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Weed species diversity may benefit from organic farming due to enhanced temporal diversification of crop species in a rotation and omission of herbicide applications. However, in intensively managed conventional systems, little evidence exists as to what extent diversified crop rotations contribute to higher weed species richness. Using an on-farm approach, the effect of crop rotation (organic, conventional diverse (CD) and conventional simple (CS) crop rotations) and weed control (with vs. without) on weed species richness, cover, community composition and crop biomass, was analysed in 24 winter wheat fields. Weed species with beneficial functions for invertebrates and birds were analysed separately. Weed species richness was higher in the organic crop rotation, but did not differ between CD and CS crop rotations. Weed control treatment reduced species richness in both conventional rotations, but not in the organic one. Redundancy analyses revealed that crop rotation intensity accounted for the largest part of the explained variation in weed species composition. Results from the study indicate that the maintenance of weed species richness and conservation of species with important ecological functions requires not only temporal diversification of crop species in the rotation, but also an adjustment of weed control strategies.

SUMMARYThe current rapid decline in biodiversity in human-dominated agricultural landscapes, both in Europe and worldwide, impacts on the provision of environmental services essential to human well-being. There is, therefore, a pressing need to develop and implement incentive-based conservation policies to counteract the ongoing loss of biodiversity. This paper presents results of a regionally-scaled conservation procurement auction, a type of incentive-based payments for environmental services (PES), targeted at the conservation of arable plant diversity. By matching arable fields that were participating in the PES scheme to control fields that were not enrolled in the PES scheme, two critical key characteristics were addressed, namely additionality and bid prices. Additionality was addressed by evaluating whether fields for which PES were issued had significantly higher arable plant diversity than the matched control fields. The cost-effectiveness of a conservation auction increases if payments compensate just farmers’ opportunity costs (in terms of forgone production); bid prices of participating farmers were thus also evaluated to determine whether they were related to their individual opportunity costs. The PES scheme proved to be highly effective in ensuring environmental services delivery through enhanced arable plant diversity on participating fields. In contrast, the potential of the proposed conservation auction design to raise cost-effectiveness has to be questioned, because bid prices submitted in this scheme substantially exceeded individual farmers’ opportunity costs. Therefore, bid prices were most likely influenced by socioeconomic factors other than opportunity costs. This case study illustrates potentials and pitfalls associated with the implementation of a PES scheme and, by evaluating the effectiveness of the scheme, contributes to an improved understanding of incentive-based mechanisms for both policymakers and practitioners involved in PES scheme design and implementation.

Background: The area used for bioenergy crops (annual row crops (e.g., wheat, maize), herbaceous perennial grasses, and short-rotation woody crops (e.g., poplar)) is increasing because the substitution of fossil fuels by bioenergy is promoted as an option to reduce greenhouse gas (GHG) emissions. However, biomass used for bioenergy production is not per se environmentally benign, since bioenergy crop production is associated with negative side effects such as GHG emissions from soil (dominated by N 2 O). N 2 O emissions vary greatly in space and time; thus, direct comparison of soil N 2 O fluxes from various agro-ecosystems is certainly crucial for the assessment of the GHG reduction potential from energy crops.

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Crop sequence patterns are considered as those schemes farmers apply within a single field to succeed crops over time, regardless of whether the same crop is grown continuously or a diverse rotation is used. This study aimed at identifying these patterns for a large and representative area in Northern Germany during a six-year period from 2005 to 2010. The analysis was carried out for the entire federal state of Niedersachsen (Lower Saxony) which has 1.8 million hectares of arable area.Field data was obtained by the Integrated Administration and Control System (IACS), which was developed for the administration of the European agricultural direct payments. So far, German IACS has not been exploited in the light of agronomical practice. In total, the available data comprised about 990 000 records for each year, each representing a single field out of the study region. Throughout the analysis, different agronomic and temporal scopes resulted in a different number of fields being accessible for evaluation. Ten major arable crops and crop groups were considered for the study; 184 701 fields representing 645 870 ha of arable area could be analyzed to identify crop sequence patterns over the six years. Thus, 16 836 combinations of the 10 major crops occurring in time and space could be described. Thereof, 12 crop sequence patterns were found covering 55.6% of arable area. For 2010, 619 447 fields representing 1 730 564 ha of arable area, were analyzed with regard to their respective crops and pre-crops. Maize, winter wheat, sugar beet, oilseed rape and potatoes were studied with special emphasis. On average, 46.9% of maize area were cropped following maize as a pre-crop. For winter wheat, self-sequences were identified on 30.0% of arable area. Oilseed rape and sugar beet are generally grown in typical rotations. However, 24.6% of arable crop area were considered as having a pre-crop which might be disadvantageous for crop health.Due to a rapid increase of maize area in the region, crop sequence patterns are undergoing a dramatic shift. It is concluded that a large proportion of arable area is potentially threatened by risks of pest and disease outbreaks as well as by economical over-reliance in a few cash crops. We demonstrate, that administrative data could offer many insights in agronomical trends and practices and should, therefore, be analyzed in more detail.

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