Wheat

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Wheat (Triticum) is a type of grass that has edible seeds called cereal grains. Wheat is a staple food item for people all over the world and is the second most widely grown crop, just after maize. Wheat is most commonly ground into a flour that is used for baking bread, biscuits, pastries and pizza. It is also used to create breakfast cereals, to make pasta, and it can even be used to make alcoholic beverages such as beer and vodka.

The part of the wheat plant that houses the edible seeds is called the spike. Each spike has a number of spikelets that contain the cereal grain that we use as food sources for humans and animals.

Modern farmers use combine harvesters to cut (harvest) the stalks of wheat and to separate (thresh) the edible parts (grain) and the inedible parts (chaff). Other grains similar to wheat include barley, oats, millet and quinoa.

If you suffer from a wheat allergy, it may be difficult to avoid wheat because it is used in many baked goods, spices, sauce mixes, breakfast cereals and even as a thickener in commercially produced yoghurts.

Maize

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Maize (Zea mays) also commonly known as corn, is an essential part of the diets of people all over the world. It can be cooked, ground into a flour and it can even become popcorn. Maize is also commonly used to feed livestock, and it can be processed to create fuel (ethanol) and food products such as corn syrup, which is frequently used to sweeten mass-produced food items. Maize is an annual crop. Each cob holds around 800 corn seeds in 16 rows.

Maize is usually harvested by a machine called a combine harvester (see below). This machine uses a combination of wheels, blades and arms to cut (reap) the plants, separate (thresh) the edible parts (the grain) from the inedible part (the chaff) and blow (winnow) the chaff out through a pipe.

The five countries that produce the most maize every year are the United States of America, China, Brazil, Argentina and Ukraine. Production is measured in millions of tons with the US producing over 392.5 million tons of maize every year.

Insects

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Insects are small air-breathing arthropods (such as ants, beetles, butterflies, bees) with a three-part body (head, thorax and abdomen), three pairs of jointed legs, typically one or two pairs of wings, compound eyes and two antennae.

Insects are the most diverse group of animals; they include more than a million described species and represent more than half of all known living organisms and over 90% of the animal life forms on Earth. Insects are found in nearly all land environments, but only a few species reside in the oceans. Insects perform a vital role in supporting other life forms and ecosystems; pollination, soil aeration, processing of nutrients and as part of the overall food chain.

Entomology is the study of insects and their relationship to humans, the environment, and other organisms. Entomologists contribute to such diverse fields as agriculture, chemistry, biology, human/animal health, molecular science, and even criminology and forensics.

Plant-parasitic nematode feeding types.

Nematology

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Nematodes, also known as roundworms and eelworms, are one of the most diverse and abundant groups of animals on earth. They are found on every continent and in almost every habitat known to man. Nematodes in the soil are microscopic organisms and can very rarely be seen with the naked eye. There are many different kinds of nematodes and they are divided into groups based on what they eat. Herbivorous nematodes (plant-parasitic nematodes), feed on all different parts of a plant. These nematodes are sometimes referred to as the bad nematodes because they can cause damage to agricultural crops and they make it difficult to grow the food we eat.

But there are also beneficial nematodes, the so called good guys, which can be beneficial to humans because they are essential for soil health. These nematodes are also divided into different groups. Bacterivores (nematodes that eat bacteria), fungivores (nematodes that eat fungi), predators (nematodes that eat other microscopic animals including other nematodes) and omnivores (nematodes that eat plants and animals). These nematodes play an essential role in the soil food web because not only do they eat the other organisms in the soil, but they are also food for many of the other animals also found in the soil. Nematodes are also important in nutrient cycling in the soil, enabling plants to take up nutrients and ensuring plant growth. In the soil environment there are millions of nematodes from all the different feeding groups.

Head stationary despite body movement

Chicken

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Chickens (Gallus gallus domesticus) are domesticated birds that are kept as livestock. Humans consume chicken meat as well as eggs as a common part of their diet. Chickens are the most widely kept domestic birds with scientists estimating that there are over 23 billion chickens in existence.

