By Elimu Assistant Team 
Self-Assessment: Factors Influencing Agriculture Topical Revision for KCSE
🌿 KCSE Agriculture Revision
Factors Influencing Agriculture
Learning Progress0 / 18 revealed
Climatic & Environmental Factors
1
List four environmental factors that affect crop distribution in Kenya. [cite: 4]
Model Answer
- Temperature/altitude [cite: 85]
- Prevailing winds [cite: 86]
- Soil types [cite: 87]
- Rainfall [cite: 88]
2
State ways by which wind affects the growth of crops. [cite: 6]
Model Answer
- Causes physical damage/breakages to crops [cite: 89]
- Increases rate of transpiration/causes water stress [cite: 90]
- Spreads crop pests, diseases, and weeds [cite: 91]
- Causes chilling stress due to cold air [cite: 92]
- Causes soil erosion leading to loss of fertility [cite: 93]
- Encourages transpiration hence water/mineral uptake [cite: 94]
3
State two roles of micro-organisms in the soil and properties influenced by texture. [cite: 11, 13]
Model AnswerMicro-organism Roles:
- Decompose organic matter [cite: 116]
- Help to aerate the soil [cite: 117]
- Fix atmospheric Nitrogen to nitrates [cite: 118]
- Release plant nutrients upon death and decay [cite: 119]
4
List down the four aspects of rainfall that affect agriculture. [cite: 15]
Model Answer
- Rainfall intensity [cite: 95]
- Rainfall reliability [cite: 96]
- Rainfall distribution [cite: 97]
- Rainfall amount [cite: 98]
5
Describe environmental conditions that lead to low crop yields. [cite: 17]
Model Answer
- Poor soil fertility (lack of manure/fertilizer) [cite: 103]
- Unreliable or excessive rainfall [cite: 105]
- Poor soil type leading to waterlogging/leaching [cite: 106]
- Inappropriate pH [cite: 107]
- Pest attacks and poor weed control [cite: 108, 109]
- Temperature extremes [cite: 110]
- Excess wind/hailstorms [cite: 111, 115]
Soil & Edaphic Factors
6
Outline three effects of soil organisms which benefit crop growth. [cite: 19]
Model Answer
- Organic matter decomposition [cite: 116]
- Soil aeration improvement [cite: 117]
- Nitrogen fixation [cite: 118]
7
State two causes of hard pan in a crop yield. [cite: 21]
Model Answer
- Ploughing at the same depth season after season [cite: 120]
- Use of heavy machinery on wet soil [cite: 121]
8
Processes of rock weathering and definitions of texture vs structure. [cite: 24, 26]
Model AnswerWeathering Processes: Physical, Biological, and Chemical [cite: 124, 126, 127].
Difference: Texture is the relative proportion of different sized particles[cite: 129]. Structure is the arrangement of individual soil particles[cite: 130].
Difference: Texture is the relative proportion of different sized particles[cite: 129]. Structure is the arrangement of individual soil particles[cite: 130].
9
Capillarity Experiment: Study the diagram of soil types G, H, and J. [cite: 32-46]
Model Answer
- Study Subject: Capillarity in three soil samples [cite: 142].
- Soil Types: G-Sandy, H-Loam, J-Clay [cite: 144-146].
- Texture: G is rough/coarse; J is fine textured [cite: 148, 149].
- Improvement for G: Add organic manure or lime[cite: 150].
10
Why is soil important and what are the benefits of optimum temperature? [cite: 57, 59]
Model AnswerImportance: Anchorage, nutrients, water, and organic matter for microorganisms [cite: 155-158].
Temp Benefits: Increases biochemical reaction rates, activates nitrogen-fixing bacteria, and enhances germination [cite: 161-165].
Temp Benefits: Increases biochemical reaction rates, activates nitrogen-fixing bacteria, and enhances germination [cite: 161-165].
Productivity & Management
11
Give three reasons why soil is important to crops. [cite: 63]
Model Answer
- Anchorage to roots [cite: 173]
- Provides nutrients [cite: 174]
- Provides water and oxygen [cite: 175, 176]
12
Reasons for well-drained soil and factors of soil productivity. [cite: 66, 71]
Model AnswerDrainage: Necessary for respiration, microbial activity, and removing toxic salts [cite: 180, 181, 184].
Productivity Factors: Soil depth, aeration, water holding capacity, and pH [cite: 193-196].
Productivity Factors: Soil depth, aeration, water holding capacity, and pH [cite: 193-196].
13
State three advantages of adding organic matter to sandy soil. [cite: 73]
Model Answer
- Improves soil structure [cite: 197]
- Reduces leaching [cite: 198]
- Improves water holding capacity [cite: 199]
- Increases cation exchange capacity [cite: 200]
14
Role of soil aeration and aspects of light. [cite: 76, 30]
Model AnswerAeration: Root respiration and microbial activity [cite: 180, 181].
Light Aspects: Intensity, wavelength, and duration [cite: 137-139].
Light Aspects: Intensity, wavelength, and duration [cite: 137-139].
Quick Review
15
State three benefits of good soil structure. [cite: 28]
Model Answer
- Proper infiltration/drainage [cite: 132]
- Good aeration [cite: 133]
- Resistant to erosion [cite: 134]
16
List soil factors influencing productivity. [cite: 61]
Model Answer
- Nutrient supply [cite: 167]
- Drainage and water retention [cite: 169, 171]
- Soil organisms and freedom from pests [cite: 170, 172]
17
State two benefits of optimum soil temperature. [cite: 69]
Model Answer
- Enhances seed germination [cite: 186]
- Enhances plant growth and microbial activities [cite: 188, 189]
18
How does organic matter affect soil pH and temperature? [cite: 81]
Model Answer
- Moderates soil temperature [cite: 202]
- Buffers the soil pH [cite: 202]
