Theory question 104
Soil Properties(a) List three edaphic factors that influence crop growth.
(b) Explain the following terms as used in soil and water conservation: (i) gravitational water; (ii) hygroscopic water.
(c) State two deficiency symptoms of each of the following nutrient elements in crops: (i) nitrogen; (ii) phosphorus; (iii) potassium.
(d) State three benefits derived from draining farmlands.
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(a) Any three: soil texture; soil structure; soil pH; soil water; soil air; soil temperature; nutrient content; soil organisms; topography.
(b)(i) Gravitational water: excess water that drains down through large pores under the pull of gravity after heavy rain or irrigation; not held by the soil and not available to plants for long.
(ii) Hygroscopic water: a very thin film of water held tightly around soil particles; plants cannot absorb it.
(c)(i) Nitrogen: yellowing of older leaves; stunted growth.
(ii) Phosphorus: purple/reddish colour of leaves; poor root growth; delayed maturity.
(iii) Potassium: scorching of leaf margins; weak stems/lodging; poor quality fruits.
(d) Any three: improves aeration; allows deeper root growth; raises soil temperature; reduces toxic substances; makes early tillage possible; increases activity of useful organisms.
Two symptoms for each nutrient.