Conservation agriculture Tanzania_casestudy.pdf - Sokoine ...

herbicide was completely abandoned due to its residue effects in the soil and thelack of money to buy it. During the trials, farmers mixed Round-Up with Atrazine,which reduced growth on legume crops. Farmers in Kikatiti normally intercropmaize with beans or pigeon pea. Monsanto, after failing to convince farmers to usetheir herbicides, moved out of the area.5 Conservation agriculture practicesIntroducing conservation agricultureConservation agriculture is based on three major principles:1. Minimal soil disturbance with reduced tillage, zero tillage and directplanting2. Permanent soil cover, with the crop itself, cover crops, residues andmulch, to protect the soil from sun, rain, and wind and to feed soilorganisms3. Crop rotations through crop sequences, intercropping, relay croppingor mixed crops to avoid diseases and pestsLabour shortage and low yieldsFarmers are interested in any technology that will increase yield at an affordable costand save labour. The elderly complained of drudgery, especially during weeding inconventional practice. Manual weeding is labour intensive. By the time a farmeris through with weeding the entire farm, the part weeded first will usually showsigns of new weeds and weeding has to be repeated. Therefore, families will weedonly where they can and the remaining part will be done if they can afford hiredlabour. Similarly, preparing land is very labour intensive, engaging whole familiesand renting draught animals for those who do not own cattle. This leads to lowyields from poor timing, late planting and inefficient rainwater use.Soil fertility and degradationSteiner (2002a,b) reported that soil organic matter decomposes more rapidly in thetropics because of the higher temperatures; soil inversion increases soil aeration andaccelerates decomposition. During the focus group discussions, farmers concurredwith Steiner: the main aim of soil inversion is to bury crop residue, thus producingoptimal conditions to germinate seeds, increase water infiltration and eliminateweeds. However, with time, such practices exhaust soil organic matter. Steiner alsonoted that losing soil organic matter deteriorates soil structure, crusts and seals thesoil surface. SCAPA and RELMA identified soil hardpan, soil nutrient depletion,and low soil moisture content as a result of poor retention and failure of rainwaterto infiltrate as the main yield constraints (RELMA 2002). As a result cover cropswere introduced, mainly through SARI, to provide soil cover to replace the cropresidue already depleted from grazing.22 Maguzu et al.