Hens (female chickens usually over a year old) lay a clutch of around 10-12 eggs (one egg a day over the course of around two weeks). The hen incubates the eggs by keeping them warm and safe until they hatch, about 21 days later. Chicken are omnivorous birds.

Chickens can keep their heads stable even when their bodies are moving. They have evolved this ability because their eyes cannot remain fixed on an object in front of them while they are moving, so instead, they must keep their heads still to keep the focus on an object. Although they have functional wings, they cannot fly for more than a few seconds at a time.

Chickens have a lifespan of around 5 -10 years. Through DNA studies, some scientists believe that they are the closest living relative to the Tyrannosaurus Rex.

Chicken feathers are commonly used to create bedding items such as pillows and duvets. and also used to stuff upholstery,

Cattle

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Cattle (Bos taurus) are livestock animals that are commonly raised for their meat, for milk (from cows) and for their hides which are used to make leather items. Cattle are common all over the world, and scientists estimate that there are over 1.5 billion heads of cattle in existence.

Cattle belong to the group of animals called ruminants . They have a fascinating digestive system that is adapted to take nutrients from grass, which does not have a high nutritional value. Their stomachs have four compartments, and when grazing, cattle can regurgitate their food (which is now called cud) to chew it down into smaller pieces.

Some breeds of cows are kept specifically for their ability to produce milk that humans can consume, rather than for meat production. The most well-known dairy breeds are Holstein Friesian, Jersey and Ayrshire breeds. Special machines have been designed to automate the laborious milking process.

Typically cattle have a lifespan of 18 to 22 years and weigh around 1 100 kg.

Olives

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Olives (Olea europaea) are fruit from olive trees that originated in the Mediterranean region. Olives have been grown by humans as a food source since 3 000 BC, but wild olives had been a part of the human diet since the early Bronze age about 5 000 to 6 000 years ago. There are more than 100 types of olives.

Olives can also be processed into olive oil, and various parts of the olive fruit are used to produce cosmetic products such as body lotions, shampoos and makeup for human use. The fresh leaves of olive trees can also be used as an additional source of nutrients in animal fodder.

Olives were traditionally harvested by hand; farmers often lay down nets or tarp to catch the falling olives to make gathering them easier. Modern olive farmers often use machines that have special attachments that surround the tree and then hold the trunk of the tree and shake the fruit loose.

Black olives are just ripe green olives. Olive oil is made from perfectly ripe olives (from both the flesh and stones or pits of the olive) that are ground to a paste. Olive oil manufacturers use different methods to extract the oil from the paste including soaking the paste in water to let the oil float to the top, or by spinning the paste in drums to remove the oil.

Soil

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Soil is the loose surface material consisting of inorganic particles, organic matter, water and air that covers most of the land surface. Soil retains moisture and provides structural support for roots and nutrients for vegetation, forests, grass plains and crops.

Soils vary significantly in their chemical and physical properties and texture. Inorganic material is the major component of most soils. It consists mainly of mineral particles with specific physical and chemical properties which vary depending on the parent material and conditions (climate, topography) under which the soil was formed. The texture of the soil is mainly determined by the relative proportions of inorganic particles of different sizes.

The organic material is concentrated in the near-surface layers of soil, being a product of local vegetation and animal and insect activity. Soils also host a hidden animal kingdom whose presence is vital to maintaining the health of the soil. Worms and insects produce most of the humus found in the soil through the incomplete digestion of organic matter.

Processes such as leaching, weathering and microbial activity combine to make a whole range of different soil types, each of which has particular strengths and weaknesses for agricultural production.

Plants

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Plants form one of the six big groups or kingdoms of living things. They have complex cells, make their own food and, usually, they cannot move (except for growing). Plants include familiar types such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The ornate members are called flowers. The scientific study of plants is called botany and has identified about 350,000 species of plants. Fungi and non-green algae are not classified as plants.

How plants grow
Most plants have stems that grow into the air and roots that grow in the ground. Some float on water. The root part absorbs water and nutrients which the plant needs to live and grow. The water and nutrients are transported from the roots through the stem to the leaves. The evaporation of water from pores in the leaves pulls water through the plant. This is called transpiration.

