admin
Kennedy Mabehla
Correspondent
Sunflower has become a very important oil seed crop, due to its drought tolerant properties which enable it to be grown under varying soil and climatic conditions.
Due to its big production capacity and high value over the years, sunflower cultivation has become popular across Southern African region.
Sunflowers are a drought resistant crop that can produce high yields on as little as 410 mm of rainfall provided the soil is moist just before and during flowering period.
Sunflowers are suited to region II and region IV and will earn more than maize in these areas.
They are mainly planted from mid-December to mid-February. Yield levels average between 1.5 tonnes per hectare with the November plantings and 0.5 tonnes per hectare with the end of January to February plantings.
Sunflower can grow on any type of soil ad also soil having controlled pH range and saline soil up to some extent.
However, sunflower crop thrives their best in deep loamy soil with an availability of good irrigation and drainage.
Sunflower is not highly sensitive to soil pH.
The crop is grown commercially on soils ranging in pH from 5.7 to over 8.
The optimum depends upon other properties of the soil; no pH is considered optimum for all soil conditions. The 6.0 to 7.2 range may be optimal for many soils.
When considering planting sunflower, farmers should make sure they have adequately prepared their lands.
Poorly prepared fields may lead to soil erosion, poor germination, weed infestation and harvesting losses.
In preparing the seed bed, land must be ploughed, disked and harrowed if necessary to obtain a fine tilth.
Care must be taken with virgin land or heavy soils, where large clods may then cover seeds reducing emergence.
In some instances, it may be necessary to first deep plough the lands before coming in with a disk to break the big clods and have a fine tilth which allows for easy emergence of the seed.
This will ensure incorporation of crop residues and weeds will be turned under.
A fine seedbed for planting will be produced.
If some weeds have come up before planting, either disc lightly or plant and then burn off the green weeds with glyphosate mixed with pre-emergent grass and broad leaf herbicides in one tank mix.
A light disc or spike harrow may be used to break clods to produce a smooth seedbed just before planting if necessary.
On previously cropped fields the soil should be disked preferably after soaking rain.
Sunflower seeds are sown by the dibbling and furrow method.
With the dibbling method, one can sow about 5 to 7 kg of sunflower seeds per hectare land.
Whereas with the furrow method, it is possible to plant about 10 kg of sunflower seeds per hectare.
In regions which receive high rainfalls (regions I, II, III) a spacing of 90x 25 cm is recommended whilst in region IV and V a spacing of 90x 30 cm is also recommended.
Planting lines can be made by opening a shallow furrow with ripper tyne.
The seed should be planted 4-5 cm deep. When seedling appears, excess seedling should be thinned after two weeks of the seedling.
Also, a proper seed treatment is to be carried out for better germination of sunflower seeds so, that you can achieve a good plant density.
Planting depth is critical. In sandy or light soils seed can be placed up to four centimetres (cm) deep.
In heavy soils (high clay content) a depth of two — three cm is adequate.
If planted too deep, sunflower seed will fail to emerge. If it rains soon after planting, a crust may form that will hinder germination.
A light spike harrowing across the rows will aid germination.
Dribble basal compound fertilizer into the furrow at 150—250 kg hectare.
In fertile soils or previously well-manured, fields previously planted to well-fertilised maize crop use less basal fertiliser. One handful should be dribbled on one metre length to give approximately 150kg per hactare.
l Kennedy Mabehla, Agritex Principal Agronomist
Online Reporter