- INTRODUCTION
Demand for soya beans in world markets has increased considerably during recent years and production in most producing countries is expanding to keep pace.
The soya bean plant is an herbaceous summer annual legume with upright spreading branches. The self-pollinated flowers are generally white or purple and are borne in clusters on the branches. The pods are covered in fine grey or brown hairs and bear 2 or 3 seeds per pod. The seeds are generally yellow but may vary from green to brown to black depending upon the variety. The plants mature in 70 – 170 days depending on the cultivar.
Soya beans can be grown for seed, hay, green manure or silage. The protein content of the seed varies from 36 to 42% and the oil content from 17 to 22%. Low protein content is usually associated with high oil content and vice versa.
There are a number of ways in which growing Soya beans can benefit the farmer. Soya beans, being a short season crop can be grown after maize leaving more time available for harvesting the maize crop and ploughing the land. Alternatively, early planted soya beans can be reaped in March allowing the land to be ploughed early when still moist making for easier ploughing, moisture conservation and a better tilth for the following crop.
Soya beans are an ideal crop to grow in the summer when irrigated wheat is being grown in the winter. They can be harvested in good time to allow the land to be prepared and the Winter wheat sown.
Because soya beans are a legume they improve both the fertility and structure of the soil and leave nitrogen behind in the soil which can be used by the following crop. They also use up any fertiliser nutrients left over from the previous crop and some farmers apply extra fertiliser to their maize or Winter wheat so do not apply any fertiliser to the following Soya bean crop. A maize/Soya bean or Soya bean/Winter wheat rotation will gradually build up fertility over a number of years and, in the long-term, will reduce the fertiliser requirements of the farm.
Climatic requirement of soya beans are similar to those of maize. A rainfall of 550 – 700 mm over the growing season is required. Soya beans can survive short drought periods better than maize.
- VARIETIES
Two groups of varieties are available for commercial use. The first group is a determinate variety which includes PAN 1583R, PAN 1664R and PAN 737R. Varieties in this group have relatively early-to- medium maturity with upright growth habit and high seed-yield potential. The second group is an indeterminate varieties which include A5409RG and PAN 1454R.
SEED VARIETIES A5409RG
This variety flowers 62 days from planting and matures in 134 days. It has a maturity grouping (MG) of 5.5 with an indeterminate growing pattern.
It has an excellent standability with a very good shattering resistance rating. Recommended plant populations are 300 000 for early plantings and 500 000 plants for later plantings or narrow rows. This is South Africa’s first round-up ready variety.
PAN 1454R
This variety flowers in 50 days from planting and matures in 124 days. It has an indeterminate growth pattern with a maturity grouping (MG) of 4.4 and means it is better suited for production in the cool Highveld areas and is not suited for warm areas. It is a good option of soya bean and wheat rotations and has a high oil content. It has a very good standability and shattering resistance rating. Plant populations of 300 000 for early plantings and 450 000 for later plantings or narrow row spacings.
PAN 1583R
PAN 1583R is best suited for the cool and moderate production areas which is similar to the PAN 1664R variety. It flowers 59 days from planting and matures in 131 days and has determinate growing pattern with a maturity grouping of 5. It is short in stature and was developed for high populations. It has an excellent standability and shattering resistance rating. At early plantings a plant population of 350 000 is recommended and at later plantings or narrow row spacings a population of 550 000 plants is recommended. This is an all-round variety that does well in overall production areas.
PAN 1664R
PAN 1664R flowers 60 days from planting and matures in 135 days. It has a maturity grouping of 5.9 and has a determinate growing pattern. This variety has a wide adaptability and producers good yields in the cool, moderate and hot regions. It has an excellent standability and shattering resistance rating. Plant populations should be 300 000 plants for early plantings and 450 000 plants for later plantings and narrow row spacings.
PAN 737R
PAN 737R has a determinate pattern with a maturity grouping of 7. It is best suited for the warm productions areas but can do well in the cooler regions. It is suited for both dryland and irrigation systems. It flowers 62 days from planting and matures in 142 days. It has a very good standability and shattering resistance rating. A 300 000 plant population is recommended at early plantings and 400 000 plants for later plantings or narrow rows.
