Conservation agriculture Tanzania_casestudy.pdf - Sokoine ...

History of conservation agriculture in KaratuIn the latter part of the 1990s, subsoiling (ripping) was introduced in two districts:Karatu and Babati (Bishop-Sambrook et al. 2004). Key facilitators of conservationagriculture in Karatu include KDA, SARI and TFSC. In 1997, a soil conservationproject began in Qurus village. The aim of the project was to encourage theadoption of cover crops such as mucuna, lablab and sunn hemp (Crotalaria spp.)through village demonstrations coordinated by KDA. In 1998/99 mucunaperformed well during the first year of the project, but it was not adopted. It lackedmarketing opportunities as it was a new product without established marketingchannels. Furthermore, prolonged drought led to poor germination of seeds andpoor establishment of cover crops.In 1998/2000, SARI and TFSC conducted joint subsoiling activities and covercrop improvement by introducing lablab, which fetches a ready market and isedible. Development of conservation agriculture under SARI and TFSC wasin three phases. Phase 1 included subsoiling with tractor (1998) and involved 28free demonstration plots sponsored by GTZ and implemented by TFSC. Thedemonstration aimed at motivating farmers to adopt heavy tillage using the chiselplough in the first year, essentially to break up the hardpan and decompact the soil.Phase 2 introduced cover crops in 1999/2000 in 14 trial sites of subsoiled plots.Phase 3 used no-till and direct planting equipment such as jab planters, draughtanimalpower knife-rollers, no-till planters and sprayers, and tractor-mounteddirect-seed drills introduced in 2002.It was realized that to some extent pigeon pea, which is commonly intercroppedwith maize, could be used as a cover crop. For many years, farmers had observedthe positive impact of pigeon pea on soil fertility, the crop’s ability to break hardpan,and its positive impact on moisture retention and weed control, particularly ofnoxious weeds such as Digitaria spp.7 Conservation agriculture practicesConservation agriculture aims to conserve natural resources and to make moreefficient use of them through integrated management of available soil, waterand biological resources. The principles guiding the application of conservationagriculture are:• Reduce or minimize soil disturbance (that is, soil disturbance in cropproduction is restricted to the absolute minimum).• Maintain soil cover of live or dead vegetal matter on the soil surface. Thisimplies that crop residue should not be burned or removed from the fields.• Rotate crops over several seasons. In addition to minimizing the build up ofdiseases or pests, crop rotation is essential in sustainable farming as it allowsdifferential use of the soil over time, thereby optimizing plant nutrient usethrough synergy between different crop types. Alternating shallow-rootingcrops with deep-rooting ones is also an important feature in deciding cropsin a rotation.78 Ringo et al.