(a) Define soil erosion. [2 marks] (b) List four factors that influence nutrient availability in

Explanation

(a)Definition of soil erosion: This is the wearing away of soil by means of natural agents such as water, ice/ glacier, and wind.

(b) Factors that influence nutrient availability in the soil:

Soil pH, Concentration of other nutrients, Leaching, Crop removal/overgrazing, Oxidation and Reduction, Burning, Erosion, Soil moisture content, Level of organic matter/microorganisms in the soil

(c) Explanation of roles of factors of soil formation (i)Climate

- Abrassive action of rock particles blown by wind

- Rain may be severe enough to cause erosion

- Rain water causes chemical change of rock minerals' aids chemical weathering

- Temperature causes the expansion and contraction of rocks alternately leading to minerals with low expansitivity breaking away to form soil.

(ii) Living organisms

- Soil organisms like termites, earthworms eat deep into the soil and mix the mineral and organic matter together resulting in the formation of soil

- Activities of man during farming operation help to break rocks into tiny particles to form soil

- Roots of plants grow into openings in the rocks, physically forcing the rocks apart into smaller particles,

- Human activities can also cause erosion which result both in soil destruction and formation.

- Living organisms produce carbon dioxide which forms carbonic acid with water and enhances rock weathering,

(iii) Topography

-The shape of the land influences the movement and amount of water in the soil

- Hilly and slopy surfaces support erosion and encourage soil formation

- A flat and exposes the whole surface to equal environmental factors and therefor delays soil formation

- The topography of the land affects the distribution 0,i, plants and animals which influence the process of 01 formation

- More soil formation in the valleys than at the top of the hills

(d) Problems associated with overhead irrigation -

Wind distorts sprinkler patterns and causes uneven distribution of water

- The spray force can damage ripening soft fruits.

- A stable water supply is required for economic use of the equipment

- The water must be clean and free of sand, debris and large amounts of dissolved salts

- The initial investment is usually high

- Power requirements for pumping water is high

- Requires technical know-how

- Can spread diseases

- Lateral pipes hinder movement of farm machines

- High cost of maintenance/repairs/spare parts not readily available.