Project code: D-27-05
Duration 2 months - Completion date May 2005
Team and Leader M Porter, C Ferris, T Yan and C S Mayne
Organisations iInvolved Agricultural Research Institute of Northern Ireland
Background and Summary
Under the Proposed Action Programme Measures for the protection of Northern Ireland's Waters, in response to the EU Nitrates Directive, a single value of 91 kg manure N output per dairy cow per annum has been adopted for Northern Ireland. However, there is evidence from the Agricultural Research Institute of Northern Ireland that in some production systems, particularly low input and organic herds, levels of manure N output are considerably less than 91 kg/cow/year.
Indeed, provision is made for this within the Proposed Action Programme which indicates that "Use of lower figures in calculating manure nitrogen inputs would, however, require technical data to justify the lower values and these would form part of record keeping required under the Directive". It is important that such production systems are encouraged in the future, but this will require an evidence base i.e. the need to demonstrate a lower manure N output. Previous research within a related AgriSearch project has demonstrated that N intake is very highly correlated to manure N output. Consequently it is possible to accurately predict manure N output providing total N intake can be accurately assessed. The objective of the current proposal is to develop a prediction system for manure N output from dairy cows based on feed and forage analysis and animal performance data.
Wednesday 4 May, 2005 - Final prototype model (Excel version) with Final Report to AgriSearch.
Final Report will include:
(a) Details of all assumptions and biological relationships used within the model.
(b) Worked examples of the model based on different dietary inputs and determined manure N outputs
A significant number of milk producers in Northern Ireland operate low input/moderate output milk production systems and consequently these herds produce less than the 91 kg manure N output/animal assumed for average herds in the Proposed Action Programme. In order to encourage production systems with lower manure nitrogen output, there is provision within the Proposed Action Programme for use of lower figures (subject to record keeping and technical data).
Use of lower values for manure N output would have a significant impact on land requirement to comply with the 170 kg N/ha limit. For a 100 cow herd, a manure N output of 85 kg/cow would reduce land requirement (for cows only) by 3.22 ha (8 acres). Assuming 15% of Northern Ireland dairy farmers adopt low N input/low manure N output systems and reduce manure N output by 6 kg/cow, the total saving in land requirement = (43,500 cows x 6 kg manure N) divided by 170 = 1,535 ha (3,794 acres).