Conservation agriculture Tanzania_casestudy.pdf - Sokoine ...

The direct seeder was second, and rope and hand hoe in ploughed plots was last.The ripper, direct seeder and jab planter had good germination. The ripper waseasiest to use. The direct seeder cost the most, but used the least labour. However,there was inadequate soil cover at planting, which favoured the jab planter over theripper. Farmers who owned oxen considered the jab planter a step backward. Poorfarmers without work animals liked the jab planter.Dry seeding and labour peaksIntroduced conservation agriculture technology greatly improved the timelinessof planting and weeding in the area. Before conservation agriculture, plantingfollowed ploughing, which began with the rains at the end of November and earlyDecember. It takes about 32 person-hours per hectare to plant seeds and placefertilizer. The ripper moved up planting from early December to November, beforethe rains. Idle time became productive and at the same time, the peak demand forlabour, for planting and weeding, is spread evenly. The rains come when the seedsare already in the soil. The ripper, which opens furrows without full cultivation, canget the whole farm planted before the rains and has good seed germination.However, dry planting carries risks. A light first rain, although it will not fullygerminate seeds will cause them to swell and rot, requiring replanting. Care isneeded to separate seeds from basal fertilizers, if they contain nitrogen or improperlydecomposed manure, yet not so far apart to hinder fertilizer use by roots. Contactof the two will scorch the seeds and they will germinate poorly.Soil coverIn the trial plots cover crops were sown in the maize after the first weeding. Maizeresidue provided soil cover. Individual farmers could choose a cover crop out ofDolichos lablab, mucuna, canavalia, Crotalaria orchroleuca, Lupinus albus (white lupin)and Vicia vilosa (hairy-pod vetch). White lupin and hairy-pod vetch were for thehigh-altitude Kisilo site (2100 m). Following the maize and cover crop seed harvest,the vegetation had to be protected from free-range livestock, seekers of cut-andcarryfeed for their livestock, and bush fires. Lablab, mucuna and vetch are verygood livestock feeds. Fences have been effective in Kisilo village, but not in Msheweand Wanging’ombe.Awareness campaigns on the detrimental effect of bush fires and the benefits ofsoil cover have started to bear fruit in some villages, such as Mayale. No livestockhave been allowed to graze on a 5-ha farmer field school plot for three years, inspite of the absence of fences. Bush fires have been curbed in a similar way. Villagebylaws that restrict bush fires and call for compensation or fines for crop damageare normally enforced. Interpretation of the bylaws is yet to be extended to defineresidues or soil cover as a ‘crop’. The bigger challenge is enforcing the bylaws whencattle herds are in transit and on the run.No external mulches were brought in from outside the field. Inedible cover crops,such as Canavalia ensiformis, have proved valuable during the dry season, especiallyin the drier Wanging’ombe Division. Live hedges of Tephrosia vogelii were preferredin Mshewe, but the shrubs failed to survive in Wanging’ombe.124 Mkomwa et al.