Farm Advisory Service

Methane production and what can we do about it?

Depending on body size and nutrition, dairy cows can produce up to 500 litres of methane (CH4)/day, contributing between 4550% of a dairy farm’s carbon footprint (CFP). Methane mainly comes from enteric fermentation, the natural process of fibre digestion in the rumen. Measures to reduce total CH4 emissions, as well as per kg of milk, include:

1. Forage quality – the higher the better. Higher D value (digestibility) forages have a lower fibre content, meaning less CH4 production during rumen fermentation. They also enable higher intakes, leading to more milk output and so less CH4 per kg of milk. Cutting date will have the biggest influence on forage quality.

2. Increase concentrates – feeding more concentrates in place of silage will reduce CH4 production. Concentrate type is also important as those with a higher NDF (fibre) content e.g., sugar beet pulp and soya hulls, will produce more CH4 than starchy, lower NDF cereals and some protein sources. A milk yield response is also likely, again reducing CH4/kg of milk.

3. Age at first calving – this can have a significant impact on total herd emissions as dairy heifers will be producing CH4 but have no milk output to spread emissions over. Research by AFBI showed that reducing calving age of heifers from 27 to 24 months reduced the CPF by 7% for a typical moderate input herd in Northern Ireland.

4. Replacement rate – reducing the replacement rate means less heifers are required to maintain herd size. Longevity also improves as a typical 33% replacement rate means a cow lasts for three lactations, but this increases to five lactations with a 20% replacement rate. Focus on health and fertility to reduce replacement rate and heifer requirements.

Not only will these improvements reduce a farm’s CFP, but they should also bring financial benefits.

LEMKEN conducts carbon farming research project

LEMKEN has developed the concept of a Carbon Farming Plough in collaboration with the Leibniz Centre for Agricultural Landscape Research (ZALF). The ZALF research work on yield and climate effects of partial deep tillage are funded by the German Federal Ministry of Food and Agriculture. LEMKEN will use this research to create an implement for carbon enrichment in arable soils that is ready for series production.

This plough is intended to be used for meliorative tillage, i.e. to break up compaction and improve the soil as a result. The implement features bodies which plough at alternating depths to create wells below the tillage level in every other furrow, which are then filled with humus-rich topsoil. Analyses of historical trials conducted by the ZALF have shown that more than half of the humus introduced in this manner is retained to secure the long-term storage of CO2 in the soil.

The lower soil layers with little humus which are ploughed up in the process are mixed with the topsoil and form new humusrich topsoil within a matter of only a few years, as carbon is introduced from crops. Overall, the humus content of soils tilled in this manner therefore increases, and soil fertility improves. At the same time, this sustainable soil improvement creates up a new business model in the form of carbon farming.

Breaking up compacted soils while also introducing humus-rich topsoil into wells allows plant roots to grow into deeper soil levels and access the water and nutrients retained there. This approach can increase yields by up to five per cent even in the first year. This effect was established as early as in the 1960s and 1980s and has been confirmed by recent field trials conducted by the ZALF. The method can be repeated diagonally to the main direction of work after five to ten years. In addition to the above benefits, this new carbon farming technology also opens up new income streams for farmers in the form of trade in CO2 certificates. A potential future tax on CO2 emissions is therefore avoided, and the competitiveness of agricultural businesses is improved.

Elrick Prize recognises work to improve sustainability -

Alex Pirie has been awarded the inaugural Elrick Prize in recognition of his work to improve land sustainability

A new annual prize has been created by SAC Consulting – part of Scotland’s Rural College (SRUC) – in memory of Senior Consultant Gavin Elrick.

Gavin, who was part of SAC Consulting’s Environment Team, helped Scottish agriculture become more sustainable by sharing his vast knowledge with farmers and crofters across the country. His untimely death in November 2020 came as a shock to colleagues and the wider rural community.

The inaugural Elrick Prize has been awarded to Consultant Alex Pirie in recognition of his work to improve the sustainability of land use.

Alex, who is from a dairy farming background near Campbeltown, is already well regarded across the business and with many farming stakeholders.

He was nominated by Principal Consultant Chloe McCulloch and seconded by Regional Development Manager Raymond Crerar.