admin
Kennedy Mabehla
Correspondent
Soyabean production should be increased to boost oil production. This will reduce the import bill.
Last year, soyabean production stood at 70 000 tonnes against demand of 220 000 tonnes.
The industry has capacity to process 560 000 tonnes market available.
Farmers should grow soyabean following correct agronomic practices for higher yields.
Planting
Plant your soyabean crop within the optimum planting window, with the right variety and fertilisers to increase your yield potential.
Plant a soyabean hectarage in line with the inputs at hand. Spreading inputs on the wider area will not necessarily give better returns.
The optimum planting window for maximising yield potential is between November 15 and early January.
Sowing soyabean with the first effective rains is critical as it affects yields achieved.
Farmers should therefore make all the necessary preparations ahead of time.
Planting soyabeans in rows makes weeding and harvesting easier thereby saving labour and reducing costs.
Rows can be dug out just before or during planting depending on the machinery.
Planting soyabean in rows 45- 60 cm apart and 3-5cm within a row should give you the optimum plant population of 300 000plants/ha for rainfed crops.
Use 100 to 120kg of soyabean seed per hectare that is planting 20 to 30 seeds per linear meter of furrow and two seeds per hill. Aim to achieve 250 000-300 000 plants per hectare.
If using a planter, ensure the seed plate is right for soyabean, it is well-calibrated and spaced well to achieve the desired population. Using animal-drawn planters, can save the farmer time, labour and money as they can apply basal fertilizers, plant the seed and cover in one pass.
Plant soyabean by first opening planting furrows using ox-drawn cultivators or hand-hoes then sow the seeds into the furrow.
Use the plough yoke to open 45cm inter row soyabean planting furrows. This gives optimum plant spacing and plant population.
The cart yoke (60cm) maybe used to open inter row furrows and decrease the in row to spacing to 3cm to get optimum plant population.
Make decisions on whether you want to adopt conservation farming or go for conventional tillage. Ask your local extension worker on pros and cons of each.
Soyabeans can be effectively grown using conservation agriculture to save on labour, fuel and time.
Following direct seeding or planting, you should apply appropriate herbicides within three days after planting.
It is important to read and follow precautionary measures as indicated on the herbicide container labels before using herbicides.
Consider seed dressing before planting soyabean to ensure uniform stand emergence and desired population, to help achieve maximum yield.
Seed dressing with appropriate fungicides is cheap compared to the potential cost of having to replant due to a stand failure.
Soyabean should not be dry planted and should only be planted until it is clear that the rains have properly started.
Plant soyabean in soils holding adequate moisture for germination. Plant in dry soils only if you can supplement with irrigation soon after planting.
Late planting may expose the crop to attack by some late season pests and also deprive the crop of sufficient moisture if the rains stop early. White ants or termites and soil crickets should be treated at planting time.
Soyabean requires cotton fert (cpd L) (NPK5:17:10) or potash blend (NPK 5:12:28) at the rate of 200-300 kg/ha before or at planting.
Also apply fertiliser by banding fertiliser at least 1,5kg Compound L/100m in a furrow if you are aiming to apply 300kg/ha.
Compound D can also be used as a basal fertiliser in soyabeans, but does not contain boron which is required for good oil formation in the seeds.
Where phosphate and potash are low, a pre-plant application of muriate of potash or single super phosphate is advisable.
When growing soyabeans on a field for the first time, innoculate with nitrogen-fixing rhizobia to enhance your yields.
At planting, make sure the inoculated seed must not get in contact with fertilizers because the fertilizer may kill the bacteria.
Properly inoculated soyabeans will have an adequate supply of nitrogen from the root nodules from about three weeks after planting until harvesting.
An 100g Rhizobium inoculant satchet is adequate to treat 100 kg of seed to plant one hectare of soyabeans.
If Rhizobium inoculant is not used, it costs between US$66- $80 to top dress a hectare of soyabean with ammonium nitrate (AN) fertilizer
Soyabean inoculants require careful handling and storage. When you have inoculated your soyabean seeds, planting should be done the same day.
In the event of leaching and water logging apply up to 100kg per hactre ammonium nitrate on sandy soils and 50kg per hactre on heavy soils prior to flowering.
Weeding
Soyabean yield reduction is mostly due to weed competition occurs during the first six weeks after planting; keep your crop weed free during this critical period.
Carry out the first weeding at two weeks after planting and the second at 5–6. Hand hoe or use a cultivator to maximise the yield potential of your soyabean.
Be aware of some of the troublesome weeds in soyabean fields, which include the Shamva grass, Couch grass, Black Jack, Chowa, and Chaarendo.
Weed control should begin with burn down before planting and continue throughout the growing season and following harvest. Weeds can significantly decrease soyabean yields and sharply increase input costs if not controlled timeously.
If you intend to use herbicides, you should look at the target weeds and the cost of the herbicide per unit area.
Avoid weeding immediately after rains, you might just be transplanting the weeds.
Any delays in weeding may cause significant reductions in soyabean yields.
Use an animal drawn cultivator or hand hoes to remove weeds at an early stage and leave them to dry on top of the soil.
Late season weeds can result in inefficient equipment operation and excessive harvest losses. Make sure your crop is weed free right from the beginning.
Remember a good stand of soyabeans can help reduce weed competition by emerging rapidly and shading the weeds, thereby reducing competition for sunlight.
You can effectively control weeds at planting by applying a pre emergence herbicide, you may need only one weeding may be required after 5–6 weeks.
Buy a herbicide or combination of herbicides, which will enable you to control the most common and troublesome weeds in your field.
Herbicide use
When using herbicides, use the full labelled rate for all herbicides you apply. Spray before weeds can propagate and produce seed.
It is crucial to always read and follow precautionary measures as indicated on the herbicide container labels before using herbicides.
Also consult your local Agritex staff on calibration your knapsack sprayer to release optimum quantities of herbicides and fungicides. Over application of herbicides may lead to crop burn, whilst under application may lead to poor control and loss of money.
When spraying herbicides about 12 loads water of a 15-L sprayer will be adequate to cover 1 hectare.
Irrigation at planting or three to four days later stimulates rapid germination and prevents possible crust formation.
Make an effort to control the weed seedlings when the crop is 5 to 10cm tall by using a rotary hoe, harrow, or cultivator as soon as they emerge. If you have irrigation facilities, make sure to apply water during late grain-filling stage as shortage during this period can drastically reduce yields.
l Kennedy Mabehla is an Agritex Principal Agronomist
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