Ecosystem services of arable land in response to cropping systems and drought.

Agroecosystems are nowadays often confronted with ecosystem degradation due tounsustainable intensification and climate change. One reason for intensification is that theprojected demand for food and feed is increasing due to global population growth and dietarychanges. Additionally, drought events, which are projected to increase in both frequency andseverity in the future, will potentially have strong effects on the ecosystem services providedby agroecosystems. Organic farming has been proposed to better cope with current agricultural challenges inclimate change and increasing needs for food. However, whether organic farming can solvethe trade-off between production and non-production services even under droughtconditions remains unclear. Likewise, conservation tillage might provide considerableecological benefits compared to conventional tillage, but the contribution of differenttillage methods to the resilience of agroecosystems towards drought needs furtherinvestigation. The objective of this study is to assess the response of ecosystems services in organicand conventional cropping systems with conventional and conservation tillage tosimulated drought. Several provisioning, supporting and regulating ecosystem servicesare being measured. We collect data on provisioning, supporting and regulatingservices. First results of treatment effects on litter decomposition, a supporting ecosystems servicethat was assessed via the Tea Bag method, will be shown. The method involvestwo types of Lipton tea with different C:N ratios: Rooibos tea, characterized bya slow decomposition rate (wide C:N); and green tea, characterized by a fasterdecomposition rate (narrow C:N). The experiment was conducted in a pea and barleymixture and a maize field to test for the effects of drought and cropping systems onlitter decomposition rate. Tea bags were installed in the uppermost 5 cm of thetopsoil. Decomposition was assessed during three periods: 1) Tdrought: duringthe drought treatment; 2) Tpostdrought: during the post-drought (recovery) phase(after drought until harvest); 3) Ttotal: during both drought and recovery phases.The results show that except for the wide C:N litter during the post-drought phaseonly, drought decreased decomposition. The type of tillage affected decompositionduring the post-drought phase only. Significant differences between organic farmingand conventional farming were only found in Ttotal with higher decompositionrate under organic farming. Generally, drought affected decomposition similarlyin both crops and for both types of litter. This indicated that in the future morefrequent phases of drought will significantly impact on nutrient cycling in arablesystems. [ABSTRACT FROM AUTHOR]