Factors affecting crop production
| Factor | Examples |
|---|---|
| Climatic | Rainfall, temperature, light, wind, humidity |
| Edaphic (soil) | Fertility, texture, pH, drainage, depth |
| Biotic | Pests, diseases, weeds, pollinators |
| Human and economic | Skills, capital, markets, roads, government policy |
Seeds and planting materials
Good seed is pure, viable (alive), free from disease and true to type. Seed can be sexual (true seeds) or vegetative (stem cuttings of cassava, sweet potato vines, suckers of banana, tubers of potato, setts of sugarcane). The best seed comes from certified suppliers. Germination percentage tells how many seeds out of 100 grow. To find the seed rate needed, correct for germination.
A farmer needs 40 000 plants per hectare. The seed has 80% germination. How many seeds are needed?
- Divide by 0.8.
Answer: 50 000 seeds per hectare.
Methods of planting and sowing
| Method | Description | Crops |
|---|---|---|
| Drilling | Seeds placed in rows by hand or planter | Maize, beans |
| Broadcasting | Scattering seeds over the surface | Pasture grasses, rice in some places |
| Transplanting | Raising seedlings in a nursery and moving them | Tomato, cabbage, tobacco, rice |
| Vegetative planting | Planting cuttings, tubers, suckers | Cassava, banana, sugarcane |
Seed should be planted at the start of the rains, at the right depth (about 3 to 4 times the seed size), and with the right spacing. Then comes gapping (replacing seeds that failed), thinning, weeding, fertiliser application, pest and disease control and mulching.
Choose the plants wanted per hectare and the germination percentage.
Key terms
- Viability
- The ability of a seed to germinate.
- Gapping
- Replacing missing plants.
- Thinning
- Removing extra seedlings.
- Transplanting
- Moving seedlings from a nursery to the field.
Summary
- Climate, soil, biotic and economic factors affect production.
- Use good, viable, certified seed.
- Planting methods are drilling, broadcasting, transplanting and vegetative.
- Seeds to sow = plants wanted ÷ germination fraction.