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The EU LIFE and Defra funded project ‘WAgriCo’ developed and demonstrated integrated catchment management in pilot catchments in Germany and England with the intention of decreasing nitrate losses to groundwater. Central to the approach was the large-scale use of a ‘Programme of Measures’. It was a supportive project, working with the local farming community, to help provide a model that others can follow.

Methods

The project consisted of 5 steps:

1. Initial Farm Assessments
2. Farm Gate Nutrient Balances
3. Water and Soil Sampling
4. Programme of Measures (PoMs)
5. Farmer Support

The farm audits and risk assessments indicated that there were few examples of severely poor practice that could be immediately identified as the main cause of diffuse pollution problems within the catchment. It was considered that much could be tackled by focusing on good agricultural practice (GAP) and by helping farmers understand the linkage between farm practices and N loss. A total of six measures were compiled which form the PoMs for the priority catchments within the study area; fertiliser recommendations (including soil testing), enhanced manure management plan, cover crops, fertiliser spreader calibration, moving from autumn to spring application of manures and encouraging the use of N efficiencies as a management tool.

Out of the 74 farms targeted by the project, 52 (70%) agreed to participate. The uptake of the measures was influenced by the individual farming systems, for example the predominant use of winter crop rotations made the use of cover crops inappropriate for many.

Results

In general there was no large scale over-supply of nitrogen (as fertiliser plus manure) to crops in the catchments. The main problem centered around a relatively few maize fields - where the nitrogen content of the large manure applications were not taken into account when deciding on fertiliser N dressings. Where manures were applied to other arable crops, there was recognition of their nitrogen value. Grass fields generally received less N than would be recommended.

Cover crops were established by farmers over the 2007/08 winter period. The SMN results suggest that the use of a cover crop within the WAgriCo priority catchments can reduce the amount of N lost over the winter period by approximately 15 – 30 kg ha-1, this is however only based on data from one winter.

Figure 1. Comparison of N loss over winter 07/08 between forage maize fields with and without a cover crop

Results from fertiliser spreader calibration showed that one in five machines tested required calibration for application rates to be correct. The average coefficient of variation (CV) before calibration was 22%, and, following calibration, 3%.

Plate 1. Fertiliser spreader calibration

The theoretical effects of poor spreading suggest that, for cereal crops, a relative low CV of 15% will increase nitrate leaching by 8%. This increases to approximately 13% (11kg ha-1) at a CV of 30%. These results indicate that fertiliser spreader calibration is effective in reducing nitrate leaching as well as being beneficial to the farmer, providing €14-27 ha-1 in yield improvements (based on February 2008 prices).

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