- REQUIREMENTS
Soya beans thrive in areas of good rainfall or where irrigation is available. Soils must be deep and well drained varying in texture from sandy loam to clay loam. Heavy clay soils will also produce good crops provided they are well drained and germination is not impeded by soil capping. Rooting depth is 1.2 m but most roots are in the top 600 mm of soil. Soils should not have a pH of below 5.2 as this impedes nitrogen fixation.
The crop is very sensitive to day length and varieties selected for certain areas may not perform similarly elsewhere.
Seed quality can be severely affected by temperature and moisture. There is evidence that late rains during the growing season or high temperatures can drastically reduce seed viability. All seed should be germination tested before planting.
- FERTILIZATION
Soya beans are best grown on the heavier-textured soils with a slightly acid-to-neutral reaction and a good organic matter status. Although fairly substantial amounts of nitrogen, phosphorus and
potassium are removed from the soil the crop does not generally respond to direct fertilization except on a soil of low fertility. However, there is evidence to suggest that indirect fertilization is more effective. In other words if the rotation as a whole receives adequate amounts of fertiliser, little or no fertiliser need be applied to the Soya bean crop.
Although Soya beans are legumes, local experience indicates that nodulation does not become effective until 5 or 6 weeks after germination whereas the nitrogen stored in the seed is exhausted within 2 or 3 weeks of germination. In most cases it is therefore desirable to apply a small starter application of fertiliser nitrogen.
Where it is considered necessary to apply fertilisers directly to the crop, the nitrogen, phosphorus and potassium requirements of a particular land are most reliably assessed by soil analysis and farmers are strongly recommended to have samples from their lands analysed regularly. Failing this a rough assessment of the probable requirements can be made from what is known of the past history of the land and the fertiliser treatment it has received.
The table below gives the average requirements of nitrogen, phosphorus and potassium for soils that are likely to have good, medium or poor status in respect of the major nutrients. This is followed by short notes to enable farmers to decide in which of the three categories their soils are likely to fall. It is assumed that all crop residues are to be returned throughout the rotation.
Table 1: The average nutrients requirements of Soya beans
| Fertiliser | Nutrient Status of Soya beans | ||
| Nutrient Status | Good | Medium | Poor |
| Kilograms per hectare of fertiliser nutrient required | |||
| Nitrogen | Nil | 10 – 20 | 10 – 20 |
| Phosphorus | Nil | 20 – 40 | 40 – 60 |
| Potassium | Nil | 20 – 40 | 40 – 60 |
NITROGEN STATUS OF THE SOIL
Good: Following a good leguminous green crop turned-in at the correct time and stage of maturity and lands that have regularly received heavy dressings of compost or manure.
Medium: Early-ploughed virgin or reverted land and grass leys and cultivated lands. The higher rates should be used on lands where cash crops are grown continuously and crop residues are returned.
Poor: Late-ploughed virgin or reverted lands and grass leys.
PHOSPHOROUS STATUS OF THE SOIL
Good: Cultivated lands on which a large amount of fertiliser phosphorus has been applied in the past by means of regular uninterrupted annual dressings.
Medium: Cultivated lands on which a moderate amount of fertiliser phosphorus has been applied in the past.
Poor: Virgin or reverted lands on which little or no fertiliser phosphorous has been applied n the past.
Figure 1: Phosphorus deficiency in the plants on the right of picture, no clear symptoms but the leaves and plant are smaller than normal.
Source: soybeansoilfertility
Figures 2 and 3: Potassium deficiency, the outer edge of the leaves turn yellow and move inwards
Source: cmegicmlebanon.blogspot Source: extension.missouri.
METHODS AND TIMES OF APPLICATION
The whole of the nitrogen, phosphorus and potassium requirements should be applied in the form of straights or compounds at or before planting. The fertilisers should be broadcast and diced-in as deeply as possible after ploughing.
LIME REQUIREMENTS
Soya beans are very sensitive to soil acidity and for maximum yields the calcium-chloride pH value of the soil must be above 5.2. It is essential to correct the pH of the land by adequate applications of lime where necessary but this should only be done on the basis of a soil analysis.
