Integrated Aquaculture/Agriculture System (IAAS) Model Version 1.0

Transcription

1 Integrated Aquaculture/Agriculture System (IAAS) Model Version 1.0 Daniel Jamu, Raul H. Piedrahita, and Zhimin Lu Biological and Agricultural Engineering Department University of California One Shields Avenue Davis, CA 95616, U.S.A.

2 CONTENTS Page Acknowledgements 3 Disclaimer and Contact Information 3 1. Introduction 4 2. Getting Started 6 3. Model Inputs Aquaculture Inputs Agriculture Inputs 9 4. Model Simulation Model Outputs References 15

3 Acknowledgements The material presented in this manual is based on the senior author s Ph.D. research (Jamu, 1998). This research was supported by the Pond Dynamics/Aquaculture Collaborative Research Support Program (PD/A CRSP), under USAID Grant No. LAG-G and by contributions from the participating institutions, and by the Rockefeller Foundation through a Ph.D. fellowship awarded to the senior author. Appreciation is also due to the PD/A CRSP colleagues who collected the data used in this study. We wish to thank Drs. Kevin Hopkins, Doug Ernst, and John Bolte for their assistance with the PD/A CRSP database, and Dr. Shree Nath for the development of the fish growth model. We also wish to acknowledge the efforts of PD/A CRSP collaborators who were involved with field research for allowing us to share results of their experiments. The efforts of Dr. Randy Brummett, the ICLARM Malawi Office, and the Malawi Meteorological Department in providing pond input and meteorological data are also gratefully acknowledged Disclaimer The contents of this document do not necessarily represent an official position or policy of the University of California, the U.S. Agency for International Development, the PD/A CRSP, or the Rockefeller Foundation. Also, the mention of trade names or commercial products does not constitute endorsement or recommendation for use on the part of the above mentioned organizations. For additional copies of this manual or comments, please contact: Prof. Raul H. Piedrahita Biological and Agricultural Engineering University of California One Shields Avenue Davis, CA95616 Tel: rhpiedrahita@ucdavis.edu

4 1. Introduction The integration of aquaculture and agriculture systems is undertaken as a means of recycling aquaculture wastes (solids, organics and nutrients) that would otherwise be potential sources of pollutants to the environment. Integration also is used as a means of utilizing wastes produced from agriculture as feeds/fertilizers for aquaculture ponds. Nutrient losses from farm ecosystem are reduced through recycling, and this is highly beneficial in areas of the world where nutrient supply limits farm productivity and effluent discharge from aquaculture poses a danger of environmental pollution. Because of the low conversion efficiency of nutrients contained in feed and fertilizers to fish biomass (Edwards, 1993), unutilized nitrogen and organic matter accumulate in aquaculture ponds over time (Ayub et al., 1993; Tucker, 1985). The utilization of wastes from agricultural crops as fish feed/pond fertilizers, increased organic fertilization, and feeding of nutrient-rich diets can impact water quality, increase sediment nutrient accumulation and generally affect fish productivity. In such systems, the effects of water column and sediment nutrient/solids accumulation on water quality and the impacts of effluent discharge on the environment need to be adequately assessed. A key issue in this assessment is quantifying the role of pond sediments in overall water quality dynamics. Pond sediments are similarly important in relation to associated agricultural operations where they may play an important role in soil fertility for companion cropping systems. The need to improve existing pond water quality models so that they can be used to assess the impacts of water quality on pond production, effluent quality, and the environment led to the development of the integrated aquaculture/agriculture system (IAAS) model. The model, which builds upon existing pond ecosystem models (Piedrahita, 1984; Nath, 1996) and a general crop model (SUCROS1) (Spitters et al., 1989), simulates fish growth and crop production, organic matter, phytoplankton, dissolved oxygen, and nitrogen dynamics in an integrated aquaculture/agriculture system. In addition to the listed variables, the model also allows for the ecological analysis of the integrated aquaculture/agriculture system through the use of ecological indices. The model consists of the Aquaculture and Agriculture modules. The Aquaculture module consists of the Fish Pond Water Column and Fish Pond Sediment sub-modules while the Agriculture module consists of the Terrestrial Crop and Terrestrial Soil sub-modules (Figure 1). Each sub-module consists of sub-models for the different state variables.

