Theory question 103
Soil Fertility and Plant NutritionWrite short notes on the effects of the following farm practices on soil:
(a) bush burning
(b) fertilizer application
(c) grazing
(d) crop rotation.
Show the model answer
(a) Bush burning: destroys organic matter and soil organisms; exposes soil to erosion; loses nitrogen and sulphur; adds potash (ash) and may raise pH; kills weed seeds and some pests
(b) Fertilizer application: adds nutrients and raises fertility and yield; excess or wrong type can make soil acidic, harm soil organisms and pollute water
(c) Grazing: dung and urine add nutrients; overgrazing removes plant cover, compacts soil by trampling and causes erosion
(d) Crop rotation: maintains fertility (legumes add nitrogen); different rooting depths use nutrients from different layers; breaks pest and disease cycles; controls weeds and erosion
For each practice give both the good and the bad effects on the soil.