The lime may be applied at any suitable stage in the rotation and may be applied immediately before planting. When applied immediately before planting it must be broadcast and diced in deeply preferably after ploughing.
Figure 4: A crop of soya beans growing well
Source: aviewfromthecab.wordpress
PLANTING
Legumes are symbiotic with certain bacteria which fix atmospheric nitrogen for the growth of the plant. The bacteria Rhizobium spp., are normal inhabitants of the soil and infect the roots of legumes to form nodules in which nitrogen fixation occurs. Nodules can be distinguished from eelworm galls as they are always attached to the side of a root whilst the galls are swellings of a root itself. The bacterium Rhizobium japonicum is responsible for forming nodules on soya-bean plants but does not normally occur in the soil and seed and must therefore be inoculated. Effective nodules are pink inside while non-effective nodules are white. Successful fixation can be achieved with only a few large nodules on each plant.
Nodules become operational 4 to 6 weeks after planting depending upon conditions of soil moisture. An initial
application of 10 – 20 kg/ha of nitrogen provides for the early growth. There is evidence to show that more nitrogen than this does not increase yield and can reduce it. Yield is drastically reduced if seed which has not been inoculated is planted into soil which does not contain residual bacteria. Very wet soil conditions can delay nodule formation by 6 to 8 weeks giving the plants a typical nitrogen-deficient appearance. There is evidence to suggest that between 100 and 150 kg/ha of nitrogen would be required to give the same yield as a well-nodulated crop.
Following a successfully nodulated crop bacteria can survive for 2 years in sandy soil and up to 4 years in clay loams.
Successful inoculation is achieved by treating the seed immediately before planting and allowing it to dry in the shade protected from the sun. Care must be taken to apply only sufficient water to wet the seed without damaging the seed coat.
There have been cases of complete germination failure caused by rotting of the seed and seedlings before emergence. This can possibly be prevented by treating the seed with a non-mercurial seed dressing, e.g. Captan, Thiram, at the time of inoculation.
The date of planting is generally determined by the weather conditions expected at reaping. High yields are achieved by early planting but can be at the risk of severe losses as a result of late rains. Soya beans must be reaped within a short period after having reached maturity and before they shatter. Should rain fall during this period reaping may be delayed and losses will consequently occur.
Temperature and altitude effect growth in such a manner that the planting date occurs earlier in the higher-altitude cooled areas, than in the lower warmer areas. Planting dates at different altitudes must be adjusted so that the crop will mature from mid-to-late March. Suggested planting dates are set out below:
- Hot Regions – Bushveld and Lowveld
Planting dates are from the end of November to the end of December.
- Warm Regions – North West, Northern Province, Northern KwaZulu-Natal and Northern Free State
Planting dates are from the middle of November to the middle of December.
- Cool Regions – Southern KwaZulu-Natal, Eastern Free State and Eastern Mpumalanga Planting dates are from the end of October to the end of November.
The time of planting is also influenced by the other crops being grown and weather conditions on the proposed planting date. All long-season crops must be planted earlier than the short-season crops but a date must be set after which only the latter should be planted. The short-season crop may be planted a week or so before the proposed planting date if good rains permit but only after all the long-season crops have been planted. Any delay in planting could result in a much longer delay waiting for further planting rains and might continue until after the optimum planting date has passed.
Figures 1 and 2: A planter planting soybeans into the old crop residue
Source: kruger.morganmyers Source: ryancramerforyetter
ROW SPACING
Research has shown that top yields will be achieved when rows are spaced 450 mm apart. Considerations such as tractor access for cultivation and insect control and the time taken to alter tractor wheel spacing for the other crops grown will determine the most suitable spacing.
Wider spacing appears to reduce yields of late-planted crops but depends on conditions and cultivar choice. Narrow spacing encourages taller growth and pods are borne higher off the ground and harvesting losses are less when the crop is reaped by combine harvester. Good yields can be achieved provided soya beans do not lodge; no disease develops in the dense leaf canopy and good weed control is practiced. Additionally a canopy develops earlier thus reducing weed competition.
Wide row spacing will produce plants which carry pods closer to the ground, but if the crop is to be cut with sickles the wider rows will enable greater areas to be reaped per labourer per day.
