be controlled by just the ploughman.
Turnip seed was often sown after the land was first ploughed. Sheep grazed the crop and trampled the ground, helping to break up heavy clods. Next the land was cross-ploughed – a second ploughing at right-angles to the first. It was then cultivated with a harrow – which breaks up the soil into finer clods – and sown in wheat.
Usually, successive cereal crops were grown until the yields dropped to an uneconomic level, due to diminished fertility. Then the land was sown in pasture for animal grazing.
John Grigg of Longbeach in Canterbury was one of the great cropping farmers during the wheat bonanza. At harvest time he needed 70 reaper-binders, 70 wagons, 1,000 horses and 1,000 workers.
In 1867 a trial shipment of wheat and flour was sent from South Canterbury to England. The experiment proved that there was a market for New Zealand grain in Britain.
When wool prices declined in the 1870s, pastoralists on the plains and downlands of Canterbury and Otago turned to large-scale cropping as a source of income. Technological improvements in ploughs and harvesting machinery made this possible.
Iron ploughs imported from Britain and America were an improvement on the earlier wooden ploughs, but they were not robust enough for local conditions.
Local engineering firms soon began to improve on the imported models. Anderson’s foundry made successful colonial ploughs, as did P. & D. Duncan in Christchurch, and Reid & Gray in Dunedin, who both made double-furrow ploughs that became widely used for breaking up tussock grasslands.
In the late 1870s three- and four-furrow ploughs were made, but they did not supplant the two-furrow plough until tractors replaced horse teams.
Ploughmen walked their horses to the field in the morning and back again in the evening. During the day they walked behind their team at work. When using a double-furrow plough the ploughman would work about two acres a day, requiring walking about 20 miles (32 kilometres). Three-furrow ploughs made life much easier because they had a seat.
McCormick’s reaper won the gold medal at the Great Exhibition of 1851 in London, and revolutionised harvesting technology. Before that, crops were mown by hand using either a reaping hook or scythe. The sheaves were then hand tied, gathered and stacked.
In the 1850s reaping machines were imported into Christchurch from England and the US, and in the 1860s Reid & Gray made a reaping machine especially for local conditions.
The reaper-binder, which cuts the crop and ties the sheaves in one operation, was invented in the 1870s. In 1877 Reid & Gray developed a binder that tied sheaves with twine, which was superior to the imported wire binders.
Even after the invention of the reaper-binder, harvesting was a back-breaking job. The machine cut the crop and tied it into sheaves, which were gathered into stooks. Five or six pairs of sheaves were stooked together with the heads upright so that the sap could drain from the stalks. Once dried, they were forked into horse-drawn wagons and taken to the stack. Stacks were built to withstand wind and keep out the rain; building them required considerable expertise.
After being tied, the sheaves were stacked until needed, and then threshed to remove the grain from the straw. Before 1860, when a mechanical threshing machine was invented, the job was done by hand using a tool called a flail.
In 1864 a group of farmers from Timaru imported a traction engine and combine harvester to thresh grain crops. The operator and his machinery travelled from district to district.
Header harvesters first arrived in New Zealand in 1924 and changed the old system completely. These harvesters cut the crop and threshed it in one pass. It left the straw in rows on the ground and took only the grain, with workers bagging it during the process.
In 1958 the first bulk header arrived in Canterbury. It stored the grain while it worked, and then transferred it to bulk trucks for transport to silos. By the end of the 1950s the process of cropping had been completely mechanised.
The main seed crops produced by the New Zealand arable industry in the early 2000s are:
The grain harvested from seed crops has many uses, including milling, malting, manufacturing animal feed and pressing for oil. Milling involves crushing the grain and separating the tough outer husk from the flour. Malting is a process where the grain, usually barley, is germinated, then heated and crushed, before being fermented and made into products such as beer or vinegar.
Some arable crops are grown as forage for grazing animals rather than for grain. These include cereals such as oats and maize, and brassicas like swedes, turnips, rape and kale.
Other arable crops, such as potatoes, carrots and broccoli, are grown as vegetables for human consumption.
In the past, arable crops like sugar beet have been used as biofuels. This application may become more important in the future, with renewed interest in alternative fuels.
In 2002, 42,000 hectares of wheat, 78,000 hectares of barley, 14,200 hectares of maize, 7,400 hectares of oats and 10,900 hectares of peas were grown in New Zealand. There were also 20,000 hectares of pasture seeds and about 10,000 hectares of other crops, mainly vegetable and brassica seeds.
