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Overseer is a science model made up of three components:
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:
To ensure Overseer is generating expected results, like other models it is calibrated against measured data. In 2012, when the nitrogen (N) pastoral grazing model embedded in Overseer was revised to capture newly developed science on urine patch dynamics, it was calibrated against farmlet-scale N leaching measurements.
Since then there have been a number of potentially significant changes to the model, including the incorporation of the new irrigation sub-model (version 6.2) and changes to feed allocation for seed crops and ME modelling.
The new FM software includes facilities to test detailed measured data against modelled results (including individual sub-models within Overseer) making it possible to assess the modelling against more data (including lysimeter trials) that have become available since 2012.
Overseer Limited currently has a N-loss through leaching calibration project underway and one in preparation.
We are currently preparing to undertake a calibration of the N-model for Arable systems using the data that has become available from a fluxmeter network that has been in place in New Zealand for the last few years. This data is provided by the Ministry for the Environment, Foundation for Arable Research, Plant and Food Research and other funding partners.
This includes 12 farms in Canterbury, Manawatu, Hawkes Bay, Waikato and Pukekohe regions with arable and vegetable rotations including grains and seeds, onions, maize, potatoes, beetroot and leafy green vegetables – the results still need to be assessed before we can confirm they are able to be used successfully in this process. We are also working with Zespri to assess data from Kiwifruit trials.
Subject to confirming arrangement with required experts we are planning to undertake this work in the next 6 months
As with any software, Overseer is updated at regular intervals - to fix known problems, improve or add features and add new science to the science model. When updates are made to the science model, the model version number changes. The version number can be found on the top right of the farm analysis page in OverseerFM.
The current version number is 6.3.1. The number format represents the scale of change
Overseer adds value to farm management decisions because it predicts the outcomes of changes in farm management on nutrient loss. 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 identifies the farm management areas that have 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||×||×|