It has generally been found that crops planted at an average row spacing of 450 mm are difficult to manage. As a result more crops are being planted at row spacings of 600 – 750 mm. Average row spacing can be effectively reduced by planting twin rows 200 mm apart at 900 mm centres with the advantage that tractor access is permitted and the slightly higher yields associated with narrow rows can still be achieved.
Depending on row spacing, plants must be spaced 37 – 77 mm apart in the row to achieve the required plant population.
PLANT POPULATION
Top yields are achieved when the plant population is between 300 000 and 450 000 plants per hectare. Plant population can differ according to different growing conditions. The better the growing conditions the higher the plant population. To obtain a higher population one should choose narrower plant spacing and adjust the inter-row spacing to achieve the desirable plant population. Between-row and in-row spacing combinations obtaining a plant population of 300 000 are shown in the Table below:
Table 1: Spacings and Plant Population
| Row Spacing mm | Inter-row spacing (mm) | Plant population per hectare |
| 450 | 77 | 300 000 |
| 600 | 55 | 300 000 |
| 750 | 45 | 300 000 |
| 900 | 37 | 300 000 |
It is important to know the germination percentage of seed being planted and allowance for this must be made to achieve the required population. More seed will be required when the seed has a low germination rate. Allowance must be made for seed size which can vary considerably from year to year. Seed requirements will vary between 60 and 100 kilogrammes per hectare.
DEPTH OF PLANTING
Seed should be planted 20 to 50 mm deep depending upon soil texture. If the soil is expected to cap, the seed should be planted at higher seeding rates or the rows should be spaced wider apart with plants closer together in the row. The effects of capping can possibly be reduced by using a rotary hoe as early as possible. Since this implement is known to reduce plant population due allowance should be made in the seeding rate
- WEED CONTROL
Weed control is most important if high yields are to be achieved. Since Soya beans are grown as a short-season crop, normally planted after the start of the rains, it is often possible to destroy a crop of weeds before planting. After germination the crop can be cultivated effectively with a millipede provided weather conditions are suitable. This operation is also of value a day or two prior to germination to break any soil crust and assist germination while removing small weeds. A millipede can be used until the crop is 150 mm high.
The ease of weed control in the soya bean crop is affected by the row spacing used. Whilst herbicides used correctly can give extremely good results some mechanical cultivation in the later stages is usually necessary.
The majority of growers would be well advised to use row spacing similar to that of their maize crop and so permit the same cultivators to be used. Closer row spacings appear to give little increase in yield.
Herbicides recommended for use in Soya beans should leave no residue in a following crop.
Figure 3: A tined implement used for inter row weed control
Source: landoll
Table 2: Herbicides available
| Common Name | Sold As | Method of Use |
| Trifluralin | Trif Trifluralin | Incorporate immediately 50 to 100 mm deep prior to planting. |
| On ridged crops, the above herbicides must be incorporated after ridging. | ||
| Bendioxide | Bentazone 480 SL | Apply at crack stage or earlier if weeds are seen. Crop damage will occur if applied later than the above stage of germination. |
| Terbutryne | Igran 50 WP (wettable powder) Igran 500 FW | Apply prior to crop and weed emergence. |
| Linuron | Linuron Afalon | |
| Fluorodifen Alachlor | Preforan Alachlor | |
| Metolachlor | Dual | |
| Paraguat | Gramoxone | Post-emergence. Will kill all plants growth which it contacts. |
Table 3: Grasses
| Itch Grass | This grass occurs only on the heavier soils. Good herbicidal control can be achieved by the use of trifluralin which requires soil incorporation. |
| Crow Foot Grass | These occur on all soil types and are controlled by trifluralin, alachlor and metolachlor. |
Figures 4 and 5: Itch Grass (left) and Crow Foot Grass (right)
Source: invasive Source: wikipedia.
