In this project, a farm balance for carbon and nitrogen for the years 2020 and 2021 was calculated for the farm of the Grottenhof agricultural college near Graz. The organic farm has 50 ha of agricultural land with grassland for hay and silage, arable land for concentrated feed and food grains, as well as 45 LSU of cattle (dairy cows and calves, compost barn). There is intensive cooperation (animals, fodder, machinery, etc.) with a second farm site in Hardt (6 km away).

The carbon and nitrogen balances showed that about two thirds of the carbon and nitrogen in the feed remain in the manure and thus in the farm cycle after being utilised via the cattle.

The highest amounts of carbon and nitrogen per ha and year at Grottenhof came from the clover grass and alfalfa areas.

Considerably more nitrogen was received at Grottenhof via legumes (especially fodder legumes such as clover grass and alfalfa) than via farm manure. In addition, legumes also add a lot of carbon into the soil for an increase in soil organic matter.

With an input of about 8,000 kg of fossil C (32,000 kg of CO2), about 50 hectares are cultivated annually at Grottenhof and over 200,000 kg of milk, 2,000 kg of meat and 30,000 kg of food grain are produced. As a by-product, fertiliser worth over 70,000 kg of renewable carbon is produced, demonstrating the value of animal husbandry in agriculture.