How does low-input and organic farming affect the environment?
Low-input and organic dairy farms in general have a higher share of grassland than conventional, high-input farms. This is beneficial in regard both to the biodiversity in the fields and to the carbon level in the soil.
Although the impacts of the agricultural production on biodiversity and the built up of carbon in the soil are crucial factors from an environmental perspective, these two factors have until now not been included in the Life Cycle Assessment (LCA) used to assess the environmental impact of milk production.
Therefore the SOLID scientists have developed a new method for calculating the LCA including both factors. This is in particular important in regard to the organic milk because organic dairy production in general has no damaging effect on biodiversity contrary to milk from conventional production.
Also, organic farms usually have a higher soil carbon sequestration because of the higher share of grassland in the rotation. Since this is one of the main features of organic farming, it is very important also to include carbon sequestration in the carbon footprint calculations.
So, the new method to calculate the Life Cycle Assessment provides a more comprehensive and unbiased picture of the environmental impact of milk production by reducing the calculated carbon footprint of organic milk.
Read more in the SOLID Technical Note:
Carbon footprint and biodiversity assessment in dairy production
The impact of milk production on climate change can be calculated as a ‘Carbon footprint of milk’.
Definition of carbon footprint of milk
The sum of all the greenhouse gas emissions – methane, carbon dioxide and nitrous oxide from the dairy farm and other related upstream processes divided by the amount of milk produced at the farm.
Smaller carbon footprint of organic milk than of conventional
Calculation of carbon footprint does normally not include soil carbon sequestration. So in order to develop the new LCA calculation method the SOLID scientists first calculated the carbon footprint of 23 organic dairy farms in the UK, Denmark and Finland with the usual LCA method without including soil carbon sequestration. The carbon footprint was also calculated for the average conventional dairy production in order to compare.
When using this traditional method, the carbon footprint of milk turned out to be around 1 kg CO2 equivalents per liter milk. The carbon footprint of organic milk varied from farm to farm with no clear pattern and there was no significant difference between organic and conventional production.
Then the next step was to include soil carbon sequestration in the LCA-calculations. This changed the picture. Now, the carbon footprint of the organic farms was reduced while the carbon footprint of conventional milk was not affected. The main reason is the higher share of grassland on organic farms. Conventional farms for their part, have a higher share of maize and cereals than the organic farms.
Better biodiversity on organic farms
Another main difference between organic and conventional farms is the higher biodiversity on organic farms. Yet, the impact of agricultural production on biodiversity is normally not included in environmental Life Cycle Assessment either.
Based on biodiversity data from farms in seven EU countries, the SOLID scientists developed a method also to include the loss of biodiversity in the LCA calculations using the number of plant species as an indicator for biodiversity.
In short, this methodology is based on a potential loss of plant species in a field compared to a more natural vegetation, namely the vegetation in a semi-natural forest.
How to assess the loss of biodiversity
- A typical semi-natural forest has 20 different plant species per 100 square meters
- A typical conventional cereal field has 6 different species.
- The difference indicates a loss of 14 species
- The biodiversity loss is then calculated to be 70 per cent (0.70)
In organic cereal fields the loss is only approximately 0.20 and in both conventional grasslands the loss is only approx. 0.10.
In organic grasslands the number of plant species is even higher than in the natural vegetation (semi-natural forest). The loss of biodiversity is approximately -0.30, meaning that the number of plant species is 30 per cent higher compared to natural vegetation.
The calculated biodiversity losses for each crop are based on registrations of plant species in different crops across Europe.
Loss of biodiversity
- Semi-natural forest 0 per cent (1.00 – index)
- Conventional cereal field 70 per cent loss, (0.70)
- Organic cereal field 20 per cent loss, (0.20)
- Conventional grassfield 10 per cent loss (0.10)
- Organic grassfield 30 per cent gain (-0.30)
When the SOLID scientists developed the new Life Cycle Assesment methodology, the calculated numbers for each crop was used to calculate a Biodiversity Damage Potential for the milk production on the 23 farms in the UK, Finland and Denmark. Depending on the share of grass, cereals and maize in the cows feed ration, the Biodiversity Damage Potential for each farm is shown with red dots in the diagram above.
Many of the organic farms had a negative Biodiversity Damage Potential, which means that the biodiversity on the farm is higher than that of a semi-natural forest.
These results from the SOLID project show how important it is to include both soil carbon sequestration and biodiversity in the environmental assessments in order to give a more precise picture of the actual environmental impact of the milk production.