Table 4: Broad-Leaf Weeds
| Pigweed | Easily controlled terbutryne, linuron and prometryne. May be controlled by trifluralin, nitralin, alachlor and metolachlor. |
| Apple of Peru | Control with alachlor, metolachlor, terbutryne, prometryne and linuron. |
| Mexican Clover | A serious problem on some lighter soil areas particularly in a wet season. Trifluralin, alachlor and metolachlor may give some control. |
| Starbur and Wild Hibiscus | Control with alachlor, metolachlor, terbutryne, prometryne and linuron. |
| Blackjack, Mexican Mariglold Gallant Soldier | The most effective herbicides are terbutryne, prometryne and linuron. Alachlor and metolachlor will give some control. |
| Wandering Jew | This weed can be particularly troublesome in the wet seasons. None of the herbicides recommended for groundnuts is reliably effective although metolachlor or alachlor will give some control. |
| Nutgrass | Satisfactory control can be achieved by using alachlor or metolachlor at the full rate recommended for the particular soil type. The soil must be |
Pictures 6 and 7: Broad Leaf Weeds, Buckwheat (left) and Pigweed (right)
Source: ecolibrary. Source: permies
Pictures 8 and 9: Apple of Peru (left) and Mexican Clover (right)
Source: floreznursery.blogspot Source: ricgra_dig1_lr
Pictures 10 and 11: Wild Hibiscus (left) and Black Jack (right)
Source: nams. Source: sbwildflowers.wordpress.
Pictures 12 and 13: Wandering Jew (left) and Nutgrass (right)
Source: ehive Source: patchofweedsinparadise.wordpress
LATE WEEDS PRIOR TO HARVEST
A desiccant herbicide, paraquat, can be used just prior to crop harvest to kill off all green top growth most of which will dry off prior to combining. However, thick weed stalks as sometimes experienced with Pigweed, and Apple of Peru may not dry out in time and would necessitate hand pulling.
After a final light cultivation, consideration can be given to a ‘lay-by’ application of herbicides such as Linuron or Terbutryne to prevent re-infestation by late weeds. Discuss with the supplier.
- DISEASE CONTROL
The expansion of soya bean production will if maintained or increased in South Africa ultimately lead to intensified soya bean disease problems. At present no major disease problems have arisen. Compared with areas of major and long-term production, e.g. America, the number of pathogens affecting soya beans in South Africa is still small. The longer the crop is grown the greater the chance that such a problem will become apparent.
Large areas are presently grown in rotation with wheat so the likelihood is increased by the fact that the crop is grown on the same land each year. This is of far greater consequence to soil-borne diseases than the more obvious foliar problems.
The third factor to be considered is the impracticability of field spraying this crop with the fungicides presently available. Cash return and yield do not warrant repeated fungicide applications so that breeding for fungicide resistant varieties may become necessary.
BACTERIAL BLIGHT
This is the most common soya bean disease present to a greater or lesser degree in every crop. Symptoms are most apparent on the leaves as small dark irregular markings surrounded by a yellowish-green margin. These lesions enlarge and coalesce with age. The leaf eventually becomes ragged and portions drop out. Infection usually starts on lower leaves and progresses up the plant though complete defoliation has not occurred under local conditions. Stems, leaf, stalks and pods may also be affected. Control of Bacterial Blight may be assisted by the following:
- Complete ploughing-in of crop residue after harvest;
- Rotate crops where possible;
- Avoid cultivation of crop whilst foliage is wet; and
- Use disease-free seed.
Figure 14: Bacterial Blight
Source: forestryimages
BACTERIAL PUSTULE AND WILDFIRE
These also attack soya beans though less commonly than Bacterial Blight. Wildfire is able to attack soya beans only through bacterial pustule lesions. It would be unwise to include soya beans in a tobacco rotation since Wildfire is a serious tobacco disease.
Control may be assisted by avoiding tobacco in the rotation.
Pictures 15 and 16: Bacterial Pustule and a close up of the disease
Source: bulletin.ipm.illinois Source: bulletin.ipm.illinois
ANTHRACNOSE
Is most apparent on stems and pods particularly when small black sporing points develop on the infected areas. Young pods are attacked and killed. This disease has caused crop loss in Lowveld plantings.
Control may be assisted by the following:
- Use disease-free seed;
- Rotate crops; and
- Destroy crop debris.
BLUE STAIN (SEED)
Most obvious because of the bluish/purple stain of the seed-coat. The same pathogen can infect leaves and stems. Moist conditions during flowering will result in a higher proportion of stained seed. Severely discolored seeds may adversely affect germination and carry over infection.