5 Effluent Harvest Influent Feed Fish Pond Water Column Diffusion Fertilizer/Feed Sedimentation/ Resuspension Irrigation Terrestrial Crop Terrestrial Soil Nutrients and Water Fish Pond Sediment Sediment Fertilizer Fertilizer Infiltration Loss Figure 1: Conceptual diagram showing the different sub-modules, system input/output flows and boundaries for an integrated aquaculture/agriculture system.

6 2. Getting Started The IAAS model is written for the Stella modelling program, which is available for Windows and Macintosh operating systems. As such, the computer requirements are those needed for Stella ( The IAAS model is available by request. If the model is received on portable media (e.g. CD) it should be copied onto a hard disk for faster simulations. 1. Once the model file has been copied to the hard drive, click on the IAAS icon to open the file. 2. The model will open into the Stella higher level map. The high level map contains the different icons for changing parameter values, initial values, and graphical inputs for the different parameters.

7 3. Model Inputs Inputs for parameter values, initial values and time series data on weather and fertilizer input variables are handled through Stella slider input and graphic input devices as shown below in Figures 2 and 3: MeasSolarRadiation U? Figure 2: Stella graphical input device INITFishWt Figure 3: Stella slider input device 1. To open a graphical input device (GID) (Figure 2), double click on the desired input device. A graph and an output column are displayed when the GID is opened. The output column is situated to the right hand side of the graph. The initial and final days entered in the graph are the actual days of the year when simulation starts and ends 2. To edit the graph you can either use the cursor or input the values in the output column directly. To edit the graphical function directly, locate the cursor inside the graph, click and drag the cursor to effect the desired changes. As you drag the cursor, the values appear in the output column. You can also edit the graph by inputting values in the output column. If you have data in a spreadsheet file (e.g. Excel ), you can copy the data and paste it into the graph output column. The editing that is done to the graphical function is not necessarily permanent. When you OK the function relationship a restore button (U) will appear, and clicking the restore button will store the function relationship that existed before editing. 3. To select a slider input device (SID) (Figure 3), click within the slider border. 4. To change from the default value in the slider, type a number in the box that is situated in the middle of the slider, or move the slider until the desired parameter value is obtained. The value appears in the box that is situated in the middle of the slider. A switch with the symbol (~)

8 appears on the left hand side whenever the variable is associated with an equation or a graphical function. Whenever there is documentation associated with a variable, a question mark appears on the left hand of the SID (Figure 4). CropEmergenceDay U ? 68.7 Figure 4: Slider input device displaying the restore (U) and documentation (?) buttons If the edited value is greater than the maximum value displayed in the slider, the slider maximum value will be automatically retained. Only those slider input devices associated with model constants will display the restore button (U) instead of the (~) symbol. When changes are made to the model using the GID and/or the SID, the modified model should be saved as a new file. Hitting the restore button on the sliders or GID s for the modified parameters will revert to the default values. It is advisable to save model output as Excel files if further analysis is required. 3.1 AQUACULTURE MODULE INPUTS Graphical Inputs The IAAS model default values were calibrated using input data from a chicken manure experiment (1000 kg ha wk -1 ) conducted at El Carao, Honduras. To run the model using data from a different site, initial values, site characteristics, weather data and site-specific rate coefficients and parameters need to be changed. This is done through the use of graphical and slider input devices as reviewed above. The following management and weather parameters are inputted to the aquaculture module as graphical functions: Feed rate Fertilization rate Air temperature Feed rate (percent mean body mass per day). Inorganic and organic fertilization (kg.ha -1.d -1 or kg.ha -1.wk -1 ) Maximum and minimum air temperature ( o C). Solar radiation Measured solar radiation (J.m 2.d -1 ) Rainfall Daily rainfall (mm.d -1 ) Wind speed km. hr -1

