Nitrogen loading and stocking rates

Implementation of the Nitrates Directive requires a number of measures to reduce or prevent nutrients from agriculture entering our waterways. One such measure will limit the amount of manures that can be applied. For any farm, the amount of total nitrogen (N) in organic manures applied to the land, including by the animals themselves, and that brought onto the farm, shall not exceed 170kg N/ha/year. So how does this relate to the stocking rate on a dairy farm?

In Northern Ireland, due to the range of intensity with dairying systems, the impact of the 170kg N/ha limit varies. The table below assumes a specialist dairy farm with a 30 percent replacement rate and shows the relationship between organic loading and stocking rate.

Level of organic N/ha	Approximate stocking rate LU/ha	Percentage of benchmarked farms below stocking rate
150 kg	1.76	20
170 kg	2.00	41
190 kg	2.24	66
210 kg	2.47	81
230 kg	2.70	92
250 kg	2.94	96

In conjunction with College of Agriculture, Food and Rural Enterprise (CAFRE) Development Advisers, dairy farmers can benchmark their enterprises within the farm business against other similar farms throughout Northern Ireland. The average benchmarked dairy farm has a stocking rate of around 2.09 LU/ha. Approximately 41 percent have a stocking rate equivalent to less than 170kg N/ha. For those above the 170kg N/ha limit they should consider one of the following:

The availability and cost of additional land, stock type and stock profitability will influence the option taken.

The Department of Agriculture and Rural Development, in conjunction with the Department of Environment, are actively seeking derogation for those farms that wish to operate above the 170kg organic N/ha. The table shows that a derogation of 230 kg organic N/ha would be sufficient for over 90 percent of dairy farms to operate without a stocking rate restriction. If Northern Ireland was successful in securing a derogation, farmers would apply for this on an individual basis, however more stringent additional measures would have to be adhered to in order to compensate working at a higher organic N limit. Also, farmers would still have to adhere to the phosphorus surplus P targets, and this may restrict them from fully availing of the higher N limit.

The full Nitrates Directive Consultation Paper on the proposed Action Programme measures is available from; www.dardni.gov.uk or the Department of Environment (028) 9025 7365. If you wish to comment on the proposals, the closing date for comments is the 16 May 2005.