Conservation agriculture Tanzania_casestudy.pdf - Sokoine ...

than being carried home for animal feed. However, this does not provide much soilcover because of free grazing.Cover crops, particularly mucuna, lablab and pigeon pea, are managed by slashingthem after harvest then leaving them to sprout and provide soil cover for anothercrop, usually maize. In some cases, the cover crop is left to wilt after harvesting thebeans.Crop rotationMost small-scale farmers have not achieved formal crop rotation. The main reasonsare shortage of land and the traditional practice that a farm can never be left fallowfor a season without planting maize, the staple food in most areas. The area undermaize cannot be reduced. The only rotating is to intercrop other crops with maize.This maximizes the use of the field, which may yield more than one crop.Conservation agriculture intercropping and crop relaying are mainly with maizeand legumes. Maize is intercropped with lablab, pigeon pea, soybean and beans.Crop rotation is minimal and is mainly practised in intercropped farms with pigeonpea and maize, followed by pigeon pea alone, followed by maize and beans orlablab. Vegetable farmers often plant maize and beans, then vegetables, then maizeand beans. Rotating crops can restore soil fertility and increase soil organic matter,depending on the crops used.Indigenous knowledgeIndigenous knowledge has been practised by farmers before conservation agricultureprojects. In coffee plantations, farmers practise no-till technology with minimal soilinversion during the initial planting. Weeding is done by scraping the soil. Theleaves that fall and are pruned are spread on the soil. Since coffee is a perennialcrop, this is beneficial to the soil. Minimal herbicide is applied.Agroforestry and contour construction is traditionally widely used, especially nearMt Meru. They have been practised since colonial times and integrate well withconservation agriculture in conserving water and soil. Trees are mainly grown toprovide shade, prevent wind erosion, provide fruit and fodder and mark territory.The unique coffee, banana, maize, beans and tree agroforestry system has survivedfor the past 200 years. Coffee and banana are planted under trees grown for timber,fruits, medicine, animal fodder and shade. The system provides continuous groundcover and a high nutrient cycling (Kaihura et al. 2001).Other indigenous practices include intercropping pigeon pea, soybean, sweetpotatoand pumpkin, which act as cover crops after the main crop is harvested. Theyprovide a good canopy if densely planted. But pumpkin usually covers only smallparts of a field during its growing stage. Pigeon pea provides biological chiselling. Itstough tap root breaks hardpan and may be cheaper and more sustainable, thoughslower, than ripping or subsoiling, since the root channels remain in the soil (FAO2002). Pigeon pea may help to prevent compaction of subsoiled plots.Arumeru District 25