9 Water temperature Average pond water temperature ( o C) Slider inputs Latitude Site elevation Latitude specified in degrees and minutes as a decimal. Negative for the southern hemisphere and positive for the northern hemisphere Site elevation (m above sea level) AGRICULTURE MODULE INPUTS Graphical inputs For the agriculture module, graphical input of data is required for the irrigation frequency and fertilizer application rate. Weather parameters also require graphical input as described in the aquaculture module inputs section above. Slider inputs Uses the same slider input values as described in the aquaculture module inputs section.

10 4. Model Simulation As stated earlier, the default IAAS model is calibrated using data from El Carao, Honduras. To run the model for a specific site, you need to: 1. Input the site-specific weather and management data as described in Section 3. A summary of the parameters that need to be defined in the aquaculture module before running the model are presented in Table Define the start and end day (Julian) of the simulation for all time series data inputted in a graphical function. Also, specify the fish stocking date and crop planting dates using the FishStocking and DayNumberonFirstDayofCropSimulation sliders. 3. To open the Graph Output and Tabular Output icons, double click inside the graph and tabular output icons. An empty graph or table will then be displayed. Table 1: Summary of model input data Variable Description Units Time interval - Elevation m constant - Latitude degrees constant I max Maximum light intensity mmoles.m -2.s -1 constant Chla Phytoplankton concentration mg Chla.L -1 initial value K sp Ks for phytoplankton by fish mg Chla.L -1 constant K N Ks for N uptake by phytoplankton kgn. ha -1 initial value W Individual fish mass g initial value CSC Critical standing stock kg. ha -1 constant g Fish genetic coefficient unitless constant P a Management allowable fish population fish. ha -1 constant P Fish population fish. ha -1 initial value O 2 Dissolved oxygen mgo 2.L -1 initial value k wc Water column respiration rate k d -1 constant k s Sediment respiration rate k d -1 constant ON Water column organic nitrogen mg.l -1 initial value TAN Water column TAN mg.l -1 initial value NO 3 Water column nitrate mg.l -1 initial value

11 - Water column organic matter kg.ha -1 initial value - Mineral sediment organic matter kg.ha -1 initial value - Mineral sediment nitrogen kg.ha -1 initial value T water temperature (min and max) o C daily - Air temperature (min and max) o C daily - Wind speed m.s -1 daily - Solar radiation J.m -2.d -1 daily - Water infiltration rate m.d -1 daily To specify the variables that you wish to display, double click inside the empty output graph or table (Figure 6). A dialog box showing allowable: on the left hand side and selected on the right hand side will appear. Scroll down the allowable list and double click on any variable or parameter to select it. Once selected, the variable or parameter will appear on the selected list Graph 1 (Untitled) Days 10:25 AM 9/17/98 Figure 6: Graph pad output page with no variables selected To deselect a variable, double click on the variable and it will move back to the allowable section

12 Once you have made the modifications that reflect the characteristics and management conditions for the new site, and selected the variables for the graphical and tabular output, you are now ready to run the model. RUNNING THE MODEL 1. Click the Run menu on the toolbar and scroll down to Time Specs. In the Time Specs dialog box, specify the length of the simulation in days by setting values for From to To corresponding to the initial and final Julian dates for the run. Leave other values unchanged and Click OK. Click on the Run menu again, and chose Run. 2 To stop the simulation before the simulation time is reached, click on Stop under the Run menu. 3. To pause the simulation, click Pause under the Run menu. In the pause mode you can inspect your results and change values for model constant using the slider input devices. To resume the simulation, click Resume under the Run menu.

