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A long-term experiment comparing no-till with conventional tillage systems across ®ve rotations was evaluated 11 years after initiation. The objectives of the present paper are (1) to report differences in soil chemical properties (namely soil organic matter, total nitrogen, phosphorus, potassium and pH) that have resulted by converting from conventional to no-till under contrasting cropping systems and (2) to draw tentative conclusions and recommendations on fertility status and fertilizer use and management. Soil in the no-till system had increased surface soil organic C levels relative to conventional tillage regardless of rotation. In addition, depending on the rotation, the N and P content of the soil improved with no-till compared with conventional tillage. In other words, no-till has helped to retain soil organic matter (SOM), conserved more N, and resulted in increased extractable P and exchangeable K concentrations in the upper root-zone. Hence, wheat produced in a no-till system may receive more nutrients from decomposition of SOM and acidi®cation of the seed zone. It is possible that lesser amounts of fertilizer nutrients will be needed because of the greater ef®ciency of nutrient cycling in no-till systems relative to conventional systems.

Abstract-

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The minerals in the tailings, subject to the action of water and atmospheric oxygen, can generate Acid Mine Drainage (AMD). The latter is considered the most important environmental issue facing the mining industry. Its environmental impacts include the destruction of the flora and fauna in infected rivers and contamination of groundwater. The abandoned mine site Kettara, located about 32 km northwest of Marrakech (Morocco), chosen as a pilot site for this study, more than 3 million tons of tailings stored at ground level without any concern for their environmental consequences. These solid residues, with high concentrations of heavy metals (As, Pb, Fe, Cu ...), produce leachate very acidic (pH <2.9) may contaminate the water resources of the region. To mitigate the DMA phenomenon in this mining site, different protocols have been proposed using candy sludge (Mud Pulp Sweets: MPS), rich in carbonates from the Moroccan Sugar Company Unit (COSUMAR) and red clays (Clays: CLY) of the city of Safi. Physicochemical characterization and mineralogical of these two materials was performed an provided promising results regarding the effectiveness of the use of alkaline materials in the stabilization of tailings Kettara. European Scientific Journal May 2016 edition vol.12, No.15 ISSN: 1857 -7881 (Print) e -ISSN 1857 322 Indeed, these starting materials are provided with a net neutralizing power which is of the order of 878.5 kg CaCO3 / t for MPS and 299 kg CaCO3 / t for CLY. The valuation of MPS and CLY, as a main component of an alkaline amendment, is likely to significantly reduce the effects of DMA in this semiarid climate mine.