Diversified Farming Systems – An evaluation of ecological benefits, economic costs & risks farmers face

Abstract

Biodiversity and associated ecosystem services in cultural landscapes are declining due to increasing agricultural production. Human population growth and changing consumption patterns cause higher demands on agricultural products and accelerates the intensification of agricultural practices. Intensification of agricultural management is a major reason of ecological problems such as homogeneity of landscapes, rising greenhouse gas emissions, eutrophication, loss of soil fertility and productivity. These negative externalities of intensive agricultural production result in high loss of biodiversity and associated ecosystem services, such as the loss of species, pollination, and biological pest control as well as reduced carbon sequestration, enhanced nutrient leaching and higher soil erosion. To mitigate these ecological problems, a new model called “Diversified farming system” has been proposed. Diversified farming systems include a range of agricultural management practices that promote ecosystem functioning and related ecosystem services at different spatial and temporal scales and contribute to the promotion of critical ecosystem services. Further diversified farming practices may replace agricultural production inputs such as fertilizer or chemical plant protection measures, which is economically advantageous. This thesis focuses on a better understanding of the ecological and economic consequences of diversified farming systems. The ecological-economic expectations of farmers regarding benefits and costs of diversified farming practices were analyzed, including the discrepancy between scientific evidence and farmers’ arguments for low adoption of diversified farming practices. The thesis ends with recommendations on how and which political incentives may lead to higher implementation rates of diversified farming practices. For such purpose, the thesis is divided into four chapters: A first introductory chapter gives a general overview, summarizing and discussing current scientific knowledge and research gaps of diversified farming systems. Furthermore, the first chapter gives an outline of the thesis. In the second chapter, we systematically reviewed and synthesized scientific evidence of the ecological and economic performance of diversified farming practices. We found that diversified farming practices provide substantially greater biodiversity and associated ecosystem services than non-diversified systems. The ecological benefits for the farmer were partly insufficient to outbalance economic costs in the short term, even though many examples showed that diversified farming practices can lead to higher and more stable yields, increase profitability, and reduce risks in the long-term. In the third and fourth chapter of this thesis, we present results from face-to-face interviews of farmers on the perception of ecological-economic performance and risk change by potential implementations of diversified farming practices in Germany. The results of the third chapter show that gross margin increased for diversified crop rotation, while reduced tillage and direct seeding resulted in lower gross margin, because of expected yield reduction and higher variable costs. High soil quality leads to higher gross margin expected. The fourth chapter expands on the perception of risk change by implementation of diversified farming practices. We found that farmers expected a risk reduction by cover crops and diversified crop rotation, due to the portfolio effect, but a risk increase by reduced tillage and direct seeding, due to greater weed pressure. Large farm sizes and less fertile soils are related to the perception of reduced yield risk, presumably because of additional opportunities to increase profits through the implementation of diversification. In conclusion, diversified farming systems can substantially contribute to maintain biodiversity and to support the provision of ecosystem services. In order to increase the implementation rate of diversified farming practices, incentives are needed to reward for ecological benefits on the farm level. However, consideration of farm features and farmers’ experience and expectations may help to adjust incentives by agri-environmental policies.