A close match between the actual soil type and the selected characterisation is essential for accurate Yield Prophet simulations. This means that picking the right soil characterisation is one of the most important steps in setting up your paddock, and pays dividends when you get it right. To make this job easier, we’ve implemented a new tool that will give you a shortlist of close matches to choose from, based on the results of a Particle Size Analysis (PSA).
PSA is available from most soil laboratories and can be ordered when you send in your soil samples for analysis. For use in Yield Prophet, a PSA should be ordered for each layer, which will provide you with a description of the soil texture in terms of % sand, silt, and clay. Entering these results into Yield Prophet is a simple process that is now included as an optional second step in Soil Setup:
1. Enter your soil test results into the first page of Soil Setup. At the bottom of the page, you will need to select whether the water values that you entered are close to CLL (Crop Lower Limit). If you are unsure whether this is the case, just select “Unsure”.
2. Clicking the continue button will take you to the “Enter PAWC values” page. If you don’t have a PSA, you can click “Skip this step” and continue to the soil selection page as usual. If you want to use the new soil selection tool and you have PSA results for your paddock, click the link on the right hand side to go to Soil Water Express. This is a CSIRO site that will estimate your soil water profile based on your PSA results.
3. Enter the details from your soil tests into the "Soil Characteristics" table of Soil Water Express. This includes the bottom depth of each layer, and the Sand (%) and Clay (%) figures. When you've finished entering your data, the "Estimated Soil Water Profile" table should update automatically - you may need to click on this title in order to see the table. Copy the values from the SW (mm) column in the Plant Available Water Capacity section, enter them into the table in Yield Prophet, and click “Continue”.
4. The “Select your Soil “ page will now display a shortlist of the 10 soils in the APSoil database that most closely match the details you entered. An estimated PAW (Plant Available Water) value will also appear in a box in the top right.
If you double click on the graph for any soil, a page will appear with more details on the characterization that can help guide your decision. One way that can help you quickly assess whether a soil might be appropriate or not is by comparing your PAW estimate to the PAW value given for the soil. An appropriate characterisation should have a similar PAW. Very different figures for PAW may indicate a suboptimal match.
If you decide that a soil in the shortlist is inappropriate, you can click the ‘Remove from list” button below the soil to hide it. Alternatively, if you decide you don’t want to use the shortlist at all, you can return to the old system by selecting the “Location” option from the “Select soils by” drop down box.
5. Once you’ve decided on a soil characterisation, click the “Select this soil” button below the soil details. The soil characterisation will be saved and you will be taken to a “Setup Paddock Soil” page that summarizes what you have entered. If you would like to change anything, including the soil characterisation, it can be easily done from this screen. Otherwise, click the “Save” button at the bottom of the screen to return to the paddock setup page. If you change your mind about the soil you’ve chosen, you can select a different characterisation for the paddock by repeating this process at any time.