A statement assumed to be true within the OVERSEER model.
The sum of areas of the farm that are managed the same (e.g. irrigated, cropped, effluent applied) and have the same bio-physical attributes (e.g. soil type, topography).
The process of adjusting numerical or physical modelling parameters in the computational model for the purpose of improving agreement with experimental data.
Design criteria:
The explicit goals that have determined the model’s structure.
All quantitative and qualitative methods for evaluating the degree to which a model corresponds to reality.
Calculation model within OVERSEER. This uses inputs from an interface or file and produces the outputs.
Within OVERSEER enterprise refers to the animal types present on farm, e.g. dairy, dairy replacements, sheep, beef, deer, dairy goats, and others are recognised.
Land use:
The management unit of interest. OVERSEER models pastoral, horticultural, arable and vegetable land uses and these land uses can all be integrated into one OVERSEER nutrient budget if required.
Something that bounds or restricts the models’ use.
Seven nutrients are modelled in OVERSEER; nitrogen, phosphorus, potassium, sulphur, calcium, magnesium and sodium. Within the pastoral model, change in acidity (H+) is included for the determination of lime maintenance requirements.
Nutrient budget:
Report of net inputs and outputs to a given scale (block, farm), defined system over a fixed period of time.
Nitrogen conversion efficiency or Nitrogen Use efficiency:
product N / N input, where N inputs include fertiliser, supplements and N fixation.
Nitrogen surplus:
The difference between inputs and removals by plants.
Nutrient transfer:
Spatial and temporal movement of nutrients between locations on a farm, e.g. effluent applied to a block, or nutrients being consumed in one place and deposition as excreta in another.
the software that comprises the engine plus input data (interface) and data storage systems.
The model assumes that inputs and farm management practices described are in quasi-equilibrium ‘steady-state’ with the farm production.
Relative yield:
Predicted relative pasture yield relating to nutrients applied (fertiliser).
Sub-models are a combination of science principles and assumptions that are simplified to describe nutrient use and movement. OVERSEER consists of over 20 sub-models (hydrology, climate, animal intake etc.).
The potential limitation in some part of the modelling process that is a result of incomplete knowledge.
A comparison of model results with numerical data independently derived from experiments or observations of the environment (a part of the wider evaluation)