In 2006, the farmers of Rhotia village in the Karatu district of Tanzania made the switch from conventional tillage farming to conservation agriculture (CA). Similar to other smallholder farmers in Tanzania, these farmers suffered from low yields due to soil erosion, a common practice of grazing and removing all crop residues from their fields leaving them bare and vulnerable to the elements, and low use of organic or inorganic fertiliser.
In 2004, the Conservation Agriculture for Sustainable Agriculture and Rural Development (CA SARD) project began to teach the farmers of Rhotia CA, a sustainable way of growing crops and managing soil health. The first phase of the project from 2004-2006 used the farmer field school (FFS) approach as a means of teaching CA to 765 farmers in 31 groups across 3 districts (Arumeru, Karatu and Bukoba). The second phase, from 2007-2010, expanded to include another 4 districts, 86 FFS groups reaching more than 3,500 farmers.
To start, CA SARD provided training on CA to extension workers, who then facilitated FFS and trained the participating farmers in how to apply CA practices. CA SARD provided start-up assistance to the FFS in the form of field equipment, 10kg of maize seed, and 8kg of hyacinth bean seed and a 1-litre bottle of glyphosate herbicide. Each group tested several CA options depending on their priority problems using different combinations of tillage and multiple cropping of pigeon pea, hyacinth bean, beans or pumpkins.
The preferred option of the Mwangaza B FFS group was maize intercropped with hyacinth bean because it generated the highest maize yields (3.75 t/ha), conserved moisture, and controlled soil erosion. The second most preferred option was maize intercropped with pigeon pea which also produced high maize yields, controlled erosion, high levels of leaf droppings used for cover crops and improved soil fertility. Overall, yields under CA increased from 1.25 t/ha in 2004 to 7 t/ha by 2009. Labour requirements declined, and farmers also benefited from selling hyacinth bean and pigeon pea at a favourable rate of TSH 1,100 per kilogram (approximately US$1).
Although the introduction of CA produced significant benefits, these were met with many challenges. The use of crop residue for mulching directly competed with animal feed. With the adoption of CA, farmers stopped selling their crop residues to farmers with livestock and began to prohibit free grazing on their lands. Pastoralists who acquire 80% of their livestock feed from crop residue, especially during the dry season, suffered resulting in conflicts between the farming and pastoralist communities. Additionally, tractor and oxen providers lost significant business when farmers no longer tilled.