Maize

Introduction

• Scientific name: Zea mays
• Family: Poaceae
• Common name: Corn, Maize
• An erect, fast-growing, short-lived annual growing to 7 m, but more commonly to 2-3 m in height.
• Female flowers ( ears) arise from axillary bud apices and Male flowers (tassels) arise from the apical stem.
• Conventional roots are supplemented with aerial brace roots, which protect against lodging.

Use

• As a forage, is normally green-chopped or made into silage before being fed to animals or conserved as hay.
• Makes excellent silage due to its high yields and no requirements for additives to assist the ensiling process.
• Stover from corn grown for grain is a major source of feed for ruminants.

Soil requirements

• High nutrient demand for optimum growth and responds strongly to fertilizer when grown on infertile soils.
• Adapted to well-drained soils of neutral to mildly alkaline reaction, but will grow down to pH 5 providing that aluminum saturation is low.
• Has low to moderate tolerance of soil salinity.

Moisture and temperature

• Grows best in 600-1500mm rainfall and has very high requirements for water.
• Not drought resistant but will tolerate temporary dry conditions when young.
• Requires a soil temperature of 12⁰C for satisfactory germination and seedling vigor, but 33/18⁰C can be suitable for optimum growth.
• Can grow up to 4000 masl in the tropics but prefers <2,400 masl.

Reproductive development

• short-day or neutral-day plant, maturing in 90-120 days but as quickly as 80 days with very short season cultivars.
• In high altitudes, may take over 6 months to flower.
• Monoecious, wind-pollinated plant.
• Self-pollination is possible, but wind promotes cross-pollination.

Defoliation

• Will tolerate defoliation during early growth, but seasonal leaf and grain yields may be reduced where rainy seasons are short.
• For silage production, should be cut in the medium dough stage when the grain is full.

Establishment

• Requires a well-prepared seed bed and is often planted into raised beds.
• Seeding rates vary from 25000-75000 plants/ha. ( 4-12 kg/ha seed).
• Bed/row spacings range from 75-120 cm apart and seed is planted 50-100 mm deep depending on soil type and moisture.
• Sown in spring through to mid-summer in the subtropics and at the break of the wet season in the tropics.

Fertilizer

• Applied at both pre-plant and as side-dressings to achieve high yields.
• Requires 80 kg N, 40 kg P, and 40 Kg K per hectare for rain-grown crops.
• Attention to weed control is essential until canopy closure.

Nutritive value and palatability

• Maize silage is high in metabolizable energy ( 9-12MJj/kg DM) but relatively low in crude protein ( 7-8 %).
• Digestibility can be increased by the addition of urea or molasses.
• Highly palatable to ruminants as a green feed, silage, or as hay.

Toxicity

• Lactic acidosis can occur if moderate to large quantities of grain, such as corn, are fed to ruminants not yet adapted to grain diets.
• Mid-cases cause dehydration and loss of appetite, whereas serious cases result in acidification of the blood causing heart failure, kidney failure, and death.
• Livestock should be gradually introduced to a high-grain diet over 3 weeks to prevent the risk of acidosis.

Dry matter

• Produce 15-25 tonnes of DM with 10-12 MJ/Kg DM of metabolizable energy within 4-5 months if correctly managed.
• Maize grown in the tropics generally produces a larger number of leaves and is generally leafier than temperate-grown maize.
• At 50% of total DM intake, cattle growth rates of 0.6-1 kg/head/day can be expected.