S13 - Session O5 - Reduced fertilizer use – increased risk? – Qualitative and quantitative analysis of economic risks and risk perceptions of German vegetable growers

Authors: Hildegard Garming *, Linda Kristina Bork, Hanna Wildenhues, Henriette Burger

Vegetable production is a risky business. The compliance with ever increasing quality standards is condition to access markets, which are dominated by few retailers, in Germany as well as other European countries. Achieving these quality standards in open field vegetable production is difficult, since weather conditions and infestation with pathogens cannot fully be controlled by producers. The increasingly restrictive legislation on fertilizer use, targeting nutrient losses and pollution of water reserves, is often perceived as a burden, limiting their options for crop management and increasing quality risks, since vegetables are particularly susceptible to quality defects from nutrient deficiency. During a five-year project in three major vegetable-growing regions in Germany, different measures to increase nitrogen (N) efficiency and thus reduce fertilizer use, were implemented as on-farm experiments and evaluated with respect to yields, quality, costs of implementation, soil N-contents and practical feasibility. This paper presents results of an assessment of the risks associated to reduced N-fertilization, which was conducted in the last project year. A qualitative assessment of farmers' perceptions of risks related to N-fertilization and the increasingly restrictive regulation is based on interviews with project participants. Their project experiences, data from the on-farm trials and additional secondary data from literature and economic data bases were then used to model vegetable production systems with different levels of fertilizer use and measures to mitigate nutrient losses. Considering uncertainty of yields and prices, Monte-Carlo simulation was used to determine the distribution of gross margins in the different evaluated scenarios. The illustration of economic risks in figures and graphs as outcome of the simulations, and the possibility of demonstrating the impact of small modifications of assumptions on the results proved to be a helpful tool for communicating the results of complex risk analyses to farm advisors and vegetable growers.