Local climatic conditions

Way it has been managed

Type of soil;

Size of the mineral particles

Legumes: have nitrogen-fixing bacteria in their root nodules.

Leafy crops: vegetables that are required for their leaves (require a lot of nitrogen left by legumes).

Root crops: have deep root systems.

SubtopicFallow: the land is ploughed but left barren for a period to restore soil fertility and to avoid surplus production.

Advantages of crop rotation:

Fertilisers: contain minerals such as nitrogen, potassium and phosphorus. Add on to the nutrients available in the soil.

Irrigation: supplying water to the crops.

Pest: an animal that attacks or feeds upon a crop plant.

Pesticide: used to control pests.

Weed control: weed-killing chemicals are known as herbicides.

A crop disease is caused by fungi, bacteria or viruses (pathogens).

Insect control: insect-controlling chemicals are called insecticides.

Addition of extra mineral nutrients is waste of money and resources if the soil has reached its maximum level; o Heavy rain can dissolve the nutrients and cause leaching; o Excess water containing dissolved fertilisers drain into nearby lakes and rivers, leading to eutrophication; o Nitrates from fertilisers if consumed can cause diseases such as blue-baby syndrome; o Large quantities can affect the pH of the soil and in turn, the availability of minerals; o Too much of trace elements can be toxic to the plant. o Too much fertiliser dehydrates the plant (scorching); o Imbalance of nutrient makes the plant produce lots of foliage, but no flower.

Solution: strict limits on where, when and how the fertilisers must be applied; can replace with organic fertilisers.

Waste from overproduction: the unsold proportion of the crop.

Waste of storage space: may take longer to sell a crop; some crops need special conditions.

Waste of transportation: to sell a crop, a farmer may need to travel longer distances.

Provides additional air gaps in the soil ؞ improves soil structure;

Increases decomposers in the soil as they feed on the matter;

Adds nutrients to the soil after decomposition.

Acts like a sponge, holding the extra water, preventing dehydration of the soil;

Reduces soil erosion as the organic matter acts like a base to smaller particles.

Meeting the needs of the population for agricultural products;

Making efficient use of non-renewable resources;

Supporting the natural ecosystem by following natural processes with farming techniques;

Sustaining the economic independence of farmers

Are slow acting ؞ reduces the risk of eutrophication;

Are a waste product ؞ using them saves on disposal costs;

Are already present on many farms ؞ minimal transport costs;

Do not require energy for their manufacture;

Also improve soil structure.

Prevention of overgrazing;

Ensure sufficient grazing;

Maintaining appropriate soil fertility by animal waste;

Maintaining good drainage prevents compaction of the soil.