Of the 301,500 tonnes of wheat produced, 46% was used for milling. Total barley production was 441,000 tonnes, with 35,000 tonnes of oats, 149,000 tonnes of maize and 30,000 tonnes of peas.
In 2002, 68% of New Zealand’s arable production land area was in Canterbury, which yielded 90% of the milling wheat and 80% of wheat used as feed. Other wheat-growing regions were Southland, Otago and Manawatū–Wanganui.
Canterbury produced 68% of New Zealand’s barley, but significant volumes were also grown in Southland (10%) and Otago (10%), and also in the Wairarapa and Manawatū.
Oats were grown in Canterbury (60%), Southland (24%) and Otago (9%).
Peas were produced mainly in Canterbury (76%), with smaller volumes coming from Hawke’s Bay, Manawatū–Wanganui, Wellington, Marlborough, Otago and Southland.
In contrast to the other crops, 97% of maize grain was grown in the North Island. Major maize-growing regions were Waikato (25%), Gisborne (19%), Manawatū–Wanganui (16%), Bay of Plenty (14%) and Hawke’s Bay (14%).
In New Zealand arable crops are generally grown on mixed-cropping farms. As well as producing grains, these farms may grow peas, corn, potatoes, beans and carrots, which will be sold to companies for freezing or canning.
Mixed-cropping farms may also have significant areas of pasture, which are initially used to produce herbage seeds, and are then grazed by animals such as sheep, cattle or deer. Forage crops may also be grown, particularly to feed stock in the winter when pasture grows slowly.
Arable farms generally develop a crop rotation system, which:
A major factor determining the crops used in a rotation are the relative economic returns (gross margins) of each crop.
The scientists at Crop & Food Research, a Crown research institute, are recognised worldwide for their research into plant breeding, disease and pest control, development of new agronomic practices and soil science. Some of their research is commissioned by the Foundation for Arable Research, which is primarily funded from a levy on growers.
Although crop rotations vary considerably, a typical rotation might be from pasture to autumn-harvested wheat for milling, followed by barley and then peas. This may be followed by a ryegrass seed crop, spring-feed wheat and then potatoes, before being returned to pasture.
A farm that had more animals might have a shorter arable crop phase, with its main purpose being to improve the pasture crop. For example, a weedy pasture could be cultivated and sown in wheat for animal feed, followed by barley or peas, then a winter-forage brassica crop and back to pasture in the spring.
Traditionally, land that was being converted from pasture into a crop was ploughed, which turned over the top 15 centimetres of soil. The land was left until the existing vegetation had died and then the surface was worked with equipment such as a grubber or set of harrows – tools that are dragged over the soil to break down the clods.
Often this equipment would have a roller or crumbler device that further reduced the size of clods, and compacted and flattened the soil surface to reduce moisture loss. Depending on the structure of the soil, two to four passes over the paddock might be required after ploughing to produce a seedbed with small, even-shaped soil particles.
There is a wide range of modern cultivation practices. For example, using power harrows or rotary hoes, which have moving spikes that are driven by the tractor’s power. These require powerful tractors and are energy-intensive, but may only require one to two passes to produce a suitable seedbed. This can reduce the time between one crop and the next.
Once a suitable seedbed has been produced, the seed is sown at the correct depth using a drill. Fertiliser may also be applied through the drill.
Although seeds should be evenly spaced, this is less important for crops like wheat, barley and peas than for maize and vegetable crops.
After sowing, the soil should be compacted with a roller to ensure good contact of the seed with the soil, and to prevent moisture loss.
About 75% of wheat is sown in autumn (May) and the rest in early spring (August/September). Barley is usually sown in mid-spring (September/October).
Towards the end of the 20th century some farmers began direct drilling, which doesn’t require ploughing. Existing vegetation is sprayed with herbicide and, after it has died, the seed is drilled directly into the soil. This saves cultivation costs and helps retain soil moisture.
Plant breeders select individual plants with desirable characteristics – such as high yield, good quality, and pest or disease resistance – and breed from those plants. After several generations of crossing and selecting these breeding lines, they will be tested in large plot and field trials. Finally, once the breeders are satisfied that their selection has significant advantages, the new cultivar is named and registered with the Plant Variety Rights Office. Some commonly used wheat cultivars are Regency, Domino, Monad, Torlesse and Hussar.
