WHEAT FARMING

Background

Food such as bread and cereals come from wheat. Farmers grow the wheat, and the grains are used to make flour. Flour can be used to make a huge variety of different products, including bread, pasta, muffins, cakes and biscuits, soups and sauces and confectionary.

The wheat plant is tens of thousands of years old. It originates from cultivated strains of grasses. The most productive plants have been selected and bred over centuries by farmers, and more recently, by professional plant breeders. Advances in technology of crop science and production techniques have lead to massive advances in yields and overall grain quality.

A global crop

Wheat is grown world-wide. The main producing areas are Europe, China, USA, Russia, India, Canada, Ukraine, Australia and Argentina. Wheat farming in the UK produces 15–17 million tonnes of wheat each year. Different varieties of wheat are grown depending on the climate and geography of each country. Wheat grows best in dry climates. It needs good, rich soil to produce the largest amount of grain. In Canada, the harsh winters require a fast-growing grain; wheat is sown and matured in about 90 days. Different varieties are used to cope with the dry sun-baked lands of Northern India and parts of Africa.

The structure of wheat

The food value of a wheat plant lies in the rows of starch-filled grains or seeds, called the 'ear', at the top of the plant. Each ear of wheat has about 40 grains. A single grain contains about 20,000 particles of flour. The diagram shows a grain of wheat magnified and cut lengthways through the crease.

A wheat grain is a seed, and each grain of wheat is made up of three distinct parts. There is the coarse outer bran layer then, inside this, there are two main parts. The smaller part is called the germ and the larger part the endosperm. The pericarp (part of the outer bran layer) is a tough skin which protects the inner seed from attack by organisms in the soil. The inner seed coats control the seed’s intake of water. The germ is the embryo plant, with a radicle which can grow into a root system and a plumule which can develop into the stems, leaves and ears of a new wheat plant. The endosperm is the starchy store of food, which the germ will feed on while it is growing.

Different parts of the wheat grain are used to make different types of flour. White flour is made from the endosperm only. Wholemeal flour uses all parts of the grain: the endosperm, the germ and the bran layer. Brown flour contains about 85% of the original grain, with some bran and germ removed.

The wheat farming year

In the UK, wheat is harvested in August, having been planted the previous September. The key farming activities in each season are as follows.

Autumn/Winter: Preparing the land

Farmers plough land to prepare a seed bed for the crops. Ploughing turns over the weeds and debris from the previous crop. These rot underground providing nutrients for the next crop. The extent of cultivation depends on the soil type. For example if the soil is light, the farmer may be able to sow directly into it. However if the soil is heavy, additional cultivation is required to break up the soil

Autumn/Winter: Sowing

Sowing seed is important and can determine a particular crop’s success. It can only be done when the weather and soil conditions are right because the seeds have to be sown at the correct depth and immediately covered. Sowing can take place in the autumn or the spring, but most cereals crops are sown in the autumn. 95% of wheat is sown in the autumn but only 55% of barley.

The correct amount of seed must be drilled evenly across the field. If seed rate is too high, the crop will be too lush and prone to disease; if too low, losses to weather and disease may leave bare patches.

Plant growth during the winter is slow and typically resembles a field of grass.

Spring: The growing season

The plants grow rapidly in the spring. They need sunlight, warmth and water to grow well, and fertilisers are also used. Each wheat plant shoot produces a stem, which grows to about 60cm. The seed head, or 'ear', emerges from the top of the stem in early June.

Wheat disease, insect pests and weed infestations can threaten crop quality and quantity and ultimately the farmer's profitability. The farmer has a number of tools to combat these crop threats; they can be chemical applications — fungicides to control disease caused by fungi, herbicides to keep down weeds, and insecticides to control insect pests — or management techniques designed to minimise risk. Modern farming must balance efficient production of cereals with protection of the environment.

Summer: Harvesting

The wheat ripens, and the nutrients from the plant transfers to the grain in the ear. These grains would form the new wheat plants. Grain is usually harvested between mid-July and September. The climatic pattern of the UK determines harvest progress. Therefore, farmers in the south of England are normally the first to commence the harvest, with harvesting starting later as you travel North.

Combine harvesters cut the crop and then separate the grain from the straw and the chaff. In the combine harvester, the grain is further cleaned over a number of sieves, before being moved to a grain tank. The straw and the ear remains are either chopped and left in the field to provide nutrients for the next crop or left unchopped to be baled for straw. Straw is used to provide winter bedding for livestock and can also be a low value animal feed.

Summer: Storage

After harvest, the grain is kept in special stores free from pests and risks of contamination. Grain storage has to follow strict guidelines to ensure its quality.

This table shows the conditions during one growing year for wheat, and the main farming activities.

Source: George Philip Ltd, Averages for Cambridgeshire

Fertilisers

Fertilisers are substances added to the soil to increase crop yield. They work by providing one or more of the essential ingredients that plants need for growth: nitrogen (N), phosphate (P) and potassium (K). Plants need nutrients as well as carbon dioxide and water for photosynthesis. Plants also need to make proteins and nucleic acids. Macronutrients are needed in relatively large quantities, e.g. nitrogen to make amino acids. Micronutrients are needed in very small amounts. If plants lack these nutrients when they are growing, they show specific deficiency symptoms.

When plants are harvested, the nutrients are removed with them. In a natural ecosystem, the plants would eventually die and decay, and the nutrients would return to the soil. Farmers can use either organic or inorganic fertilisers to maintain productivity. They each have their own advantages and disadvantages:

Fertilisers and the environment

The application of fertilisers in farming is closely monitored and subject to a number of regulations. Incorrect application of nitrogen and phosphorus can have a negative environmental impact. If the nutrients in fertilisers are not taken up by plants, they may be washed out of the soil by rain water and enter streams and rivers – this is called 'leaching'. It may cause a problem called 'eutrophication', which is when freshwater is 'enriched' by nutrients, especially nitrates and phosphates. More nitrates in the stream can increase the growth of algae. The algae make the water cloudy so other plants may die from lack of light. When the algae die, they are decomposed by bacteria. These use up oxygen in the water, which is needed by fish and invertebrates.

The chart shows the amount of different fertilisers used on major crops over a year. Over the past 10 years, the use of nitrogen fertiliser has remained fairly constant. The use of phosphate and potassium fertilisers has reduced, as farmers try to keep costs down and protect the environment.

Wheat disease

The UK climate is ideally suited to producing high cereal/wheat yields, but it also favours diseases, which reduce yield and increase the cost of production for farmers. Wheat diseases can be split into three main categories.

Foliar diseases

• Affect the leaves of a plant.
• Reduces crop yield by reducing the canopy's ability to photosynthesise.
• More important to control disease on the upper three leaves than on the lower leaves, because lower leaves may not contribute significantly to the crop yield.
• Examples include: brown rust, mildew, septoria nodorum, septoria tritici and yellow rust.

Stem-base diseases

• Affect the stem of a plant.
• Reduce crop yield by restricting water and nutrient uptake and may cause lodging.
• Examples include: eyespot, sharp eyespot and fusarium.

Ear diseases

• Affect the ear of the plant, which stores carbohydrate and contributes to photosynthesis.
• Affects quality but have little effect on yield.
• Examples include: sooty moulds, blackpoint, fusarium ear blight, septoria nodorum, yellow rust and mildew.

These diseases can be controlled by the application of fungicides but the farmer must consider whether the disease needs to be controlled, when to spray, how much to spray and which product to apply. Different parts of the UK are more susceptible to disease, depending on weather conditions.

Browse other age groups