Manual for Tillage Translocation and Tillage Erosion Models
Department of Soil Science, University of Manitoba, Canada
Using an exponential model to describe tillage induced soil translocation, thereby to simulate tillage erosion as well as the redistribution of those materials moving along with soil, such as organic carbon, nutrients, and pesticides, Cs-137 etc.
Using grid elevation data (DEM) to calculate the on site tillage erosion rate at every grid point.
An Agri-environmental indicator developed in Canada used to indicate the risk level of tillage erosion. This model is still under-developing.
Fig 1. Open the program Fig 2. Chose model
Use the setup.exe file in the package to install the program. After the installation, the program menu will be listed in your start menu (Fig 1).
The installation procedure does not carry the sample files and help files with it, therefore the user must copy the support files manually into the hard driver. More specifically, the help files, “help.html” and the “help_files” directory, must be copied into the directory where the program was installed; otherwise the “help” or “F1” function in the program won’t work properly.
3. TILLAGE TRANSLOCATION MODEL-----TTM
· style="mso-spacerun: yes"> (3.3)
α------- average distance of tillage translocation on the level land (m)
β------- additional tillage translocation due to slope gradient (m/%)
θ------- slope gradient (%)
γ------- additional tillage translocation due to slope curvature (m2/%)
φ------- slope curvature (%/m)
The values of α, β and γ could be calibrated by tillage erosion experiments in the field (Li et al. 2002). They are mainly determined by implements type. Tillage speed, depth, soil properties also have strong effect on them (Lobb et al. 1999).
3.2.3. Calculation procedure
Considering a 0.1m (the data points interval) wide section on the slope. After tillage operation, soil within the tilled layer of this section will be distributed along the tillage direction to the downside sections. The amount of soil that has been moved into a certain section was determined by the distribution curve as showed in Fig 1 (equation 2.2) and the shape of the curve was determined by λ, which in turn was determined by the slope gradient and slope curvature of the section under considered (equation 2.3). For a certain section, it will receive soil from sections up to 5m in front of it and it will also output soil to the downside sections up to 5m away. The elevation change of that section was then the summation of input soil minus the summation of output soil. The calculation of organic carbon distribution is quite similar except for the concentration difference between different layers need to be taken into account.
3.3. Import data file
Preparation of the import data is the key step for this program. Once you get the data stored in a right format and order, the following steps are quite straightforward.
3.3.1. File format and sample files
The import data file contains the data on every data points and some critical parameters for the calculation. Four sample import data files have been provided. All of them are stored in “.TXT” format, and it is the only recognizable format for the TTM in this version. An Excel file, “TTM_Import.xls”, has also been provided. Users are strongly recommended to use the Excel file as a template and using “save as” in Excel to save your own data into “Text (Tab delimited) (*.txt)” file type.
The top five lines in the import data are parameters setting. In the sample file, they are set up as followed:
Sequence= 0 DataPoints: 900
DistributionDistance= 5 m Interval= 0.1 m
Lamda= 1 + 0.02 *SG+ 0 *SC
Tillage_Depth= 0.25 m
BD1= 1000 kg/m3 BD2= 1200 kg/m3 BD3= 1400 kg/m3
·tion of the first sequence (blue) and the last sequence (red), which were defined in the right side boxes. Light blue and yellow were used in both ends to indicate the generated artificial data for controlling the boundary effect.
·PADDING-BOTTOM: 0in; PADDING-TOP: 0.75pt; HEIGHT: 14.25pt"
An “Error Alarm” window will pomp up if the program find something wrong with the import data and the program will shut down by itself. If this happens, the user need to launch the program and redo everything from the very beginning again.
Fig 6. Grid Information Window Fig7. Set Delimiter Window
4.3.2. File format
The import data file could be in DAT, TXT or Excel format (Even though DBF shows up in the file type list, I’m not sure if I included it in the program or not. Anyway, if you do have the data in DBF format, you can try. If DBF doesn’t work, save it as one of the other three file types). The Excel format file is not preferred because it will take much more time for the computer to even read the data into memory.
4.3.3. Set delimiter:
If the import file is DAT or TXT file, the user need to tell the program what kind of delimiter was used in the import file to separate the numbers. For the provided sample DAT file, the delimiter is “Space” (Fig 7) while for the sample TXT file the delimiter is “Tab”. XLS file don’t need to set delimiter and will go directly to the next step but usually using XLS file is much slower.
Fig 8. Show Data Window Fig 9. TEPP Model Parameters Window
4.4. Output file
The results of TEPP can only be saved as a TXT file. This file can easily be imported into Excel or other spreadsheet software.
Fig 10. Save As Window Fig 11. TEPP Output File
In the output file, the first two parts show the date of the analysis, the grid information, model information and model parameters. The third part shows the model results, in which: