The report covers the results of intensive data collection across five years, and three headwater catchments totalling around 3,000 hectares. We weren’t surprised by the large turnout to the launch. This is a project with exceptional experimental rigour, practical grounding and multiple objectives that are highly relevant to current policy for water management in agricultural catchments. The most notable results are worth summarising here.
Phosphorus concentrations at the base of the two ‘treatment’ catchments and one control catchment have increased during the five-year period. Although high phosphorus concentrations are often associated with high sediment concentrations during peak winter stream flow, for most of the time, during base flow, high phosphorus concentrations are the result of discharges from sewage treatment works. The increase may be influenced by the relatively low concentrations associated with high summer flows during 2012, but the fact remains that domestic sources of phosphorus are a major issue in rural catchments. Both agricultural and domestic sources are difficult and slow to address but our research is improving our understanding of the issues.
Landscape scale aquatic biodiversity, as represented by aquatic and wetland plants, has increased in the two ‘treatment’ catchments in response to the creation of new wetland habitats, while remaining constant in the control catchment where there has been no such management. This is the first unequivocal demonstration of this process and is extremely encouraging in terms of the potential for landscape scale conservation of aquatic wildlife on farmland more widely.
Modelling of our data suggests that a switch from plough-based crop establishment to a no-till approach could result in an 11% decline in peak flow and associated downstream flooding. The same change in crop establishment strategy could also result in a 38% reduction in sediment load exported from the catchments under most rainfall conditions. This would also help to reduce flood risk because of reduced sedimentation of drainage channels in the lower catchment. We will be exploring to what extent such changes are feasible within the constraints currently expedrienced by farm businesses.
Our research continues. Take a look at the report for more detail, and I'll continue to post updates on this blog periodically.