05 June 2015
Changes in model algorithms since Version 1.3:
Waste stream
• Waste generation algorithms for Piggery, Dairy and Feedlot removed with the view of implementing a simpler waste estimation module supported by PIGBAL, DAIRYBAL and BEEFBAL models.
• Added zero storm water infiltration as a storm water infiltration option for the STP waste generation option.
Pond
• Improvement in the calculation of the required active volume which may have some impact on the desludging of anaerobic ponds and the minimum pond water volume required for irrigation if a one-pond anaerobic system.
• Added in the reporting of smaller-volume pond overflow events.
Irrigation
• Fixed the reading in of the PAWC trigger irrigation value units incorrectly as fraction
• Fixed the reporting of irrigation reuse percentage when it is 100% reuse.
Soil
• Soil water deficit – based irrigation now calculated based on the soil water deficit of whole defined soil profile rather than rooted profile.
• Fixed error in calculations which had a small impact on the soil temperature prediction
• Soil evaporation algorithms rewritten.
Nutrient
• Added a factor to the denitrification algorithm to more explicitly account for depth of soil carbon.
• Fixed error in calculation of ammonification algorithm. The impact is very small.
• Phosphorus adsorption isotherm convergence failure minimised by increasing the convergence threshold from 1.0e-7 to 1.0e-6. This results in a slightly different equilibrium point for sorption and solution phases, resulting in small differences in annual average soil phosphorus predictions.
• Removed potassium from MEDLI.
Plant
• Plant death algorithms rewritten to reduce the severity of extreme temperatures, water and nitrogen stress on plant death to be more realistic. Added in a more realistic frosting algorithm that shows gradual plant cover loss from frost rather than a complete kill as in V1.3. This has large impact on crop and pasture growth, particularly under unfavourable environments.
• Initialised plant stress to indicate zero stress on sowing.
• Fixed errors in the calculation of the saturation stress index and water stress index.
• Fixed error in crop rotation trigger window so that rotation is triggered correctly.
• Added new option of starting crop or pasture as mature to bypass the establishment phase. Useful for crops such as vetiver where establishment phase is inadequately modelled by the current model.
• Initialised root depth to start at 100 mm rather than 0 mm, with irrigation triggered based on a minimum root depth equivalent to first soil layer rather than the first two soil layers, to improve plant establishment.
• Fixed error in the calculation of the extended thermal time required for plant establishment after sowing.
• Plant nutrient algorithms rewritten to include luxury nitrogen and phosphorus consumption in crops as well as pastures.
• Improved simulation of fallow.
Salinity
• Fixed the calculation of average soil salinity and salinity at base of profile for situations where the simulation has some (not all) years with zero deep drainage.