26 01 2021

LIFE DOP :Demonstrative mOdel of circular economy Process in high quality dairy industry

The LIFE DOP project (Demonstrative mOdel of circular economy Process in  high quality dairy industry) is a EU project, located in Mantua district, in the middle of the cheese production chain, aiming to demonstrate a new production model for Grana Padano PDO (Protected Designation of Origin) and Parmigiano Reggiano PDO, able to reduce the environmental impacts of production. As literature clearly outlines, (Thoma et al., 2012, IPCC 2006) a relevant area of GHG emission in milk production is the management of slurry and of nutrients, and these are key areas in which is important to invest to reduce burdens.

The main aims , actions and results of the project are described as follows:

Valorisation of manure in the energy sector (biogas)

Slurry Exchange Platform: the project implemented a Slurry Exchange Platform able to collect slurry, manure and slurry derived fraction from small dairy stables and to valorise them in anaerobic digestion plants of different owners. The web platform runs linking supply and demand and providing logistic organization for transport and bureaucracy compliance. Slurry and slurry-manure derived fractions (shredded manure, separated solid fraction of slurry and cavitated slurry-manure mix) were sent to anaerobic digestion plants. The biogas plants replaced the amount of energy crop they were using with the slurry-manure derived fractions (up to 70%). Trust was built among biogas plants owners, as the products delivered to their facility was certified, high quality and almost constant for methane production and particle size. During the project a specific prototype device was built (mobile cavitator) to facilitate the management of the manure and manure fractions in anaerobic digestion plants. It is to remark that the biogas plants were built and run for using energy crop up to the moment of substitution. The result of the activity was that, even if the stables are small and cannot afford a large-scale biogas plant, they nonetheless benefit from the advantages of anaerobic digestion, nutrient recovery and nutrient export.

Environmental achievements: In almost 4 years of project more than 110.000 ton of slurry and slurry-manure derived fractions were sent to 10 biogas plants, 30 million KWh of renewable nergy were produced, 750 ton of methane emission form slurry storage were avoided. Including the renewable energy produced, the total CO2 eq. saving were equal to 30.000 tons. The total carbon footprint of milk production was reduced by 8-13% in the stables involved.

Economic outcomes: the farmers (more than 80 stables involved) were given reward for providing the slurry and slurry derived fractions: from 2 to 4 euros/ton according to the processing steps (e.g. slurry separated fraction, higher in dry matter and methane potential, were rewarded more). The biogas plant owners saved up to 30% of the cost of the feeding mix in comparisons with maize. Two of the facilities were monitored in order to detect possible failure, loss of productivity or side effects of the substitution of energy crop by slurry derived fractions, and no problems were detected.

Contribution to nutrient recovery and management: The amount of nutrients concentrated in the solid digestate (N and P) was 3 times higher than digestate coming from maize. The higher content of nutrients makes these materials more valuable for the export in non-livestock areas (organic farming, horticulture, orchards) compared to slurries or standard digestate.  More than 25.000 tons of recovered renewable fertilizers were exported in non-livestock areas, substituting chemical fertilizers. Trials in demo field in non-livestock areas demonstrated that that it is possible to reduce by 100 kg /ha the synthetic nitrogen fertiliser used thanks to the distribution of solid digestate in the autumn, and the production was slightly higher than control (standard fertilization with urea).

The Slurry Exchange Platform demonstrated on the ground the possibility to increase the sustainability of the cheese production, to allow the export of excess nutrients of intensive livestock areas, and to better manage the nutrients locally, i.e. to zeroing the use of urea for crop and valorise the use of digestate by pre-sowing and coverage distribution.

Virtuous management of the digestate in the field and reduction of mineral fertilizer (circular economy)

The aim is the proper and sustainable management of nutrients and carbon in fields as an essential step to improve the overall sustainability of the milk production chain, by effective and precision use of recovered nutrients (digestate) and zero chemical input.

Demo-field activities allowed to test the use of solid digestate in non-livestock areas, decreasing the synthetic fertiliser input by 100 kg /ha respect to reference practice (Demo farm 2).

The liquid fraction of digestate was valorised locally with higher efficiency than the slurry and manure fractions before anaerobic digestion. Again, trials in demo field demonstrated that that it is possible to zeroing the synthetic nitrogen fertiliser used in livestock areas and apply the liquid digestate with increased efficiency by injection or drip irrigation in pre-sowing and coverage.

The injection reduces ammonia emissions by 40% compared to traditional distributions use of slurry by splash plate and urea in coverage).  Fertigation with digestate is extremely efficient in the distribution of nutrients, reduces ammonia emissions and overcomes the problem of entering clayey soils with heavy machine.

Digestate solid fraction in LIFE DOP model is always exported to rebalance nutrient load in livestock areas

Optimization of stables management

The objectives and activities of  the action are to collect data about stables management, elaborate data and outline weak points, thus propose optimisation procedures to improve sustainability.

The analysis of data from over 90 companies has shown that there is a wide gap between virtuous companies and “less optimized” companies. Less optimized companies have up to 50% higher carbon footprints than optimized companies.

The area to be optimized concern the feeding of the animals (quality and quantity), the procedures and protocols for the management of the phases of life (dry, calving, etc.) the buildings and devices that allow to increase animal welfare, the monitoring of the single herds by specific devices of “precision breeding”. These improvements lead to greater efficiency and a lower environmental footprint.

10 companies have been followed in specific improvement plans, achieving an average reduction in the carbon footprint of milk production by 15%.

The improvement plans have shown to the farmers the importance of the correct and constant measurement of parameters such as fodder production and feed consumption, to better plan the production activity and to prevent or solve problems. Moreover, it outlined the need for a technical assistance service, which continually updates the companies on the knowledge that the research provides for increasingly profitable and environmentally sustainable milk production. Several breeders have also expressed the need to have a qualified and neutral advice (not linked to the sale of products), to improve their technical-economic and environmental results, so that two other companies, not initially included in the project, have asked to be included as pilot companies for improving their current practice.