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Lesson Note

Subject: Agricultural Science
Topic: Husbandry of Selected Crops (Maize)
Lesson Objectives: At the end of the lesson, learners should be able to:

  1. Explain how various crops are produced,
  2. State the different classes of crops planted,
  3. Explain the production process of Maize.

Lesson Discussions

Classification of Crops:

Crops are plants that are grown by man with intention of being harvested. The crops are usually classified on the basis of their products and type into:
i. Cereals: maize, rice, guinea corn, millet, wheat, etc
ii. Pulses (Grain Legumes): cowpea, soyabean and pigeon pea.
iii. Stem and Root tubers: cassava, yam, cocoyam and sweet potato.
iv. Vegetables: tomato, onions, okra, spinach, cabbage, lettuce and amaranthus.
v. Fruits: citrus, banana, pineapple, mango, guava and pawpaw.
vi. Beverages: cocoa, tea and coffee.
vii. Spices: ginger and pepper.
viii. Oils: groundnut, oil palm, melon, coconut and shea butter.
ix. Vegetable fibres: cotton, jute and sissal hemp.
x. Latex: para-rubber.

Production of Maize (Zea mays)

Scientific Classification

Origin: It is believed that maize originated from Central and South America and came to West Africa in the 16th Century.
Varieties: There are a number of varieties mainly distinguished by endosperm characteristics. The relative thickness of the pericarp to the endosperm determines the quality of the maize fruit.
i. Sweet maize: The grains contain a glossy sweetish endosperm which is translucent when immature and dries to give a wrinkled appearance.
ii. Dent maize: The sides of the grains have corneous endosperm, but soft white starch extending to the apex, shrinks on drying to produce a dent.
iii. Flint maize: The grains consist mainly of hard endosperm with a little soft starch in the centre. The grains are usually small and have rounded ends.
iv. Flour maize: The grains have no dent and the endosperm consists of soft starch.
v. Popcorn: These have small grains with a high proportion of hard endosperm with a little starch at the centre. The grains explode or pop on heating to produce a palatable white fluffy mass.

Varieties of Maize

Uses: Maize serves as a staple human food, livestock feed and raw materials for varied industrial products e.g corn flakes, semovita, alcohol (beer), etc.Ecological Requirements: It grows in a wide range of soils but loamy soil is the best. It needs well-drained deep soil that is optimally aerated. It has a high water requirement and does best where there is about 400mm of rainfall that is evenly distributed. Maize also tolerates a slightly acid to neutral soil condition of pH 6.0 – 7.0 and a moderate temperature.Land Preparation: Clear the land and till the soil to a shallow depth of about 22cm. In a virgin soil, there is no need for tillage.
Method of Sowing: Maize preparation is by planting the grains (fruits) in situ. It does not require any nursery preparation.
Sowing: Sow 2 – 3 seeds per hole to a depth of about 4cm. Treat the seeds with Aldrin 2.5% dust before planting to prevent pest infestation.Time of planting: In Northern Nigeria, Ghana, Gambia and Sierra Leone, planting is in May/June but in Southern Nigeria and Ghana, early maize is planted in March or April while late maize is sown in August or September.Spacing: When handsown, a spacing of 45 – 60cm along the row and 90cm between rows is recommended. If maize is drilled, the spacing should be 25cm by 75cm.

Seed Rate: The amount or quantity of planting material (seeds) used per area of land is called the seed rate. An average seed rate of 16kg/ha is usually recommended and this gives a stocking density of 35,000 plants per hectare.Fertilizers Requirements: Fertilizer recommendations are related to local soil conditions but generally a split application of NPK (15:15:15) at 2 – 3 weeks after planting and 2 weeks before tasselling is applied. Apply the fertilizer in a ring of about 10cm radius and to a depth of 3.0cm round each plant. In sandy areas the fertilizer requirement is a mixture of 112kg/ha of nitrogen, 82 kg/ha of phosphorus, 45kg/ha of potassium and 112 kg/ha of magnesium. Apply fertilizers after weeding to reduce competition for nutrients between the crops and the weedsWeeding: This is usually manually done although chemical weed control with 2.4 – D. Atrazine, Simazin etc is being increasingly used.Harvesting: Maize crops mature in three months. Maize ears are harvested when the leaves turn yellow, the husks turn tell and dry and the grains become hard. In hard harvesting, the cobs are broken off with as little attached stalk as possible, the cobs can be snapped from the stalk with the husks still attached or removed. In mechanical harvesting, a corn picker is used to pick the ears, remove the husks and shell the grains in a single operation. Where maize plants are grown for livestock feeding, the ruminants might graze on them directly or be fed with cut succulent maize materials as soilage.Storage: The ears may be tied together and hung-over the fire place. The dried grains may be stored in air-tight containers or in cribs. Grains may also be stored in jute bags with appropriate protectant insecticides such as phostoxin and aldrex-T.Marketing of produce: Maize grains may be sold in local markets or to Nigerian Grains Board or to brewing industries in Nigeria.Pests: The main pests include birds, stem borers, earworms, cut worms, weevils, rodents and monkeys.Diseases: Maize rust, smut, streak, leaf spot and blight are the major diseases

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  1. Explain how various crops are produced.
  2. State the different classes of crops planted.
  3. Explain the production process of Maize.

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