Control of Blue Stain may be assisted by the following:
- Use disease-free seed; and
- Rotate crops.
Figure 17: Blue Stain on soya bean seed
Source: forestryimages
LEAF SPOTS
These are a few of the leaf spot diseases found on Soya beans: Ascochyta sojicola, Cercospora canescens, Pyrenochaeta glycines. None have caused serious problems to date apart from defoliation towards the end of the growing season.
Control may be assisted by the following:
- Rotate crops; and
- Destroy crop debris.
Figure 18: Frog eye leaf spot
Source: mississippi-crops
STEM CANKER
Wilting of young plants through basal stem decay. Since this pathogen is present in most soils damage is caused when conditions favour the disease rather than the plant which usually happens in cool wet soils soon after planting.
Control may be assisted by the following:
- Treat seed; and
- Avoid planting in wet cold soils.
Figure 19: Stem canker in soya beans
Source: blog.lib.umn.edu
SCLEROTINIA ROT
Pale tan stem lesions with profuse white fungal growth in which large black sclerotia develop. The latter are also produced within the pith area of the stem. Leaves above the infection wither. The disease develops in groups or patches of plants. This is a potentially serious disease and great care in seed-crop inspection is necessary.
Control may be assisted by the following:
- Plant disease-free seed;
- Plough deeply; and
- Use lengthy rotations with non-susceptible crops.
Figure: 20 and 21: Sclerotinia stem rot (white mold)
Source: corn.osu.edu Source: uwex.edu
NEMATODES
The soya bean is a host to the root-knot nematode Meloidogyne javanica and the degree of galling is sufficient to markedly increase the nematode population. Soya beans should not be grown in a tobacco rotation.
Of the many soya bean varieties tested for susceptibility to M. javanica, not one has shown a degree of resistance to any marked extent. Most varieties become heavily galled and growth suffers accordingly. All varieties tested would cause an appreciable increase in the numbers of nematodes in the soil.
- PEST CONTROL
SEMI-LOOPER, CATERPILLARS
Since an infestation is probably not seen in its early stages the crop should be scouted once a week for the presence of eggs and newly hatched caterpillars. Scouts should be used on stepped traverses in the field. Select 24 evenly distributed sites in the field of 20ha or less. One whole plant is examined for eggs and young larvae at each site. When numbers show a sudden increase allow a week to pass before applying insecticides to ensure that most of the eggs have hatched.
Spray with 1 000 g carbaryl 85% WP (wettable powder) per hectare in a convenient volume of water to which 5% molasses (by volume has been added).
Figure 22 and 23: Cabbage looper larvae (left) and Moth (right)
Source: waggabirds.wordpress Source: .extension.umn.edu
AMERICAN BOLLWORM
Control is the same as for semi-looper caterpillars.
Figure 24: American bollworm
Source: nbaii.res.in
CUTWORMS
Where infestations are expected control with pre-plant baits as follows:
- 120 trichlorfon 50% WP;
- 20 kg maize meal;
- 500 g sugar or 1 kg Molasses; and
- 20 litres of water.
Mix dry and then add water to obtain a crumbly texture and only apply late in the afternoon. These quantities are enough to treat one hectare.
Figure 25 and 26: Cutworm (left) and cutworm damage (right)
Source: entomology.unl.edu Source: highdesertgarden
Spray with:
100 ml of Alpha-Cypermethrin (Magnum Super EC) in not less than 220 litres water per hectare.
SNOUT BEETLES
Control adults with a cover spray of 600 g carbaryl 85% WP in 100 litres water per hectare.
- W.P. Where these letters occur in this lecture they are abbreviations for wettable powder. This is used as a kind of disinfectant.
- E.P. These are letters used in this lecture as abbreviations for emulsifiable concentrates. When mixed with water these concentrates form a milky looking disinfectant.
- HARVESTING
Harvesting is one of the most critical steps in profitable soya bean production. The crop is ready for harvest for seed when the pods have dried out and most of the leaves have fallen off. The best indication of maturity appears when a handful of pods will shatter easily and the ultimate test is to try to shell. Once this stage has been reached harvesting should commence as soon as possible and before the pods begin to shatter. The time taken from planting to maturity varies with the variety grown and the environment.
