OVERSEER is a software application made up of three components, the user input fields where a farm is described, the engine that models the nutrient movements for that farm through a series of calculations and the reports which display the analysis for interpretation (and are stored in the database). All three components work together to undertake scenario analyses of different nutrient outcomes for a farm to inform management decisions. It currently requires an expert user to describe the physical and management details of a farm. The engine is made up of a series of sub-models that calculate the flow of seven major farm nutrients – Nitrogen (N), Phosphorus (P), Potassium (K), Sulphur (S), Calcium (Ca), Magnesium (Mg), and Sodium (Na) and greenhouse gases. The reports provide a full nutrient budget analysis of the farm and several other specific analyses of different nutrient movements on the farm and greenhouse gas emissions.
As with any software application, OVERSEER is updated at regular intervals - to fix known problems, improve or add features and add new science. Each release has a new version number (formatted X.Y.Z). The version number is found on the report or XML file created using that version.
Overseer Limited currently runs a six-month software release cycle to update OVERSEER every May and November. Information about each release, including predicted changes in results are provided to users in release notes published in MyOVERSEER.
The OVERSEER model has been expanded over time (see development history timeline) to cover a wide range of different farm enterprises and management practices in New Zealand. It can model mixed and single enterprise farms of varying intensity and with or without irrigation.
Farm types currently modelled by OVERSEER include:
Pastoral enterprises including dairy, beef, sheep, dairy goats and deer. These include farms using fodder crops (fodder beets, kale, rape, swedes, turnips), forage crops (ryegrass, barley, oats, maize, rye corn, triticale) and animal housing.
Permanent fruit crop enterprises including avocado, kiwifruit, apples, peaches and grapes.
Horticulture enterprises including:
Arable crop enterprises including:
As well as providing nutrient budgets, OVERSEER supports farm management decisions by:
Over time, OVERSEER, has also been developed to:
OVERSEER adds value to farm management decisions because it predicts the outcomes of changes in managing nutrients. Because OVERSEER provides an individual analysis of a farm, it helps users identify the best ways to manage that farm and mitigate potential losses of nutrients into the environment.
The following summary details farm inputs having the most influence on nutrient loss estimates:
|Category||Variable||Effect on calculated||Ability of farmers to influence|
|Production and Reproduction policy||×||×|
|Fertiliser||Fert N rate||×||×|
|Fert N form||×||×|
|Fert P rate||×||×|
|Fert P form||×||×|
|Supplements||Farm grown supplements||×||×|