Some direct drills have knife-like T-shaped tines (spikes) to create small slots for the seed and fertiliser, while others create a V-shaped furrow. Rollers then cover the seed and compress the topsoil. As with conventional drilling, this is important to reduce moisture loss.
The cultivation and planting methods used depend on the soil type, the previous crop and the available equipment. Cultivation and drilling account for around 20% of the costs of producing an arable crop. Seed makes up around 10–15% of the costs, so it is important to create the best conditions for seed to grow into productive plants.
Many New Zealand soils do not contain enough phosphorus and sulfur for optimum crop production. These are supplied, along with nitrogen, by applying fertiliser.
Farmers generally test their soils to determine how much fertiliser individual crops will need by taking samples from selected paddocks. A laboratory measures the concentration of elements and makes recommendations about fertiliser.
Superphosphate, often fortified with additional sulfur, is the standard fertiliser used on arable farms.
Nitrogen is supplied through urea or, if more sulfur is required, ammonium sulfate.
Superphosphate may be spread on the soil surface before cultivation or applied through the drill with the seed. Phosphate and sulfur stay in the soil for a relatively long time, so can be applied two to three months before the plants require them. However, nitrogen is easily lost from the soil, so must be applied close to the time the crop needs it. Nitrogen fertiliser is usually spread onto the growing crop, sometimes several times during the season.
In Canterbury, irrigation is essential for high crop yields. In other arable cropping regions, such as Southland, Otago, Manawatū and Whanganui, the spring and summer rainfall is higher and more reliable. Irrigation costs are not usually more than 10% of total production costs.
In mid-Canterbury, low-cost border-dyke systems were the traditional way of irrigating crops and pasture. Their disadvantage is that the amount of water in the borders varies, which may affect the consistency of the crop yield and the time of ripening within a paddock. These have mostly been gradually replaced by spray irrigation systems.
In the early 21st century farmers paid only for resource consents and the cost of watering the crops, not for the water itself. In the future it is likely there will be increasing restrictions on water available for irrigation in Canterbury, and there may be further costs for acquiring water rights and levies on water used.
Water should be applied at the right rate – too much irrigation wastes water and may cause leaching of nutrients, while insufficient water can dramatically reduce crop yield and quality.
Although early research showed that irrigation at two to three critical growth stages would increase yields, later research has shown that yields were improved by having sufficient water, regardless of the growth stage.
Many farmers determine when the crop needs to be watered by first estimating potential evapotranspiration – the loss of water from the soil due to evaporation and crop transpiration. Another method is to measure soil moisture levels with direct techniques, such as calculating the moisture content of a soil sample from its weight before and after oven drying, or indirect techniques, such as using probes or meters.
Soil moisture affects not only crop yield, but also quality. Some crops, such as wheat and peas, may be worth less if the plants lack water while the grain is forming. However, protein content of wheat crops may be reduced if grown in soils that are too wet.
If it is too wet before harvest, some grains may begin to sprout, which also reduces the quality of wheat destined for milling.
Arable crop diseases and pests have primarily been controlled by fungicides and insecticides. However, due to environmental and safety concerns, marketing constraints and resistance to some chemicals, there has been increasing use of other control methods. These include the use of cultivars that are resistant to or tolerant of some diseases and pests, crop rotation and the adjustment of sowing dates. Biological controls are also being investigated for some diseases and pests.
Some of the major diseases that affect wheat are:
Major barley diseases include:
Diseases that can affect peas include:
The main diseases of maize include:
Pests that can damage crops or transmit viruses include:
Arable crops are harvested in New Zealand using combine harvesters, also known as headers.
The time of harvest is determined by the moisture content of the grain, which should usually be below 14%. Most farmers will have a moisture meter to measure small samples of grain from various parts of the paddock.
Most arable crops, particularly cereals, are direct-headed. This means the header first cuts the plants 5–10 centimetres above ground level, and then moves them directly into the machine where they pass through a series of revolving drums and shaking platforms that separate the grain from the straw. The straw is discarded on the ground at the rear of the machine and the grain is held in a hopper in the header until it is transferred to a truck.
The latest combine harvesters can harvest 10 hectares of wheat an hour, or about 100 tonnes. The hopper in the harvester can hold about 8 tonnes of wheat. Usually the grain is fed straight into bulk bins on trucks. Compared to the tough work needing many hands in the late-1800s wheat bonanza, the only workers required for a modern harvest are the harvester operator and a couple of truck drivers.
