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Manure Manure N Loading & P Balance

Agriculture

Manure N Loading & P Balance

The CAFRE dairy farm extends to 161.7 hectares. Land use on the farm includes grassland (72.3%) and an arable rotation of forage maize, cereals, and potatoes on a proportion of the land. The breakdown of land use in 2017 was as follows:

Grassland 117.0 ha
Forage maize  12.8 ha
Wholecrop wheat 10.0 ha
Potatoes and combinable cereals 21.9 ha
Total farm area  161.7 ha

Best practice in nutrient management planning is applied on the farm with soil analysis undertaken on all land on a three year cycle. Slurry and farmyard manure are applied to grassland and crops to optimise use of the nutrients contained in these manures and to minimise the need for chemical phosphorus (P) fertiliser.

As the grassland area is less than 80% of the total farmed area, the CAFRE Dairy Farm, which includes 21.9ha of arable crops, is not eligible for a Nitrates Directive Derogation. Therefore, the overall livestock manure nitrogen (N) loading on the farm is maintained below the 170 kg livestock manure N limit. The actual N loading was 149 kg N/ha in 2017 as detailed in the PDF document in the Additional Information section on this page.

However, within the whole farm, the dairy enterprise is managed to demonstrate compliance with the requirements of a Nitrates Directive Derogation. The total forage area utilised by the dairy cows and replacement heifers is as follows:

Grassland 117.0 ha
Forage maize  12.8 ha
Wholecrop wheat 10.0 ha
Total farm area  139.8 ha

The farm ‘forage area’, livestock stocking rate was 2.2 cow equivalents per hectare in 2017. The dairy herd grassland area was 83.7% of the total forage area. The livestock manure N loading across the dairy herd forage area was 173 kg N/ha and the P surplus was 5.0 kg P/ha. No chemical P fertiliser was applied to the grazing and silage areas with all of the grassland phosphorus requirements being met with slurry. High quality grass is grazed and ensiled to make high quality silage, optimising milk from forage and reducing concentrate feed requirements to keep the forage area P surplus well below the derogation requirement of 10.0 kg/ha.