The Wensum Demonstration Test Catchment Project www.wensumalliance.org.uk/
Salle Farms Company has, over several years, been actively involved in Catchment Sensitive Farming and is currently participating in a UK wide project to improve water quality. Within the UK there are three Demonstration Test Catchments (DTC), funded jointly by DEFRA and the Environment Agency based on the River Wensum in Norfolk, the River Eden in Cumbria and the River Avon in Hampshire. The DTC projects are investigating the effectiveness of on-farm measures, to reduce diffuse pollution and thereby enhance the environment and biodiversity, whilst still maintaining sustainable food production. The initial phase has seen 24 hr monitoring of water quality to understand the sources of diffuse pollutants and the effect that mitigation activities have on farm economic performance.
The DTC project aims to evaluate the extent to which on-farm mitigation measures can cost-effectively reduce the impacts of water pollution on river ecology while maintaining food production capacity.
The River Wensum has been chosen because it is one of the most important chalk river habitats in the country with over 100 aquatic plant species and a rich invertebrate fauna. The 71-km length of the Wensum is protected under national and European environmental legislation yet, of the 90.6 ha of ‘River and Stream’ habitat included in the Site of Special Scientific Interest (SSSI), 99.4% is considered to be ‘unfavourable and declining’, mainly because of sediments, bank poaching and diffuse water pollution from various sources such as agriculture, road runoff and sewage works. It is the aim of researchers in the Wensum DTC to combine expertise in water quality monitoring with the support of agricultural experts at Salle Farms and in the agricultural industry to test measures intended to reduce the environmental impacts of arable farming. Such impacts are common in the Wensum catchment and much of East Anglia.
The research design employed in the Wensum DTC Project, features automatic water samplers and bankside monitoring stations, located at the outlets of mini-catchment areas draining the Salle Estate above Stinton Hall Farm and Park Farm. An automatic weather station, soil moisture probes and multi-level boreholes complete the monitoring network. Telemetry systems provide the ability to interrogate stream flows, water quality changes and weather data collected at 15- and 30-minute intervals using GPRS networks. This high-resolution monitoring provides detailed insight into the processes affecting the delivery of nitrate, phosphorus and suspended sediment to water courses from agricultural land and road runoff. Since the start of monitoring in October 2010, a long-term dataset is now established against which to test the introduction of measures to reduce the impacts of agricultural runoff and also to improve soil health.
A risk to water quality following harvest is the loss of residual nutrients, especially nitrate and phosphate, from the soil horizon at the onset of autumn rainfall. This is especially the case where the land is ploughed prior to sowing spring crops. The additional risk of sediment loss and the removal of topsoil from field surfaces is also potentially detrimental to long-term soil quality. A measure to counter these effects is to plant a cover crop and to introduce reduced tillage practices.
As part of the Wensum DTC Project and with the close cooperation of Salle Farms, nine fields have been selected for experimentation with cover crops and strip tillage. In the first year, 2013-14, seven of these nine fields occupying 102 ha have been sown with oilseed radish (PHOTO 3) to be followed by spring beans. In subsequent years until 2017, strip tillage will be used in the establishment of autumn-sown crops. The remaining two fields of 41 ha will act as a control and will be managed under conventional farm practices (no cover crop and with variable depth cultivation). Researchers from UEA will monitor water quality in soil profiles, field drainage and stream flow in response to the introduction of these mitigation measures to assess the benefits in comparison to other important factors such as workability of the measures and crop yields.