Theory question 104
Irrigation and Drainage(a) State three methods of irrigating a small nursery.
(b) Enumerate three factors to be considered in the choice of each of (i) surface irrigation method; (ii) subsurface irrigation method
(c) State two advantages of subsurface irrigation
(d) Enumerate five ways by which the build-up of diseases could be reduced on an irrigated farm.
Show the model answer
(a) Any three: watering can; hose pipe; small sprinklers/overhead mist; drip; bucket and cup; furrow/basin
(b)(i) Surface (any three): level or gently sloping land; soil that is not too sandy (moderate infiltration); plentiful water supply; crop type; cost of land levelling
(ii) Subsurface (any three): soil with good capillarity and an impermeable layer below; high-quality water (low salts); capital for pipes; type of crop/rooting depth; water table level
(c) Any two: little water lost to evaporation; soil surface stays dry, reducing weeds and diseases; does not interfere with field operations; no erosion
(d) Any five: good drainage to prevent waterlogging; avoid over-irrigation; crop rotation; resistant varieties; clean water free of pathogens; sanitation (remove infected plants); control weeds that host pests; spray fungicides/pesticides; correct spacing for air movement; control snails and mosquitoes (bilharzia, malaria)
Answer every part separately.