Varieties presently grown tend to shatter sometime after they mature. Depending on prevailing weather conditions shattering will normally occur 2 or 4 weeks after maturity. The actual time of reaping and the method used will depend on a number of factors all of which should be considered before a final decision is made.
These factors are:
- Hectares planted;
- Variety;
- Weather conditions
- Moisture content of seed (see section of the lecture on the subject of drying);
- Availability of drying facilities;
- Height of pods from ground;
- Presence or absence of weeds;
- Availability of combine harvesters, stationary shellers and hand labour; and
- Weather crop is produced for commercial disposal or for seed.
HAND HARVESTING
This method is suitable for small areas or where a large labour force is readily available. The advantage of hand harvesting is that losses are reduced to a minimum soya beans of high quality are produced and the beans normally have a high germination percentage. Hand-harvesting is suitable for seed producers.
The usual system of hand-harvesting is to allow labourers to cut or pull as much plant material as they are able to thresh in a day. Collection of the plant material must take place early to avoid shattering when the plant is handled. When hand hoes are used care should be taken to cut the plant just below ground level as to minimise shattering.
A labourer should be able to cut and thresh 1 bag of clean beans per day. A variation of this is to use a mower to cut the plant material and use a mechanical windrower for the final cleaning. This method should enable an output of at least 3 bags per labourer per day to be achieved.
Figure: 1 and 2: Hand harvesting, pulling plants out by hand (left) and cutting plants with a slasher (right)
Source: americasfarmers.blogspot Source: .flickr
MOWING OR CUTTING BY HAND, AND SHELLING
This system enables harvesting to commence before the pods are ready but only after sufficient moisture has been lost to prevent moulding in the cocks or stacks. The advantage of this method is that the danger period is avoided during which shattering occurs.
The crop is mowed using an ordinary cutter-bar mower or cut by hand and then windrowed. It is then cocked or stacked until it can be threshed. Since shattering does not occur once the crop is in the cock shelling can be done when convenient. Cocks or stacks must be constructed so that water cannot penetrate them during rainy spells. Using a mower at the wrong time can lead to major loss of soya beans as the seed will be spread all over the land which makes harvesting very difficult.
Most maize shellers that provide bean attachments are suitable for shelling soya beans while tractor-drawn combine harvesters have a low output owing to the low intake rate but alterations to the machine may make an increased output possible.
Figure 3: A Sickle Bar Mower
Source: beavervalleysupply
COMBINE HARVESTERS
Large areas are usually harvested by combine. Losses are inevitable when combines are used. The degree of loss depends on the efficiency of the operator, evenness of the land, lodging, weed control, the height of the pods off the ground and the moisture content.
In order to reduce combine losses, attention should be paid to the following points.
· Land-plane if necessary
Level lands enable the combine to cut beneath the lowest pods. Uneven lands greatly reduce combine efficiency and increase cutter-bar losses and maximise soiling especially when wide cutter-bars are used.
· Ensure High podding
Low podding should not be a problem under conditions of vigorous growth and tick even strands.
· Keep lands weed-free
Before combining hand-pull late weeds which can cause soil staining and threshing losses.
Figure 4: A Combine Harvester
Source: curvingback.blogspot.
Combine output can be roughly estimated by using the following formula: Width of cut (metres) x speed (km/h) = hectares per hour
10
This gives the theoretical value, not allowing for stops or turning time, and assuming a field efficiency of 60 to 70%, depending on field size and conditions. Field tests in the U.S showed that as combine speed increased above 5 km/h, the height of cut rose considerably and also increased losses. At least 60% of all losses can normally be attributed to the combine header.
Close attention must be given to setting cylinder speed, concave clearance, sieves and air blast according to the operator’s manual.
The reel should be positioned with its centre line 300 mm ahead of the cutter-bar and bat speed should be adjusted to about 25%, faster than ground speed. Periodically check for total losses at the rear of the combine. Approximately 60 beans per square metre is equivalent to one bag per hectare. If this check shows a loss of more than 3 or 4% of yield, proceed to pinpoint the main source of loss. The golden rule is, ‘Take it low and take it slow’.
