ZIMSEC O Level Geography Notes:Agriculture:Human Farm Inputs: Seeds and Fertilizer
- These determine the germination rate, growth status and productivity level of crops.
- Traditional farmers use seeds from the previous year’s harvest.
- These seed mostly would have been damaged by fungi, insects and rodents such that their germination rate is very poor.
- A modern farmer at the other hand, uses hybrid seeds treated with chemicals.
- Such seeds have nearly 100% germination rate, the plants grow healthy and yields are very high.
- These come in different forms.
- Traditional varieties include cowdung, anthill soil, night soil, humus, boma manure and potash (ash).
- Chemical fertilisers are manufactured from factories through chemical processes.
- These include all the nitrates, sulphates, ammonias and urea.
Problems currently being faced in the acquisition and use of both groups of fertilisers in Zimbabwe
- For traditional sources, cattle are too few now from dying from droughts and diseases resulting in very small amounts of cow dung being produced.
- Antihills have virtually disappeared through exploitation and overuse especially in communal areas.
- Trees are the major source of humus and ash. These too have reduced due to deforestation and desertification.
- Chemical fertilisers are very expensive for both communal and commercial farmers.
- Their continued use has negative effects on ecosystems.
- For example they pollute water, leading to eutrophication.
- Eutrophication is excessive richness of nutrients in a lake or other body of water, frequently due to run-off from the land, which causes a dense growth of plant life.
- Following this, overcrowding occurs and plants compete for sunlight, space and oxygen.
- Continued use of chemical fertlisers does not guarantee a proportional product from the soil as the law of diminishing returns starts operating.
- Shortage of real foreign currency to import necessary chemicals used in the manufacture of fertilizer and components used by the industry
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