5 years ago

Die Wirksamkeit von Boden

Die Wirksamkeit von Boden

Overall summary and

Overall summary and conclusions and productivity, restoring vegetation cover and ecological health, and in mitigating anthropogenic land degradation. This study show terracing and exclosure played a paramount role in reducing land degradation and/or restoring degraded lands. However, the interventions need improvement to maximize the benefit and balance peoples current and future needs. The main conclusions and recommendations are: i. The LULC and NDVI analysis showed restoration in areas where exclosure was implemented. The exclosure helped to improve vegetation cover and soil fertility. ii. Even if the population growth at the time of the study was at a slower rate than in previous censuses, it was still high as far as sustainable resources management is concerned, and agricultural lands have been increasingly fragmented. As a result, some farmers had a negative perception of exclosure as in their opinion it competed with grazing lands. Therefore, it is important to complement the natural resources conservation effort by family planning, implementation of non-agricultural economic options and use of alternative household energy sources beyond biomass. iii. The impact of exclosure on vegetation and soil fertility restoration was immense, and the mechanical SWC measures had complemantary effects. The mechanical measures enhanced in-situ conservation and soil fertility restoration. Unlike in other studies, no soil fertility restoration gradient was observed across the terrain, which is a positive impact. Hence, it could be a wise approach to compliment exclosure with mechanical SWC structures in order to achieve a quick and efficient impact. iv. On the other hand, the soil fertility restoration due to exclosure was nonlinear with agro-ecological zones, where higher restoration was observed in the Weyna-Dega (mild) than in the Dega (cool) zone. This could be attributed to the effect of climate (agro-ecological zone) on biomass production, vegetation types, and organic matter decomposition, which indicates the importance of considering the agro-ecological zone during exclosure planning. v. In general, terracing had a number of advantages with respect to reducing soil and nutrient loss through erosion. However, terracing alone does not improve soil fertility, as fertility loss is not only through erosion. Furthermore, terracing cannot fully halt erosion. In order to improve soil fertility, terracing should be supplemented by appropriate organic and inorganic fertilizer application based on the site-specific soil fertility level. 136

Overall summary and conclusions vi. The regular terrace maintenance and sedimentation helped terraces to develop to bench terraces, which in turn reduced topsoil fertility gradients within a terrace. It was found that terracing was found more effective up to 15% slope terrain. vii. The impact of terracing on crop production was in line with that on soil fertility. Like topsoil fertility, the crop yield did not show significant changes with terrace age, while nutrient removal through harvest continued, fallowing was reduced and there were no improvements in fertilizer use. This indicates that terracing at least helped to maintain topsoil fertility and thereby crop production, but terracing alone cannot significantly increase crop yields. viii. Yield gradients within a terrace were observed. Therefore, to reduce the gradients, it is advisable to use site-specific soil fertility amendment levels. ix. In some crops, terracing induced negative impacts at the lower terrain positions. This effect could be reduced through selecting appropriate crops in this position, particularly by excluding crops sensitive to water-logging and regularly drain accumulated water. x. By and large, the current analysis clearly showed that SWC practices in general and farmland terracing and exclosure in particular played important role to halt land degradation and to restore degraded lands. 9.3 Research and policy implications Land degradation is caused by various factors and has wide impacts. As a result, restoration measures aimed at restoring environmental and ecological health, which involves various factors. The factors could influence each other, where the results have interlinked outcomes. Thus, land degradation assessments need to use an interdisciplinary approach and broad data sets. The current study involved biophysical resource assessments using soil and crop yield data, and also temporal satellite data. It examined changes in soil fertility and crop production on farmlands due to terracing and also analyzed LULC and NDVI changes and soil fertility conditions due to exclosure. However, the subsequent follow-up studies are required to fully understand the processes, which could give information on how to maximize the restoration and outcomes of the conservation practices. 137

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