Flower Power: flower-strips host bees & sequester carbon in soils

Flower-strips are increasingly recognized as mandatory elements in agricultural landscapes for pollinators to survive. In this study, we raised the hypothesis that flower-strip traits additionally affect biogeochemical cycling towards climate change mitigation. Therefore, we investigated soil carbon and nutrients stocks in paired comparison to adjacent land use and looked at water retention.

Two study farms of 50 ha in southern Germany were sampled once in spring, summer and autumn. The examined flower-strips of both farms were sown in 2011 and are in use since then. Pairwise sampling reduces the influence of the expected high variation in soil parameters. For each pair we sampled 3 depths: topsoil (0-5 cm), plow horizon (20-25 cm) and subsoil (30-35 cm). Different parameters of soil carbon, nitrogen, nutrients and water will be presented with a focus on clay bonded carbon.

Preliminary results indicate that flower-strips significantly increased nitrogen availability, soil carbon stocks and accordingly showed a trend to improve the water storage capacity in the plow horizon. We did not observe a statistically significant effect on nutrient availability.

Provided that these results will be confirmed, flower-strips traits could go beyond the important trait of giving pollinators a home in vast agricultural landscapes. By slightly increasing the amount of flower-strips in these landscapes, a significant increase in carbon sequestration and water retention will be achievable adding to the 4 per mille goal of the UN.