How the harvested grain is stored depends on its intended market – some is taken directly to the purchasing company, while other crops are held in silos on the farm until they are sold.
If the crop is very weedy it may be necessary to windrow a crop before harvest. This involves cutting it and leaving it to dry on the ground until it can be harvested. If the crop has too much green vegetation it will not separate well inside the header. This generally occurs when the autumn is very wet.
The grain may also need to be dried before storage. Special drying silos blow air through the grain to reduce the moisture content so it can be stored without the seed germinating or micro-organisms growing. Drying facilities on farms are particularly important in Southland, which is wetter than other arable cropping regions.
The straw is a by-product of the harvest. It may be:
Crop yields vary considerably between farms, soil types and seasons, so it is difficult to give average values. Farmers growing wheat for feed expect yields of 10 tonnes of grain per hectare. Milling wheat yields are generally lower, around 6–7 tonnes per hectare, while barley may yield 7–8 tonnes per hectare. Pea yields in New Zealand are around 4–5 tonnes per hectare.
The crops with the highest yield may not necessarily be the most profitable, since the costs of production may affect margins.
New Zealand produces 70% of its cereal requirements and imports the rest. Overall, the production of grains and seed contributed around $380 million to New Zealand's economy in 2002. This equated to about 3% of the total agricultural output.
While arable crops are mostly sold locally, herbage and vegetable seeds are exported (valued at $78 million in 2002).
Cereal-based baking produced from local and imported wheat was worth $130 million in 2002.
Before 1987 the wheat industry was controlled by the Wheat Board, a government marketing authority. Following deregulation, flour mills could buy grain directly from growers, price controls were abolished and import restrictions were liberalised.
Most barley grown in New Zealand is used for malting or making stock feed. Barley exports fluctuate, depending on international prices. Barley marketing has never been regulated in New Zealand, and growers sell directly to domestic and export seed or malting companies.
Oats are grown mainly for human and stock food in domestic markets and are sold to processors either directly or via seed companies.
Fresh garden peas are contracted directly by processors, such as Wattie’s, which have strict quality guidelines. Field peas, which dry in the pod, are used locally for stock food and exported, depending on international supply and demand.
Maize harvested in full leaf, but before it is mature, is used as silage. When matured, the grain is harvested and sold, mainly for animal feed, especially to dairy farmers, or as seed.
The arable processing industry has three main sectors:
There are also companies that specialise in the cleaning, packing and marketing of pasture and vegetable seeds.
There are no collective marketing agencies for the arable industry in New Zealand. Growers must deal with a range of companies, from small firms to large multinational organisations.
Large grain processors in New Zealand include Goodman Fielder and Weston Milling. These companies operate flour mills and animal feed processing companies, and use most of the grain produced in New Zealand.
Animal feed manufacture, particularly for the poultry and pork industries, uses much of the wheat crop. Most of the wheat milled for flour now comes from Australia.
United Wheatgrowers NZ is a committee of 27 wheat growers, aligned with Federated Farmers of New Zealand. It administers a disaster relief insurance scheme funded through a compulsory levy on all grain sold. It also informs wheat growers about available grain contracts.
The New Zealand Grain and Seed Trade Association promotes the development of new varieties, assists with marketing, processing and distribution of seeds and grains, and provides advice and support to the industry. Membership ranges from sole traders to large corporations.
The milling and baking industries also have their own associations.
Acknowledgements to Matthew Cromey, Christine McDonald and Suvi Viljanen-Rollinson
Burnett, P. A. ‘Cereal crop pests.’ In New Zealand pest and beneficial insects. edited by R. R. Scott, 153–167. Lincoln: Lincoln University College of Agriculture, 1984.
Claridge, J. H. Arable farm crops of New Zealand. Wellington: Department of Scientific and Industrial Research, A. H. & A. W. Reed, 1972.
Jermyn, W. A., and G. S. Wratt, eds. Peas: management for quality. Lincoln: Agronomy Society of New Zealand, 1987.
Pea disease identification guide. Christchurch: New Zealand Institute for Crop & Food Research, 1995.
Wright, G. M., and R. B. Wynn-Williams, eds. Barley: production and marketing. Lincoln: Agronomy Society of New Zealand, South Island Barley Society, 1983.