Why we need plants to grow well
Humans, like other animals, cannot make their own food. They have to eat plants or animals for the nourishment they need to stay alive. The first people were called hunter-gatherers. They hunted animals such as large hairy elephants called mammoths, speared fish in rivers, gathered shellfish from the seashore and ate seeds, fruits and roots of many plants. In time most hunter-gatherers turned to farming their food. Let us imagine how farms became set up to give us the food we need today.

When you are a hunter-gatherer you have to search your surroundings for food. You may find that the grains of some grasses are quite good to eat but you have to travel great distances to collect enough for a meal for your family. In the past someone had the idea of making life a little easier by growing large amounts of the grass in the same place. When the grasses produced their grain all you would have to do is walk through the field and collect it. This is how the first farms came to be set up about twelve thousand years ago. The grasses that were grown were wild wheat and barley. They belong to the food plants called cereals.

In time other crops were grown in fields. These included carrots, grown for the food in their roots, and cabbage, grown for the food in their leaves. Plants which are grown for the food stored in their root, stem or leaves are called vegetables.

A major problem with growing the same plant in the same soil every year is that you give the plant's pests a chance to thrive. In the first year a few of the pests may invade the field and kill a few plants. During the winter some of the pests survive in the soil ready to attack again when new crops are sown in the spring. In the second year the attack by the pests is much worse than the year before and less food is produced for people to eat. In time the whole crop could be destroyed by the pests. Luckily someone had an idea about how to stop the pests ruining the crops.

They found that if a crop is grown in a field in one year a different crop should be grown the year after. This meant that the pests that waited in the soil to attack again found that a different crop was growing in the field the second year. As the pests could not feed on this new crop, they died. This did not mean that the first crop could not be grown. It just had to be grown somewhere else and that place was the field where the second crop had grown the year before. This might seem complicated but really all the farmer did was swap the crops around to fool, and kill, the pests. In time a plan was worked out to swap four crops around four fields. Every year a field received a different crop. This practice is called crop rotation and is still used today.

When crops are grown in the soil every year, they take nourishment out of it. In time the soil has so little nourishment that the crops grow poorly and there is little food to eat. When farmers rotate their crops they have one crop which is simply grass. This crop is not for humans but for farm animals. They graze the grass and and manure to the soil. The manure contains nourishment that the soil needs. In the following year, when a cereal or vegetable crop is grown in the grass field, the soil has plenty of nourishment to make the food crop grow well.

Today our food comes from farms all over the world. Whatever the farmers grow they take care to make their crops as healthy as possible so they can provide us with good wholesome food.

Do the same plants grow on different farms around the world?
No. The crops that are grown depend on the climate. If the climate is cool and wet, cereals like wheat or barley may be grown. If the climate is warm and wet, rice may be grown.

How are cereals different from other food plants?
They belong to the group of plants called grasses. The part that we eat is the cereal grain. This is a fruit filled with just one seed. Sometimes people call the grain a seed. The wheat grain is ground up to make flour. Barley grains are used in stews; oat grains are used to make porridge. We eat the whole grain when we eat rice or sweet corn. Other food plants are either vegetables or fruits.

What is the difference between a vegetable and a fruit?
A vegetable is a plant we eat that has a food store in its root, stem or leaf. Some vegetables such as broccoli and cauliflower have a food store in their flowers. A fruit is made from a flower. After a flower has received pollen from a bee or other insect it makes a fruit which has one or more seeds in it. Apples and oranges are examples of fruits. Some people mistakenly call some fruits vegetables. For example, the tomato is sometimes called a salad vegetable when really it is a fruit of the tomato plant. You have only to bite open a tomato to see its seeds. Pumpkins are also sometimes called vegetables but when you open them you may find hundred of seeds.

Are fruits grown on a farm?
Fruits are grown in an orchard. This is an area of land on which fruit trees grow. In warm climates huge numbers of fruit trees may be grown together. These places are known as plantations.

Do all farms grow crops and have animals?
No. Some farms just grow crops. They are called arable farms. Some farms just have animals. When cattle and sheep are kept on a farm the pastures or fields of grass on which they feed have to be kept healthy just like the fields of crops on an arable farm. The main problem in making a healthy pasture is keeping down the number of weed plants. Some of them are poisonous to the animals.

Is manure the same as fertiliser?
No. Manure is the solid waste produced by animals. It contains minerals and fibre that the animal has not digested. The minerals provide nourishment for the soil and the fibre is slowly broken down to make the humus in the soil. The humus helps the grains of soil stick together to form lumps called crumbs. The crumbs have spaces between them, which let water drain easily through the soil. The spaces also let air enter the soil and reach the roots. This helps the roots grow well. Fertiliser just contains minerals. It is made in a factory. When it is spread on the soil the minerals add nourishment to the soil but they do not add any humus. A farmer may use both manure and fertiliser on a farm at different times of year.

Why may a farmer use both manure and fertiliser?
The minerals in the manure are only released into the soil slowly. The minerals in a fertiliser are ready immediately for the plants to use. When the crop has reached a certain stage of growth, the farmer may decide to add some fertiliser to the soil to make the crop grow faster. Manure is important to build up the soil nourishment over a long time and to let air and water move through the soil.