FACTORS WHICH INFLUENCE AGRICULTURE
1. Two roles of humus in the soil that is beneficial to crops
- Provide nutrients
- Increase water holding capacity
- Increase soil temperature
- Neutral soil PH
2. Five activities that may be undertaken in organic farming
- Mulching
- Apply manure
- Use medicinal plants to control parasites and diseases
- Crop rotation
- Rear livestock on natural organically grown pasture
- Physical/ cultural/ biological/ pests, weeds and disease control
3. Four effects of temperature on crop growth
- Low temp-slow growth rate
- increase incidence of negative infection e.g. CBD
- improve quality of some crop
- High temp-cause wilting
- increase growth rate
- improve quality of some crops
- increase pest and disease incidences (1/2x4=2mks)
4. Four ways by which wind affects the growth of crops.
- Causes physical damage to crops.
- Cause rapid spread of diseases/ pests/ weeds.
- Can cause water stress as a result of evaporation.
- Causes stress of crops due to chilling caused cold winds.
- Encourage transpiration hence water and mineral uptake.
5. Two factors related to light that affect crop production and distribution in Kenya:-
- Light intensity
- Light duration
- Light wavelength
6. The environmental conditions that may lead to low crop yields
- Poor soil fertility /infertile soil
- Damage by hailstorms
- Less rainfall/unreliable/drought
- Poor soil type resulting into leaching or water logging
- Inappropriate soil PH
- Inappropriate temperature (too low or high)
- Excessive wind leading to increase in water loss from the soil
- Extreme relative humidity
- Extreme of light intensity
- Topography / some attitudes e.g. very high may limit crop growth ( 1mk x any 7pts = 7mks)
8. One physical characteristic used in classifying soil is:
- Colour,
- Texture,
- Structure
9. Four advantages of organic farming
- Environmental friendly
- Products do not have organic farming
- Products do not have organic chemical residue
- Improve soil structure
- Replenishes nutrients in the soil as it uses organic manure
- Enhances soil water retention
- Provides food for soil microbes
- Enhances soil water infiltration ( 4x ½ = 2mks)
11. Briefly explain how sub-soil as a horizon in a soil profile can affect soil productivity
- It may have hard pan which interfere with water infiltration
12. (a) What are the three aspects of light that are important to a farmer?
- Light duration
- Light intensity
- Light wave length
15. a) State merits of horizon A
- source of plant nutrients
- support/anchor the crops
- store of water for the crops
- sources of soil micro organism
b) State distinct features of horizon B
- deficient of humus(nutrients)
- contain leached nutrients
- contains more compact soil particles
- presence of hard pans in some soils
c) What does the term transition zone refer to in soil profile
- Transitional zone-this is a zone bordering two adjacent layer of soil profile
d) Name horizon C and state its importance
Weathered rock
Importance
- Give rise to sub soil
- Source of minerals
- Determine mineral content of soil and type of soil
16 Outline two ways temperature affects crop production
- Low temperatures encourages crop diseases such as leaf rust
- Low temperatures may increase or lower the quality of farm produce
- High temperatures hastens maturity/ improves the quality/ lower the quality
- Increases the rate of evapo transpiration which may result loss plant moisture/ leading to wilting of crops
17. List four ways by which biological agents can enhance the process of soil formation
- Movement of animals in large numbers
- Decomposition of plant and animal remains by soil micro- organisms
- Physical breaking of rocks by roots of higher plants
- Man’s activities e.g. cultivation, mining and road construction
- Mixing up of soil by animals e.g. earth worms and
18. List four environmental factors that affect crop production in Kenya
- Temperature/ Altitude
- Soil type;
- Prevailing winds;
- Rainfall; (4x ½ =2mks)
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19. Explain the role played by topography in soil formation
- It influences the movement of the weathered materials hence affecting the depth of soil development;
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