Crop Husbandry · Agriculture

Husbandry of selected crops

Different crops have their own needs. The summaries below are for the major crops grown in Tanzania.

Crop	Conditions	Planting	Harvest
Maize	Warm, 600–1 200 mm rain, well-drained loams	At onset of rain, 75 × 30 cm, 2–3 cm deep	About 4–5 months; cobs dry, husks brown
Rice	Hot, flooded or irrigated fields, clay soils	Transplant seedlings after 3–4 weeks	When grains are golden, 4–6 months
Beans	Cool, 500–1 000 mm rain, fertile loams	50 × 10 cm, 4 cm deep	3 months; pods dry
Cassava	Warm, drought tolerant, light soils	Cuttings of 25 cm at 1 × 1 m	8–18 months
Cotton	Hot, 600–1 000 mm rain, deep loams	Rows 90 cm × 30 cm	Hand-pick open bolls
Coffee	Highlands, 1 000–2 000 m, 1 000–2 000 mm rain	Transplant seedlings, shade, mulch	Red cherries picked by hand
Tea	Highlands, high rainfall, acid soil	Clonal cuttings, prune	Pluck two leaves and a bud

Harvesting and post-harvest handling

Harvest when the crop is mature, at the right moisture, and handle it gently. Post-harvest operations include drying, threshing or shelling, winnowing, cleaning, grading, treating against pests, packing and storing. In bad storage 20% or more of the grain may be lost to insects, moulds, rodents and moisture. Maize should be dried to 13% moisture or less before storage.

Storage pest	Control
Maize weevil, larger grain borer	Dry grain, clean stores, grain protectants, hermetic bags
Rodents	Raised stores, rat guards, traps
Moulds and aflatoxin	Dry quickly; keep dry and ventilated

m₁ = starting moisture (%), m₂ = final moisture (%).

Worked exampleDrying maize

1 000 kg of maize at 20% moisture is dried to 13%. What is the final mass?

Use the formula.

Answer: About 919 kg.

1 000 kg of grain dried to 13% moisture: the drier the start, the heavier it remains.

Try itDrying grain

Choose the starting mass, the starting moisture and the final moisture.

Check yourself Maize should be stored at a moisture content of about

Check yourself Tea is harvested by

Check yourself Rice is mostly grown

Key terms

Post-harvest: Handling of a crop after harvest.
Threshing: Separating grain from the plant.
Winnowing: Removing chaff by wind.
Hermetic bag: An airtight storage bag.

Summary

Each crop has its own conditions, planting method and harvest signs.
Post-harvest steps are drying, threshing, cleaning, grading and storing.
Store maize at 13% moisture or less.
Good storage prevents big losses.