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Zero-tillage seeders

The most obvious practical obstacle to the uptake of conservation agriculture (CA) by large numbers of farmers in Central and Western Asia and North Africa was that zero-tillage (ZT) seeders—planters or seed drills—were not commercially available.

In addition to creating excessive soil disturbance, conventional seeders are ineffective in undisturbed soil especially if large amounts of crop residues are present. Initially, the uncultivated soil is much harder than tilled soil, and the springs and tines on conventional seeders are unable to sow the seed and fertilizer at a consistent depth. Also the power of tractor required to pull the seeder is increased. But more importantly, conventional seeders are highly prone to the build-up of crop residues and mud on the tines, causing blockages and ineffective distribution of seed.

Imported ZT seeders are too complex, too big, and too expensive for resource-poor small landholders. They typically cost between US$20,000 and US$60,000—far beyond the reach of smallholders—and need to be maintained by specialist workshops, and pulled by large, powerful tractors.

Working with rural communities, ICARDA and its partners have shown that it is possible to make and repair simple, effective, and low-cost CA seed drills using local expertise and materials in places like Syria and Iraq. An Australian–ICARDA project in Iraq and Syria worked with local workshops to adapt seed drills already used by smallholders in those countries for use in CA—planting seed directly into untilled soil with crop residues. The Syrian manufacturers were more advanced and had access to better materials than those in Iraq, and consequently made more rapid progress.

The main changes to make conventional seeders suitable for ZT can be summarized as follows:

  • Narrow “knife” points replaced the typical “duck-foot” points to reduce soil disturbance and drag by cutting a narrow slot in the undisturbed soil.
  • Tines with stronger springs and an adequate break-out force were fitted to enable seeding into hard, undisturbed stony and shallow soils without risk of damage to the seeder.
  • Row spacing was increased to 20–25 cm to allow reasonable flow of residues.
  • The seeder frame was raised and longer tine shanks fitted to avoid residue clumping when sowing into thick and standing crop residue.
  • The distance between each row of tines on the seeder (rank) was increased from 25 to 50–60 cm to improve residue flow, and tines were placed on 3 or 4 ranks in the 4-meter-wide seeder models.
  • The seed/fertilizer box height was raised to provide good flow of seed and fertilizer down the pipes into the soil, especially for seeders with widely spaced tine ranks. Many seeders were also fitted with two separate boxes, one for seed and the other for fertilizer, to allow greater flexibility in application rates and placement.

The locally made Syrian seeders cost US$2,000 to US$6,000—a fraction of the cost imported machines. And in field trials, the locally-made seeders worked as well as the imports; this was later confirmed by farmer experience. At US$2,000, a locally produced ZT seeder could pay for itself in one year if used to plant only 10 hectares of wheat in Syria, and about 7 hectares in Iraq.

In 2013, 121 Syrian seeders had been manufactured and were being used by farmers within the country. In addition over 50 seeders were sold to Iraq, Jordan, Lebanon, Tunisia, Algeria, and Morocco. In Iraq, over 20 seeders have been converted to ZT and number of imported ZT seeders are also being used. The first prototype ZT seeder was manufactured in late 2012, and others are planned.