Make a careful observation of specimens A ( Sandy Soil), B (Clay), C ( Loam), and use your observations to answer questions (a) – (d)
(a) State three characteristics of each of specimens A. B and C
(b) Which of the specimens is the most suitable for crop production? Give two reasons for your answer.
(c) List four arable crops that can thrive Well on specimen C.
(d) State one way of improving specimen B.
Explanation
(a)Characteristics of specimens:
- Specimen A - Sand or Sandy soil: It contains single-grained, loose or large particles; coarse and gritty or rough, has large pore spaces, therefore well-aerated, rate of water percolation is high / well-drained - not pliable or plastic, and cannot form cast when moistened. The colour is grey or brownish, it has lower water retention capacity and cannot retain water easily.
- Specimen B - Clay / Clayey soil. It contains small fine powdery compact particles. It is smooth and velvety. It has tiny pore spaces hence not well aerated. The rate of water percolation is low. It has high water retention properties. It is always heavy to work when moistened or sticky and slippery. It is friable/plastic and easy to mould. The colour is grey or brownish. It is cohesive.
- Specimen C - Loam: dark coloured, contains organic matter/residues, has moderate-sized pore spaces. The rate of water percolation is moderate, not as coarse as sand nor as smooth as clay.- It is dark brown or black in colour, fairly friable and weaky plastic.
(b) Specimen best for crop production is C -Loam. Reasons: -
- has a moderate capacity for absorbing and holding water;
- contains organic matter which is a source of plant nutrients when decomposed,
- cannot be waterlogged well aerated for root respiration and development;
- does not easily lose its nutrients through leaching.
(c) Crops that thrive well on specimen C are:
- maize,
- rice,
- cowpea,
- cassava,
- yams,
- tomatoes,
- okro,
- millet,
- pepper etc.
(d) Ways of improving physical characteristics of specimen B clay by adding organic manure and liming.