i)

Effects of soil erosion on the growth of crop plants

1. Loss of soil nutrients or nutrient imbalance or poor crop growth or yield
2. Destruction/death of crops
3. Increased cost of production or high doses of fertilizer needed to replenish soil
4. It is difficult to move farm machinery due to gullies
5. It causes siltation of dams or irrigation channels
6. Degradation of soil structure
7. Loss of rooting depth
8. Poor/stunted growth
9. Shows deficiency disease
10. Lodging of crop plants

ii)

Method of controlling soil erosion

1. Terracing
2. Strip cropping
3. Contour ploughing
4. Wind breaks/afforestation/planting
5. Mulching
6. Cover cropping
7. Crop rotation
8. Application of ogranic manure
9. Minimum/zero tillage
10. Afforestation

(i)

Fertile soil is a soil that has essential nutrients to support the growth/development of crops.

OR

Fertile soil is a soil that has an abundance of plant nutrients/minerals orgamic matter to support plant growth.

OR

Fertile soil is a soil which contains all the major nutrients for basic plant nutrition as well as others to support plant growth.

OR

Fertile soil is a soil which is able to provide all essential plant nutrients in available forms and in a suitable balance to support plant growth.

(ii)

Factors that cause loss of soil fertility

1. Soil erosion
2. Leaching
3. Bush burning
4. Continuous cropping or monoculture
5. Deforestation
6. Overgrazing
7. Illegal mining
8. Soil acidification/salinization/alkanization
9. Inefficient soil management practices
10. Soil pollution/indiscriminate use of agro-chemicals

(i)

Examples of major plant nutrients

1. Nitrogen (N)
2. Phosphorus (P)
3. Calcium (Ca)
4. Magnesium (Mg)
5. Sulphur (S)
6. Potassium (K)

(ii)

Examples of minor plant nutrients

1. Copper (Cu)
2. Iron (Fe)
3. Zinc (Zn)
4. Manganese (Mn)
5. Boron (B)
6. Chlorine (Cl)
7. Cobalt (Co)
8. Molybdenum (Mo)

i)

Difference between organic fertilizer and inorganic fertilizer

Organic fertilizer is obtained from plant and animals whilst inorganic fertilizers are obtained from artificial/synthetic/non-living/chemical materials.

ii)

Effects of inorganic fertilizer on the environment

1. It pollutes water bodies/causes air or land pollution
2. It increases soil acidity
3. It kills plants and other organisms in the soil

i)

Fertilizer is any substance which is applied to the soil or plant to supply nutrients for plant growth.

ii)

Examples of an inorganic fertilizer

1. Urea
2. Muriate of potash
3. Single super phosphate (SSP)/sulphate of ammonia
4. NPK

i)

Soil erosion is the washing away/removal of the top soil by water or wind

ii)

Methods of controlling soil erosion

1. Terracing
2. Strip cropping
3. Contour ploughing
4. Wind breaks/afforestation/tree planting
5. Mulching
6. Cover cropping
7. Practising crop rotation
8. Bush fallowing/land rotation

(i)

Symptoms of nitrogen deficiency in a tomato plant

1. Yellowing of leaves/chlorosis
2. Stunted growth
3. Weak and slender stems

(ii)

Side dressing is the application of fertilizer at one or both sides of crops on the surface of the soil while the crops are growing.

i)

Soil erosion is the removal/washing away of soil particles/topsoil by running water or rain or wind.

ii)

Types of soil erosion

1. Gully
2. Rill
3. Sheet
4. Splash

i)

Human activities that can cause an increase in soil erosion

1. Road construction
2. Bush fires
3. Deforestation
4. Farming/over-cropping
5. Sand wining/soil removal for building and road construction
6. Over-grazing by farm animals

ii)

Ways of preventing soil erosion in agriculture

1. Ploughing across slopes/Contour ploughing
2. Growing of cover crops
3. Practicing crop rotation
4. Afforestation and reafforestation
5. Bush fallowing/land rotation
6. Erecting windbreaks
7. Terracing
8. Strip cropping
9. Mulching

(i)

A fertile soil is the soil rich in nutrients (mineral salts) which are essential for the healthy growth of a specific plant.