MEASURING SOYA BEAN HARVESTING LOSSES
Soya bean harvesting losses as high as 6 and 7 bags per hectare during combining, have been heard of. On present day average yields, this represents over 20% of the crop. While it is appreciated that inadequate land levelling and poor cultivation practices must often be major reasons for this loss, it has also been shown that a careful and capable operator
can combine soya beans with losses no higher than 1 bag per hectare or 3 to 4%.
Combine manufactures and agricultural engineers in America are currently spending a great deal of time on improving the efficiency of combines for soya beans. It may be some time before the latest of these innovations are available to the farmer. Nevertheless, every combine owner should know just what losses are occurring so as to be able to reduce them as far as possible.
TIPS FOR KEEPING COMBINE LOSSES LOW
- Make sure that knife sections, guards, wear plates and hold-down clips are in good condition and properly adjusted;
- Keep the seed bed level. Do not earth-up soil round plants when cultivating;
- Travel slowly at approximately 5 km/h. To get a rough check on ground speed count the number of ordinary sized paces (0.9 m) in 33 seconds while keeping pace with the combine. Divide the number by 10 to get km/h;
- Operate the cutter-bar as close to ground level as possible always less than 125 mm if possible;
- Use a reel bat speed about 25% faster than ground speed, i.e. for a real diameter 1066 mm use 7rpm for every 1km/h ground speed;
- Reel axel should be 150 to 300 mm ahead of cutter-bar. Reel bats should leave beans just where they have been cut; and
- A six-bat reel will give more uniform feeding.
Acknowledgement: This data was developed by Agricultural Engineers of Ohio State University and modified by the Conex Engineering Branch.
DRYING
To minimise soya bean losses and reduce the probability of damage from weather hazards, harvest as soon as the beans reach maturity. Soya beans can be harvested at 18 to 20% moisture if adequate drying facilities are available. Harvesting at 20% and drying to a safe storage moisture content of 11%, requires the removal of a large amount of moisture and increases the drying cost.
High moisture-content beans lose moisture rapidly in the real field if the weather is favourable, therefore, if weather permits, it is often more economical to allow the beans to reach 16% moisture before harvesting.
- MARKETING
After years of price control by the grain marketing boards, the South African soya bean market was deregulated in the late 1990s after which the South African soya bean producer became exposed to the global supply and demand effects on soya bean prices. To create a South African market that transmits global and local influences into a formal soya bean price, the South African Futures Exchange (Safex) was developed and was bought out by the Johannesburg Stock Exchange in 2001. This futures market by way of the market’s ‘invisible hand’ (Supply and Demand), sets the market prices for soya bean in South Africa.
Farmers, either on their own or through brokers can adopt a number of different strategies depending on their type of operation. The marketing strategies available to the soya bean farmer are described below:
- Harvest and store his crop in co-operative silos for sale when the price is higher than at harvest time. This is the more conventional approach but storage and transport costs need to be taken into consideration;
- Forward contracts agreed pre-harvest, leaving the farmer vulnerable to price fluctuations;
- Harvest and store in on-farm silos which is a flexible but capital intensive option that is normally only available to the large commercial farmer;
- Harvest and store in silo bags, a new method of storage which is cheaper than silos, but not without the risk of loss or damage to the stored grain;
- Hedge his risks on Safex futures and options preferably with the advice of a professional broker. Farmers use this as a hedging mechanism to secure a certain price for a certain amount of their soya bean but do not benefit if the price increases;
- Sell soya bean on the spot market and buy futures. The spot market simply means selling your crop on the day of harvest at the going price on that particular day;
- Use his soya beans as animal feed and sell the animals;
- The ‘one-third’ strategy where the farmer splits his crop between futures contracts, animal feeds and the spot market, thereby spreading his risks; and
- Small-scale growers normally sell their soya beans directly, either through forward contracts with millers or at the spot price to the millers.
Due to government subsidies to farmers in USA and Europe, the global grain market remains extremely volatile and this combined with fluctuating exchange rates and the usual weather anomalies has the combined effect of exposing the unsubsidised South African farmers to a great deal of uncertainty and risk. This stresses the importance of utilising the best possible marketing advice and strategies available to the farmer.