13 5. Model Outputs Model outputs for the selected variables are displayed as a summary table, and as graphical and tabular output (Figure 7). Graphical or tabular output can be transferred to other applications for further analysis by highlighting the output and then copying the highlighted output into another application. MODEL OUTPUTS FishWeight FishBiomass StorageBiomass 1, ,951.9 Graph Output Table Output TotalSedimentDryWt 2,595.2 NitrogenRetentionIndex 1.8 TotalNOut TotalNIN NetDO 3.8 PercentSedimentN 0.1 PercentSedimentOrgMat 1.3 FeedQualityFactor 1.0 FishPopulation 8,503.1 SoilMineralN 78.5 FreshOrgMatterBiomass Figure 7. Sample Summary Table and Graph Output and Table Output icons. The outputs listed in the sample Summary Table (Figure 7) are: Fish Weight Fish Biomass Storage Biomass Total Sediment Nitrogen Retention Index Total N Out Individual fish mass (g) at the end of the specified simulation period Total fish biomass (kg ha -1 ) at the end of the specified simulation period Biomass of corn grain (kg ha -1 ) at the end of the specified simulation period Mass of unutilized organic matter (kg ha -1 ) at the end of the specified period Ratio of system nitrogen loss to nitrogen input Cumulative mass of nitrogen leaving the system (kg ha -1 ) by the end of the specified simulation period

14 Total N In Percent Sediment N Cumulative mass of nitrogen entering the system (kg ha -1 ) by the end of the specified simulation period N content of sediments (% of dry mass) at the end of the specified period Percent Sediment Org Organic Matter content of sediments (% of dry mass) Matter at the end of the specified period Feed Quality Factor Fish Population Soil Mineral N Dimensionless paramater (0-1) indicating the relative quality of a feed Number of fish (fish ha -1 ) at the end of the specified period Inorganic N content of soil (% of dry mass) at the end of the specified period Fresh Organic Matter Fresh organic matter in soil (kg dry weight ha -1 ) Biomass The Summary Table, just like the Graph and Table outputs, can be customized to fit the objectives of the simulation. To customize the Summary Table, double click on the table to get a dialog window that allows you to add or remove variables to the table. Printing To print graph or table output, double click on the graph or table icon, then select Print under the "File" menu. Alternatively, when a graph or table pad is opened, a printer icon appears on the left bottom corner of the pad. Double click on the printer icon to open the print dialog box.

15 References Ayub, M., C. E. Boyd, and D. Teichert-Coddington Effects of urea application, aeration and drying on total carbon concentrations in pond bottom soils. Progressive Fish Culturist 55: Edwards, P Environmental issues in integrated agriculture-aquaculture and wastewater-fed fish culture systems. In: R. S. V. Pullin, H. Rosenthal and J. L. Mclean (editors). Environment and aquaculture in developing countries. ICLARM Conf. Proc.31, 359p. Jamu, D. M Modeling organic matter dynamics in integrated aquaculture-agriculture systems. Effects of cycling pathways on nitrogen retention and system productivity. Ph.D. Dissertation, University of California, Davis. 297p. Nath, S., Development of a Decision Support System for Pond Aquaculture. Ph.D. Dissertation, Oregon State University, Corvallis. 273pp. Piedrahita, R. H Development of a computer model of the aquaculture pond ecosystem. Univeristy of California, Davis. Ph.D. Thesis. Spitters, C. J. T., H. van Keulen and D. W. G van Kraalingen A simple and universal crop growth model SUCROS1, p In R. Rabbinge, S. A. Ward, and H. H. van Laar (editors), Simulation and systems management in crop protection. Simulation Monographs, Pudoc, Wageningen Tucker, C. S Organic matter, nitrogen and phosphorus content of sediments from channel catfish, Ictalurus punctatus, ponds. Research Report 10. Mississippi Agriculture and Forestry Experiment Station, Mississippi State University, Mississippi State, Miss.