(ii)

Most important nutrients in mineral salts which plants use to form food

1. Nitrogen
2. Phosphorus
3. Potassium
4. Calcium

(i)

Soil resources

Soil resources are materials/components in the soil that support plant growth

(ii)

Agricultural activities that make the soil lose its nutrients

1. Continuous cropping/over cropping
2. Excessive drainage/run off
3. Burning of organic matter/bush burning
4. Irrigation leading to leaching
5. Crop removal
6. Over grazing
7. Poor tillage practices
8. Excessive use of chemical fertilizers

(i)

Activities of man that can cause soil erosion

1. Road construction
2. Bush fires
3. Deforestation
4. Farming/over-cropping
5. Sand wining/soil removal for building and road construction
6. Over-grazing by farm animals

(ii)

Ways by which soil can be conserved

1. Cover cropping
2. Crop rotation
3. Green manuring
4. Fertilizer application
5. Liming
6. Composting
7. Mixed farming
8. Mixed cropping
9. Alley cropping
10. Mulching
11. Bush fallowing
12. Application of farm yard manure/kraal manure/poultry manure
13. Use of leguminous crops to fix nitrogen
14. Tillage to improve aeration
15. Irrigation
16. Afforestation and reafforestation
17. Land rotation
18. Contour ploughing
19. Erecting windbreaks

i)

Functions of nitrogen in plants

1. For plant growth/vegetative growth
2. Increases yield of straw
3. A constituent of organic compound of plants
4. For plant development
5. Increases seed and fruit production
6. To make proteins
7. To make chlorophyll

ii)

Functions of potassium in plants

1. Plays an important role in plant metabolism
2. Plays an important role in translocation of starch to growing parts
3. Plays an important role in carbohydrate formation
4. Neutralization of organic acids
5. Strengthens straw and stalk of plants
6. Aids absorption of nutrients
7. Helps to reduce diseases in plants
8. Helps to produce quality fruit and promotes seed development
9. Activates enzymes for photosynthesis and respiration
10. Helps build proteins
11. Aids absorption of nutrients

i)

Depletion of soil resources by burning

1. Causes escape of volatile nutrients
2. Destroys organic matter/vegetative cover
3. Destroys microbes/soil animals/soil organisms
4. Exposes soil to erosion
5. Enhances leaching of soil nutrients

ii)

Depletion of soil resources by Leaching

1. Dissolved nutrients are lost/out of reach to plants roots
2. Causes soil acidity
3. Weakens soil structure

i)

Macro nutrients

1. Nitrogen (N)
2. Phosphorus (P)
3. Potassium (K)
4. Calcium (Ca)
5. Magnesium (Mg)
6. Sulphur

ii)

Micro nutrients

1. Copper (Cu)
2. Zinc (Zn)
3. Molybdenum (Mo)
4. Iron (Fe)
5. Boron (B)
6. Cobalt (Co)
7. Chlorine (Cl)
8. Manganese (Mn)
9. Sodium (Na)

i)

Methods of restoring soil resources

1. Fertilizer application/organic composting
2. Land rotation
3. Afforestation/re-afforestation
4. Mulching
5. Cover cropping / green manuring
6. Crop rotation with legumes

ii)

Land rotation

1. This is a system of farming in which a farmer cultivates a piece of land for sometime and leaves it to clear a new land when the old land becomes less fertile

2. It helps check the spread of diseases
3. Land regains lost nutrients after the fallow period
4. Checks spread of pests

Cover crop or green manuring

1. Crops/plants are grown to cover the soil to maintain soil fertility/moisture or to enrich the soil
2. They increase the soil organic matter

Crop rotation

1. Involves growing different types of crops in one location across a sequence of growing seasons
2. It reduces soil erosion
3. It increases soil fertility

Mulching

1. Its the process of using garden leftovers such as leaves, green chipping and shredded trees to cover any bare soil in the garden
2. It improves the soil texture and slow moisture evaporation
3. It also returns organic material and nutrients to the soil