The scientific model behind OverseerFM calculates and estimates the nutrient flows in a farming system and can be used to identify potential risks of environmental impacts through the calculation of nutrient loss such as run-off and leaching, and greenhouse gas emissions (including methane (CH4), nitrous oxide (N2O), and direct and embodied carbon dioxide (CO2)).
The core of the model is a nutrient budget - OverseerFM calculates nutrient budgets for N, P, K, S, Ca, Mg and Na at farm and block level. A nutrient budget is a table of inputs and outputs for a nutrient, for a particular physical identity (e.g. a farm or a block). A diagrammatic example of a nutrient budget is shown in Figure 1:
OverseerFM also provides an estimate of:
- Maintenance nutrient and lime requirements.
- RSU (revised stock units) and RSU per hectare for each enterprise
- Monthly pasture production and animal DM intake
- N-pool graphs
- GHG emissions by source and per product
- carbon sequestration
- N surplus and nitrogen conversion efficiency
- Effluent report
- National benchmarking
- Aggregated group reporting