This model shows some of the interdependencies between systems on a dairy farm. Cows need water and feed and are housed in a shed. They produce milk which is sold at a market rate selectable by the user.

Cows also produce effluent and by recycling the waste with a bio-digester, the farm can utilize the recycled water for crop irrigation and for aqua farming. Biogas collected from the cow shed can be used to generate electricity.

Run the model for different settings of the slider controlling the number of cows on the farm. Compare the annual income generated on the farm by activating the bio-digester. The daily results show the milk production, income and expenses for the current day during the simulation run.

The simulation also estimates the Global Warming Potential (GWP) by considering carbon and nitrogen levels during operation.

Note: We made a simplistic assumption that when the cows do not receive adequate water and feed they stop producing milk. As soon as water and feed become available, milk production is resumed.