Potential production impact of lower N loading in Welsh dairy farming

Under the new Water Resources (Control of Agricultural Pollution) Regulation there are limitations of the total amount of N from livestock manure that can be applied on a holding.

These will be enforced from 1 January 2023. The limit is 170kg N/ha and includes manure deposited by grazing animals directly on the land or by spreading.

The amount of nitrogen produced by livestock is calculated from the table supplied by Welsh Government in the regulations (Schedule 1).

To meet the limit of 170kg N/had, the average stocking density would need to be no more than 2.13 animals per ha including all dairy animals. This is based on figures in Schedule 1, the current composition of the Welsh dairy herd[1] and assuming an average yield of 8,300 litre per annum.

This equates to a LU stocking rate of 1.67 LU per ha, on the basis of the current age structure of the Welsh herd.

The average stocking density for dairy farming in Wales for 2022 is not known, although comprehensive information on this was collected for the Welsh Conditional Aid (WCA) programme (relates to 2015/16).

Based on the WCA data, the average stocking density on Welsh farms in 2015/16 was 2.56 animals per ha. Applying this to the weighted N produced from the current Welsh herd would suggest 204kg of N is produced per ha, above the new limit by 20%.

To meet the new limit of 170kg of N per ha, the stocking density would need to reduce by 17%, when accounting for all animals, but excluding any other source of nitrogen such as slurry spreading.

Assuming that the stocking density is lowered strictly through reducing the number of animals in the enterprise, this would lead to an equivalent reduction in milk production of 17%, equating to 336m litres[2].

It is difficult to predict how dairy farmers will adapt current practices to reduce the amount of N produced on farm, but it is likely to be through a combination of the options, some of which are listed below:

• Reduce herd size
• Lower yields
• Sub-contract calf rearing
• Increase area used for enterprise

Using the relevant figures for nitrogen production per animal in Schedule 1 and the current age structure of the Welsh herd as of 1 January 2022, each of the 442,080 cattle produce 80 kg N/year and each of the cattle is equivalent to 0.784 livestock units.

[1] See Table 1

[2] Based on cow numbers and yields for the 2021/22 season. Yields for Wales are calculated based on estimated Welsh milk production and BCMS figures for the Welsh milking herd.