Table 4.

The percentage (%) of optimisation runs for which each modelled ‘first filter’ measure was included in optimal measure combinations to meet the prescribed pollutant load reduction targets of 2% in the Demonstration Test Catchments (DTCs).

Control measure	Avon	Eden	Tamar	Wensum	All DTCs
Use a fertiliser recommendation system	19	16	17	17	17
Do not apply manufactured P fertilisers to high P index soils (with an Olsen soil P index of 4 or above)	17	15	15	14	15
Establish cover crops in the autumn	6	11	11	17	13
Site solid manure heaps away from watercourses/field drainsa	4	3	3	11	6
Do not apply manufactured fertiliser to high-risk areasa	4	8	7	2	5
Do not spread slurry or poultry manure at high-risk timesa	6	5	4	4	4
Do not apply manure to high-risk areasa	4	5	4	4	4
Establish riparian buffer strips	3	6	5	1	4
Fertiliser spreader calibrationa	2	3	5	3	4
Manage over-winter tramlines	1	6	3	2	3
Reduce field stocking rates when soils are wet	1	0	4	7	3
Reduce the length of the grazing day/grazing season	4	3	2	7	3
Avoid spreading manufactured fertiliser to fields at high-risk timesa	4	3	3	1	3
Increase the capacity of farm slurry stores to improve timing of slurry applicationsa	1	0	3	4	3
Locate out-wintered stock away from watercourses	0	4	3	1	3
Incorporate manure into the soila	1	3	2	0	2
Move feeders at regular intervals	0	0	2	2	1
Fertiliser sprayer calibration	2	3	0	1	1
Establish and maintain artificial wetlands - steading runoff	1	0	1	1	1
Intensive ditch management on arable land	0	0	2	0	1
Avoid irrigating at high risk times	0	0	1	1	1
Intensive ditch management on grassland	0	0	0	0	0

^aMeasures covered under 2012 regulation or statutory management requirements (SMRs e.g. NVZ Action Programme rules).