Wolfgang Zech

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Soil fertility and leaching losses of nutrients were compared between a Fimic Anthrosol and a Xanthic Ferralsol from Central Amazônia. The Anthrosol was a relict soil from pre-Columbian settlements with high organic C containing large proportions of black carbon. It was further tested whether charcoal additions among other organic and inorganic applications(More)
Many soils of the lowland humid tropics are thought to be too infertile to support sustainable agriculture. However, there is strong evidence that permanent or semi-permanent agriculture can itself create sustainably fertile soils known as 'Terra Preta' soils. These soils not only contain higher concentrations of nutrients such as nitrogen, phosphorus,(More)
Application of organic fertilizers and charcoal increase nutrient stocks in the rooting zone of crops, reduce nutrient leaching and thus improve crop production on acid and highly weathered tropical soils. In a field trial near Manaus (Brazil) 15 different amendment combinations based on equal amounts of carbon (C) applied through chicken manure (CM),(More)
This paper discusses the effects of intercropping and tree pruning on root distribution and soil water depletion in an alley cropping system with Acacia saligna and Sorghum bicolor in northern Kenya. Root distribution was determined by destructive sampling, and the soil water suction was measured with tensiometers and gypsum blocks, both up to 150 cm depth.(More)
Leaching losses of N are a major limitation of crop production on permeable soils and under heavy rainfalls as in the humid tropics. We established a field trial in the central Amazon (near Manaus, Brazil) in order to study the influence of charcoal and compost on the retention of N. Fifteen months after organic-matter admixing (0–0.1 m soil depth), we(More)
In the semi-arid part of northern Tanzania, the native tropical woodland is undergoing a rapid conversion into agricultural land. This has resulted in drastic ecological changes in the region. This study was undertaken to investigate the effects of these changes in land use systems on the amount and composition of SOM in bulk soil samples and size(More)
Frequent charcoal ®ndings together with black carbon concentrations in the soil organic matter (SOM) of up to 35% provided evidence that black carbon is important for the SOM stability in Terra Preta soils. This paper aims to investigate whether black carbon is additionally stabilised by organo-mineral complexation. For this purpose black carbon was(More)
requires analytical methods that can (i) accurately monitor changes in the amount, nature, and dynamics of We used natural 13C abundance coupled with particle-size fractionSOM pools in natural and human-influenced systems ation to evaluate soil organic carbon (SOC) dynamics following deforand (ii) estimate C fluxes between the soils and atmoestation and(More)
Rapid turnover of organic matter leads to a low efficiency of organic fertilizers applied to increase and sequester C in soils of the humid tropics. Charcoal was reported to be responsible for high soil organic matter contents and soil fertility of anthropogenic soils (Terra Preta) found in central Amazonia. Therefore, we reviewed the available information(More)
Tree root systems may improve soil fertility through carbon inputs, uptake of leachable nutrients and maintenance of soil biomass, but can at the same time reduce crop yields by competition for water and nutrients. Quantitative information about the positive and negative effects of tree roots and their changes in space and time are necessary for the(More)