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Wageningen University (2014)

Exploring the potential of soil and water conservation as an adaptation strategy to climate change

Lutz, F.

Titre : Exploring the potential of soil and water conservation as an adaptation strategy to climate change

Auteur  : Lutz, F.

Université de soutenance  : Wageningen University

Grade  : Master of Science (MS) 2014

Résumé
Developing countries which rely on agricultural production for survival are vulnerable to the negative impacts of climate change. An increase in droughts, floods and other extreme events in Africa are likely to have an impact on agricultural production and food security. The Research Program on Climate Change, Agriculture and Food Security (CCAFS), explores for methods to overcome the threats to agriculture and food security in a changing climate by searching for possibilities to help the vulnerable communities to adapt to climate change(CGIAR 2014). This is done by for instance, promoting adaptation strategies towards climate change. Soil and water conservation (SWC) are examples of such strategies. SWC aim to alleviate growing water shortages, worsening soil conditions, droughts and desertification. These strategies are generally low-cost interventions, however, they can be still too risky for very low-income households. The positive effects of SWC strategies can often only be observed after a long time of managing. In this study, the effect of SWC as an adaptation strategy to climate change has been studied in one of the CCAFS study sites in Kenya. The study area was located in Makueni. In this area farmers have been managing under SWC strategies for a long time. This opened opportunities to study the long-term effects of SWC strategies on soil conditions. Fieldwork is done in order to find if the SWC strategies have an effect on soil conditions, by studying the soil properties. A crop-growth simulation model is used to find if these possible effects on soil conditions result in higher water-limited yields for maize under current climate conditions. The use of a cropgrowth simulation model opened opportunities to study if SWC strategies can be used as an adaptation strategy towards climate change, by simulation different climate scenarios. The results of this study can confirm if the SWC strategies as promoted by CCAFS can indeed contribute as an adaptation towards climate change. The main SWC strategies in this area are applying terraces and intercropping. The fields where SWC strategies were applied, were paired up with fields were no SWC strategies were applied. These paired fields were sampled and analysed on different soil properties. The soil properties that were analysed in order to study the effects of SWC were nitrate, pH and soil moisture. The results of the analysis for the soil properties of the paired fields were used to study whether the SWC strategies had an effect on the current water-limited maize yields, under dry, wet and average climate conditions. If the strategies had an effect on the simulation of future maize yields was studied by using four different climate scenarios for 2050. This is done by using the crop-growth simulation model WOFOST. This model uses soil data, weather data en crop characteristics as input to estimate the yields per growing season. Higher contents of nitrate levels were found in the soils for the intercropping fields. The soil moisture was higher on the terraced fields. Terracing also resulted in an increase of waterlimited yields in a dry year. It also resulted in higher water-limited yields under different climate scenarios. This implies that terracing is not only a great potential as adaptation strategy for climate change but also increases yields under current climate conditions. Although higher nitrate levels were found in the intercropping fields, did this not result in an increase of waterlimited yields. For both current climate conditions as well as future climate scenarios, yields did not increase by intercropping. Applying SWC strategies as promoted by CCAFS indeed improves soil conditions and terracing contributes as an adaptation towards climate change. Therefore continuing with stimulating farmers to apply such strategies –as done by CCAFS- can decrease threats to agriculture and food security in a changing climate. Increased water-limited yields by applying terraces makes farmers less vulnerable towards climate change and more food secure. Applying intercropping as SWC strategy likely has positive effects as well. However, the nutrient-limited yields should be evaluated in order to confirm this.

Mots clés : soil conservation / water conservation / climatic change / climate adaptation / agricultural production / food security / soil properties / yields / kenya

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Page publiée le 13 février 2015, mise à jour le 16 octobre 2018