|
|
|
|
|
surface is uneven or rocky, recovery is slower and more passes, in different directions, are required to sweep up the pods. Thus the best results will be obtained when medic has actually been sown on prepared nursery plots, so that the sweeper can straddle this row and brush up the pods when they are mature.
For best results from the sweeper, these plots should be rolled early in the season to make them even. Rolling after planting is primarily of interest in order to ease mechanization of harvest, particularly if the crop is short or has lodged. But it can also improve germination by improving contact of soil and seed, helping the seed to germinate and the roots rapidly penetrate, and fix themselves in the earth. So ICARDA has developed a low-cost roller for this purpose. Again, it was built in prototype form by ICARDA and bulk production is done by Faraj Allah Edlebi. It is intended for use in preparing for harvest mechanization of vetch, as well as medic.
Rolling will give its best results if the soil is neither too wet nor too dry; wet conditions cause soil to stick to the roller, and dry soils cause soil accumulation in front of the roller, an action which is more like plowing than rolling. This 'plowing' can be solved by adjusting the drawbar connection to the tractor; raising the drawbar slightly will permit the wheels to roll instead of plow.
Rolling may be done as soon as possible after planting, but it must be restricted to periods when the soil is sufficiently dry. The rolling operation should stop when the crop height is approximately 10 cm, or when it could cause damage to the plants. The roller can be towed for short distances, having wheels which can be raised out of harm's way when the machine is in use. This makes it possible for several farmers in a given area to use the same roller.
The thresher, like the sweeper, was designed specifically for medics.
The pods do not always have to be threshed. Farmers in dry areas with 200 to 300 mm annual rainfall can sow pods directly, thus minimizing the risk of losing all the seed if a drought occurs during pasture establishment. Using this method, if there is overgrazing in the first year and no seed is set, there will still be seed in the ground. Each medic pod, in fact, is nature's equivalent to the peat pots used in greenhouses to establish seedlings. They absorb water, provide insulation from the elements, and shelter the Rhizobium needed to inoculate the roots of the legume seedling, enabling it to
|
|
|
|
|
|
|
|
|
|
fix nitrogen from the atmosphere. In dry areas where the risk of establishment failure is higher, sowing pods may be better than sowing seeds.
Normally, however, the user who is rehabilitating degraded and marginal land will require as high a percentage of germination as possible. Moreover, in areas with more than 300 mm of annual rainfall, there are good reasons for sowing threshed seeds. In this case it is inefficient to sow pods because they may increase the risk of establishment failure. The germination percentage of the seed differs depending on the species, but in general annual medics have a high natural degree of hard-seededness. So it is useful in some circumstances to thresh the seed from the pods; this often scratches or scarifies them, allowing moisture to penetrate and germinate the seed. The Maktabi/ICARDA seed thresher is designed with this purpose in mind. In the process of removing the seed from the pods the seed coat is scratched, making a majority of the threshed seed germinable. It can rapidly thresh seed from a range of medic species, and yields more than 85% clean, unbroken seed.
Designed and built in collaboration with the Maktabi company of Aleppo, the thresher is moveable--it comes mounted on a chassis with three wheels and a pull bar, to facilitate transportation and maneuverability. It works on electricity, but for areas where electricity supply is often a problem, it can be changed to a petrol-driven operation.
Unthreshed pods are sieved to remove stones and straw prior to their going into a hopper that holds about 2 kg of material. The pods are metered into a threshing cavity with a removable threshing drum with six fixed rasp bars, and the chamber wall has two adjustable rasp bars. Pods are threshed by collision with fixed and rotating rasp bars. Adjustment of these bars on the drum wall allows passage of different seed sizes without breakage.
After threshing, the seeds drop to a shaking table with a first screen that permits separation of dust and fine material. On a second screen, seeds fall through to a tray while coarse material continues off the table into a rubbish bin. On their way to the tray the seeds fall down an inclined plane against which a stream of air is directed to remove additional fine material. Clean seed results. If the germination is above 90%, the amount of seed to be planted is 20-25 kg/hectare.
On average, the thresher can process 150 kg/day of pods or 50 kg/day of clean/scarified seed--enough to sow 2-3 hectares.
Up to now there has been no indigenous medic seed production in WANA, even
|
|
|
|
|
|
|
|
|
|
though the crop originated in the region. Seeds have been imported from Australia, but they are expensive and are not adapted to the local conditions as local seeds, especially in areas with cold winters. ICARDA could supply small quantities of appropriate local seed to get farmers started, but if this technology is to be transferred on a regional level, seed production must become a commercial operation, even if only as a cottage industry. Village-based pasture seed units will allow pasture seed production outside the formal seed industry channels. This process will require a good deal of publicity to make farmers aware of how to improve pasture feed resources at minimum cost. The huge area in need of revegetation throughout the region justifies the relaxation of purity controls in pasture seed production.
Now ICARDA is attempting to stimulate manufacture, distribution and use of these three machines so that such an industry could become a reality. Attention will also be paid to methods of preparing fields for harvest, demonstrating the machines with other forage species, cleaning the seed pods and storing seed.
ICARDA intends to build up a network of machines for pilot operation by national programs and a few key farmers, in the hope that the technology will spread.
It is affordable technology. The sweeper costs the equivalent of about US $300. The roller is about US $ 3500 and the thresher is about $US 5500, so these two, at least, may have to be shared between groups of farmers; but as they are easy to transport, this should not be a major problem.
In any case, ICARDA thinks that the most crucial challenge is picking the seed pods off the ground in the first place, and the sweeper is perhaps the most important link in the chain.
The machines are simple, but starting a farmer-controlled seed industry in WANA is revolutionary.
Imad Haidar is a consultant in the Natural Resources Management Program (NRMP) of ICARDA. Walid Bou Mughlebay works on Pasture and Forage Agronomy and Machinery in NRMP. Scott Christiansen was formerly engaged in research which included pasture species at ICARDA. He is now posted at ICARDA's Cairo office.
|
|
|
|
|
