Grade 10 Agriculture Crop Production – Properties of soil Notes

1. a) Investigate components of soil that influence crop production
2. b) Examine properties of a soil for crop production
3. c) Describe properties of soil that influence crop production
4. d) Investigate selected properties of soil that influence crop production
5. e) Relate importance of soil profile to crop production
6. f) Acknowledge importance of soil properties in crop production

1. What is soil and its main components?

Soil is the natural medium that supports plant growth. It is made of:

• Mineral particles — sand, silt, clay (determine texture).
• Organic matter — decomposed plants and animals (improves fertility, water holding).
• Water — held in pores; available water controls growth and irrigation needs.
• Air — oxygen in pore spaces for root and soil organism respiration.
• Living organisms — earthworms, microbes, termites (help nutrient cycling).

2. Important properties of soil (simple descriptions)

1. Texture (proportion of sand, silt, clay)
   - Sandy soils drain fast, warm quickly, low water holding; best for root crops if well fertilized.
   - Clay holds water and nutrients but may be poorly drained and heavy to work.
   - Loam (mix) is best for most crops (maize, vegetables).
2. Structure (how particles form aggregates)
   - Granular or crumb structure is good for roots and aeration; blocky or platy may restrict roots.
3. Soil depth/rooting depth
   - Deeper soils allow deeper roots and store more water (important in dry spells).
4. pH (acidity/alkalinity)
   - Affects nutrient availability. Most crops prefer pH 5.5–7.0.
   - Tea thrives at acidic pH (~4.5–5.5); some vegetables prefer near-neutral soils.
5. Nutrient status (N, P, K, Ca, Mg, S, micronutrients)
   - Low N causes pale leaves and poor growth; P affects roots and flowering; K affects yield and disease resistance.
6. Organic matter
   - Improves soil structure, water holding, nutrient supply and supports soil life.
7. Porosity & bulk density
   - Porosity controls water and air movement. High bulk density (compaction) reduces root growth.
8. Water holding capacity & drainage
   - Soils must balance holding enough water for crops but allow excess to drain to avoid waterlogging.
9. Colour
   - Dark soils usually have higher organic matter. Red/yellow may indicate good drainage and iron oxides.
10. Salinity
    - High salt levels reduce crop growth (important in some irrigated areas/coastal soils).

3. Soil profile — why it matters

4. Investigations & simple practicals (class/field)

These practicals help meet outcomes a, b, d, e (investigate & examine).

A. Texture: Ribbon test (hand test)

Materials: soil sample, water, bowl, hands.

1. Take moist soil, roll between palms into a ribbon.
2. If it forms a long ribbon = high clay. Short crumbly = sandy. Smooth, slightly sticky = loam.
3. Record observation and explain which crops (e.g., Irish potato prefers well‑drained loam) fit the soil.

B. Jar sedimentation test (estimate sand:silt:clay)

Materials: clear jar, water, soil, marker.

1. Fill jar with soil + water, shake, let settle: sand first (bottom), silt next, clay last (top) over 24 hrs.
2. Measure layer heights to estimate percentages and classify texture (relate to crop needs).

C. pH test (simple)

Materials: pH paper or meter, soil sample, distilled water.

1. Mix soil with water, dip pH paper or meter. Record pH. Suggest lime if too acidic for maize or sulfur if too alkaline for some crops.

D. Infiltration / drainage test

Materials: measuring stick, stopwatch, small container to place on soil, water.

1. Dig small hole, pour known volume of water, measure time to drain. Slow drainage indicates poor drainage or compacted soil — affects crop choice and need for drainage.

E. Soil profile pit (school farm)

Dig a small safe pit (about 1m x 1m x 0.7m) with supervision. Observe horizons, colour, root depth, stones. Relate to choice of crop and tillage.

F. Nutrient deficiency observation

Compare leaf symptoms on plants (yellowing, stunting). Collect samples for simple N/P/K tests at local extension or agricultural lab.

5. Kenyan context — soil types and crop examples

• Highlands (central, parts of Rift Valley): red–brown loams with good fertility — ideal for maize, beans, tea (in specific areas).
• Western Kenya: heavy black cotton soils (Vertisols) — can be fertile but may be waterlogged; suitable for cotton, some cereals with drainage management.
• Coastal sands: light, sandy, low fertility — good for coconut and some vegetables with irrigation and fertilizer.
• Tea and coffee areas: need well‑drained, acidic soils rich in organic matter (e.g., Limuru, parts of Kericho).

Tip: Use local extension services or Kenya Agricultural & Livestock Research Organization (KALRO) for soil testing and fertilizer recommendations.

6. Suggested learning experiences (for teacher & learners)

• Field trip to a nearby farm to see soil management (terracing, cover crops).
• Group practicals testing texture, pH and drainage on school farm plots; each group presents findings and crop suggestions.
• Record-keeping: keep a simple soil test book with photos, descriptions and recommendations.
• Invite an agricultural extension officer to demonstrate soil testing kits and talk about fertilizers and lime.
• Small project: build compost and measure soil improvement (colour, structure) over a term.

7. Assessment tasks (short)

1. Practical report: Do a ribbon test and jar test; state soil texture and suitable crops for your school farm plot (addresses a, b, d).
2. Short answer: Explain three ways soil pH affects crop growth and give one Kenyan crop example for acidic soil (addresses c).
3. Group presentation: Show a soil profile photo, identify horizons and explain which layer is most important for crop growth and why (addresses e).
4. Reflection: Write why soil properties are important in planning crop production (addresses f).

8. Safety & practical tips

• Wear gloves and boots when digging soil pits.
• Always work with a teacher or adult when using tools or chemicals (pH solutions).
• Label samples and keep testing equipment clean to avoid contamination.

Soil properties (texture, structure, pH, depth, organic matter, porosity and nutrients) control water, air and nutrient supply to crops. By examining and testing soils on your school farm and nearby fields you can choose the right crop, improve soils (compost, lime, proper drainage) and increase yields sustainably.

• a) Investigate components — practicals A, B, F (texture, jar, nutrient observation).
• b) Examine properties — practicals and profile pit (structure, depth, drainage).
• c) Describe properties — core notes and examples explain how each property influences crops.
• d) Investigate selected properties — pH test, infiltration test, jar test, profile observations.
• e) Relate profile to production — soil profile SVG explanation + pit activity.
• f) Acknowledge importance — summary, suggested experiences and assessment reflection.