A plant needs sunlight, carbon dioxide, minerals and water to make food by a process called photosynthesis. A green substance in plants called chlorophyll, found mostly in leaves, traps the energy from the sun needed to make food. The leaf can be thought of as a food factory. Leaves of plants vary in shape and size, but they are always the plant organ best suited to capture solar energy. Food made in the leaf of the plant is transported to the other parts such as stems and roots.

Orchard

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Crops are plant or plant products that are grown deliberately. Food crops, such as fruit and vegetables, are harvested for human consumption. Grains, such as corn, wheat, and rice, are the world’s most popular food crops. Examples are wheat, maize and rice, all vegetables and fruit, flowers and even special grasses. Food crops were the first crops to be harvested through agriculture. Agricultural development and the growth of civilizations led to the diversity of other types of crops. Climate, topography and soil types will significantly influence what can grow where. Crops are easily identified as they are usually laid out in neat patterns to maximise utilisation of the land, to facilitate irrigation (where required) and harvesting, especially where machinery is involved.

Crops can be sold ‘fresh’ as harvested or sent on for further processing e.g. wheat for flour, fruit juices. Local micro-climates to protect and enhance crops can be created using large expanses of shade netting and controlled irrigation.

Irrigation

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Irrigation is the application of controlled amounts of water to land for the purpose of agricultural production. Adequate irrigation will influence the entire growth process from seedbed preparation, germination, root growth, transport and utilisation of nutrients, plant growth, crop yield and quality. Irrigation systems provide water to crops during periods of low rainfall.

An irrigation system comprises a water source (river, reservoir, tank, underground aquifer) with or without a pump, and a distribution system comprising pipes, valves and nozzles. Optimum results require equal distribution. A farmer/producer can control how much water to supply and when to apply it, but the irrigation system determines the uniformity of distribution.

Deciding which irrigation systems are best for your operation requires knowledge of equipment, system design, plant species, growth stage, root structure, soil composition, and land formation. Irrigation systems should encourage plant growth while minimising salt imbalances, leaf burn, soil erosion, and water loss. Losses of water will occur due to evaporation, wind drift, run-off and water (with its nutrients) sinking below the root zone.

Proper irrigation management takes careful consideration and vigilant observation.

A sac spider, Cheiracanthium species, that can be found on different crops. Photograph by Peter Webb.

Spider

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Spiders are one of the most common predator groups in South African agricultural ecosystems. This means they are abundant predators occurring on various crops, including orchards. They are considered to be natural control agents against pests and mites occurring on crops.

How are spiders able to help control pests and mites?
- Spiders are present on crops throughout the year. Their lifespan, that vary from species to species, have instars or juveniles stages that actively feed as predators. Food consumption decreases only before and during ecdysis. Ecdysis is the process where the spiders moult and shed their exoskeletons.

- The fact that spiders are usually polyphagous helps them to act as a natural control agents for pests and mites. Polyphagus means that spiders feed on a variety of available prey. They do not feed on adult prey only, but on different stages of the insect or mite. Research has shown that spiders are often some of the first predators to arrive and colonise a newly planted crop, which is important as many pests attack in the early stages of the crop during the growing season.

- Different species of spiders are found in different microhabitats. Wandering spiders live on the ground and they feed mainly on ground-living insects and larvae hibernating in the soil. The plant-dwelling spiders are present on the stems, foliage, bark or flowers of plants. Many of them are active hunters and move around in search of prey. A number of web-building spiders spin their webs between the leaves and branches, under the bark and even over the leaf surfaces. They will prey on insects that come into contact with the silk threads of their webs.

- As predators, spiders have a two-fold effect. Not only do they feed directly on their prey, but their presence also causes indirect mortality. For example, the presence of foraging spiders can disturb insect larvae, which then drop from the plant and die, or are exposed to predation by ground dwelling predators. The webs spun over the leaves also seem to make them less suitable for oviposition and feeding by pests.