Vegetables

Background

Climatic requirements

Soil requirements

Fertilization

Irrigation

1. Cabbage

Botanically referred to as Brassica oleracea var. capitata L. is a versatile crop that can be consumed raw, cooked or boiled. Cabbages are very healthy, they are high in vitamins and minerals, particularly vitamin C.

Cabbages thrive under cool weather and are frost tolerant. They can germinate in soil temperature as low as 4°C, whereas the optimum temperature is 18°C -35°C. The ideal growth temperature for cabbage is 18°C, the maximum being 24°C.

Well drained loamy soils that have been well prepared and can allow root penetration of 600mm

Nitrogen: 180-250Kg/ha

About 70-90Kg/ha applied to the soil before planting

Phosphorus: 50Kg/ha before planting

Potassium: 120-180Kg/ha before planting

pH: 6-6.8

Soil dressing: Limestone Ammonium Nitrate (LAN)

The total amount of water required is roughly 400mm

2. Okra

Sometimes called ‘lady’s finger’ or ‘gumbo’, okra is of economic importance in most African countries. The seed pods are mostly green and can be about 3 to 5 inches long at harvest

Okra does not thrive in low temperature and is not tolerant to frost but is resistant to drought. It grows well in warm temperatures with minimum temperature of 22°C and maximum of 35°C

Light well drained sandy-loam soil that is rich in organic matter. Ridges are ideal for planting.

pH: 5.8-6.8

Average annual rainfall for optimum growth and yield is 1000mm. Only irrigate when necessary.

3. Spinach

Botanically referred to as Spinacia oleracea, it is a herb that is grown annually. Spinach is an easy to grow vegetable, it has green leaves that are oblong-shaped and can be smooth or crinkled.

Growing periods are from January to April where it is not too hot or too cold, and from August to December when summer temperatures have not reached peak.

Check soil moisture twice a week.

Between 500Kg and 1000Kg of Nitrogen, Phosphorus and Potassium should be applied at soil preparation in the ration 2:3:2

250Kg of LAN after 5 weeks and again after 8 weeks of planting.

Irrigate after planting and after germination.

4. Tomato

Tomatoes originated in Central America and have the scientific name Lycopersicon esculentum, they belong to the Solanacea family. They is herbaceous, most grown for their edible fruits, they are rich in lycopene and offer several health benefits.

Tomatoes are a warm season crop, they have an intolerance to extremely low temperatures. For optimum growth of tomatoes, the temperature should be kept stable with less variations between the minimum and the maximum as possible. Ideal average temperature is between 26°C- 29°C, with the minimum and maximum being 10°C and 34°C, respectively.

The soil must be very fertile. Soil should not be compacted and should allow for adequate root penetration of 600mm. Organic matter is important to improve soil quality.

Nitrogen: 180-200Kg/ha require in high amounts during the first 5 weeks of vegetative growth.

Phosphorus: 60-100Kg/ha

Potassium: 300-300Kg/ha for flowering from 6-12 weeks

Calcium: 250-300Kg/ha and Magnesium 50-60Kg/ha for fruit set at 12-20 weeks.

Drip and flood irrigation are recommended instead of overheard irrigation to prevent foliar diseases. In cool seasons 25mm of water per week and 50mm per week during very warm and windy seasons.

5. Onion

Come from the Allium family. Onions are important commercial crops globally.

Onions are a cool season crop but can be grown throughout the year in South Africa. From February to April in the Northern region, April to July in the central region and from July to October in the Southern region. For germination, soil temperature should be between 11-25°C while for growth 22-28°C is ideal.

Soil with good water drainage is ideal for optimum growth. Upper layer of 75cm in depth should be loose and raise beds to manage waterlogging.

Nitrogen: 180Kg/ha, 60Kg/ha applied before planting, 60Kg/ha when leaves emerge and 60Kg/ha at 4 weeks.

Phosphorus: 100Kg/ha applied before planting

Potassium: 170Kg/ha.

110Kg/ha before planting and 60Kg/ha 7-8 weeks before harvesting.

pH: 6-6.8

At least a depth of 50cm-60cm should be wet. Soil type, irrigation system used, temperature and crop growth stage determine the quantity of water required.

Background

Climatic requirements

Soil requirements

Fertilization

Irrigation

1. Maize

Scientific name is Zea mays L. Maize is the number one most important grain crop in South Africa and is the staple food crop.

Maize is a warm season crop that can be grown in different environments. The average temperature should not go below 19°C, while in summer it should go below 23°C. Maize is intolerant to frost, 120 to 140 frost free days are required to prevent damage. Soil temperature should be 16- 18°C for germination. Maximum temperature is 32°C.

Sandy soils with no more than 10% clay or clay-loam soils with 30% excess. Soil in texture classes between 10% and 30% clay have good air circulation and moisture that is ideal for maize production. Good water drainage and soil depth is also essential for optimum growth.

Nitrogen, Phosphorus and Potassium (NPK) should be band-placed 50mm to the side and 50mm below the seed at planting. For 0.9m, 1.5m, and 2.1m rows application should not be more than 70Kg, 50Kg and 30Kg respectively. Zinc can be applied as a micro-element.

One plant can use about 250L of water from planting to maturity when there is no water stress.

2. Sugar beans

Sugar beans are always in high demand because they are enjoyed by most households as well as institutions like schools and prisons.

Sugar beans are warm season, annual crops. The ideal temperature is 18°C to 24°C for growth and not more than 30°C during flowering. Minimum soil temperature should not be below 13°C.

Soil depth of 90cm that is well drained and rich is nutrients is recommended. Soil type can be sandy loam, sandy clay loam or loam with clay content of 15-30%.

Sugar beans should be planted in soil that has been previously adequately fertilized. It is recommended to use Compound D (7:14:7) basal fertiliser, ammonium nitrate can be used as a top soil dressing.

Sprinkler irrigation can be used. Irrigate to field capacity before planting (depth greater than 60cm). for germination and emergence, 30-40cm of water is required. Avoid irrigating on flowering crop (irrigation should take place before).