Welcome to APSIM

NEWS

SILO Redevelopment

Are you aware that the SILO climate database has been redeveloped. The new system is now available for use. Some benefits of the new system:
• all datasets are now free of charge (supported by the Queensland Government’s Open Data initiative)
• data can now be distributed as they are licensed under the Creative Commons Attribution 4.0 licence
• users can now download gridded data (data are in NetCDF format). Please see the new web site for more information about accessing the gridded data.
• the new web interface is much easier to use than the old interface
• the new Application Programming Interface (API) enables users to query the amount of observed data available at each station
• patched point datasets are available at nearly all (18,700) stations (previously patched datasets were only available at a modest subset of the stations)

The APSIM SILO mirror based out of Toowoomba will stop working soon. You will need to switch the new SILO climate database as soon as possible.

You can find the SILO Getting Started Guide in the Technical documentation section of http://www.apsim.info/Documentation.aspx

Monday, 25 June 2018/Author: Sarah Cleary/Number of views (36)/Comments (0)/
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4th Annual ISU APSIM Training Course

Iowa State University Department of Agronomy is hosting the 4th Annual ISU APSIM Training Course - Evaluating Production and Environmental Performance of Cropping Systems with APSIM. There are 34 participants from 12 U.S. states with interest in soils, crops, and atmospheric sciences. Look for updates on Twitter with #ISUAPSIM2018.  

Tuesday, 12 June 2018/Author: Sarah Cleary/Number of views (121)/Comments (0)/
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APSIM Training

September 18-19, Brisbane

The next APSIM training course will be held at the Queensland Bioscience Precinct, St Lucia on the 18th and 19th of September.  Please send your EOI and/or any questions to apsim@csiro.au
Tuesday, 12 June 2018/Author: Sarah Cleary/Number of views (105)/Comments (0)/
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Are you having problems with APSIM or have questions?

If you are using APSIM (version 7.x or APSIM Next Generation) and think you have found a software defect, you can submit a defect report here:

If you're not sure whether the behaviour you are seeing is a defect or not, you can talk to a developer or other users by posting on the support forum: http://www.apsim.info/Support.aspx. This forum can also be used for general questions about APSIM.

If you have questions relating to commercial access to APSIM or are interesting in attending APSIM training, then you can send an email to: apsim@csiro.au

Thursday, 26 April 2018/Author: Sarah Cleary/Number of views (223)/Comments (0)/
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APSIM Training

Expression of Interest Request

We are seeking Expression of Interests for the next APSIM training course to be run in August or September 2018.  If you are interested in attending, please send an email to apsim@csiro.au.  Please include you preferred location/s. 
Thursday, 26 April 2018/Author: Sarah Cleary/Number of views (281)/Comments (0)/
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FEATURES

Using grassland models to determine sound mitigation practices while quantifying the uncertainties

APSIM was one of several models included in the work recently published in Science of the Total Environment - “The use of biogeochemical models to evaluate mitigation of greenhouse gas emissions from managed grasslands” https://doi.org/10.1016/j.scitotenv.2018.06.020

 

Simulation models quantify the impacts on carbon (C) and nitrogen (N) cycling in grassland systems caused by changes in management practices. To support agricultural policies, it is however important to contrast the responses of alternative models, which can differ greatly in their treatment of key processes and in their response to management. We applied eight biogeochemical models at five grassland sites (in France, New Zealand, Switzerland, United Kingdom and United States) to compare the sensitivity of modelled C and N fluxes to changes in the density of grazing animals (from 100% to 50% of the original livestock densities), also in combination with decreasing N fertilization levels (reduced to zero from the initial levels). Simulated multi-model median values indicated that input reduction would lead to an increase in the C sink strength (negative net ecosystem C exchange) in intensive grazing systems: −64 ± 74 g C m−2 yr−1 (animal density reduction) and −81 ± 74 g C m−2 yr−1 (N and animal density reduction), against the baseline of−30.5±69.5 g C m−2 yr−1 (LSU [livestock units] ≥ 0.76 ha−1 yr−1). Simulations also indicated a strong effect of N fertilizer reduction on N fluxes, e.g. N2O-N emissions decreased from 0.34 ± 0.22 (baseline) to 0.1 ± 0.05 g N m−2 yr−1 (no N fertilization). Simulated decline in grazing intensity had only limited impact on the N balance. The simulated pattern of enteric methane emissions was dominated by high model-to-model variability. The reduction in simulated offtake (animal intake + cut biomass) led to a doubling in net primary production per animal (increased by 11.6 ± 8.1 t C LSU−1 yr−1 across sites). The highest N2O-N intensities (N2O-N/offtake) were simulated at mown and extensively grazed arid sites. We show the possibility of using grassland models to determine sound mitigation practices while quantifying the uncertainties associated with the simulated outputs.

 

Monday, 18 June 2018/Author: Sarah Cleary/Number of views (140)/Comments (0)/
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Lateral spread affects nitrogen leaching from urine patches

The paddocks in APSIM simulations can be used to model experiments with complex geometry as shown in this example from a recently-published paper (https://authors.elsevier.com/c/1WxqtB8ccgYiR  - available free until 15 June) 

Schematic representation of a urine patch and the simpler representation of the complex geometry used in the APSIM modelling. 

Nitrate leaching from urine deposited by grazing animals is a critical constraint for sustainable dairy farming in New Zealand. While considerable progress has been made to understand the fate of nitrogen (N) under urine patches, little consideration has been given to the spread of urinary N beyond the wetted area. In this study, we modelled the lateral spread of nitrogen from the wetted area of a urine patch to the soil outside the patch using a combination of two process-based models (HYDRUS and APSIM). The simulations provided insights on the extent and temporal pattern for the redistribution of N in the soil following a urine deposition and enabled investigating the effect of lateral spread of urinary N on plant growth and N leaching. The APSIM simulation, using an implementation of a dispersion-diffusion function, was tested against experimental data from a field experiment conducted in spring on a well-drained soil. Depending on the geometry considered for the dispersion-diffusion function (plate or cylindrical) the area-averaged N leaching decreased by 8 and 37% compared with simulations without lateral N spread; this was due to additional N uptake from pasture on the edge area. A sensitivity analysis showed that area-averaged pasture growth was not greatly affected by the value of the dispersion factor used in the model, whereas N leaching was very sensitive. Thus, the need to account for the edge effect may depend on the objective of the simulations. The modelling results also showed that considering lateral spread of urinary N was sufficient to describe the experimental data, but plant root uptake across urine patch zones may still be relevant in other conditions. Although further work is needed for improving accuracy, the simulated and experimental results demonstrate that accounting for the edge effect is important for determining N leaching from urine-affected areas.

Cichota, R., Vogeler, I., Snow, V., Shepherd, M., Mcauliffe, R., Welten, B., 2018. Lateral spread affects nitrogen leaching from urine patches. Sci. Total Environ. 635: 1392–1404. doi:10.1016/j.scitotenv.2018.04.005

Monday, 30 April 2018/Author: Sarah Cleary/Number of views (230)/Comments (0)/
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