Downloading soils information
If your area of interest is in the USA, you can use GeoAgro GIS to download soils information directly from the USDA Web Soil Survey, using the WFS Tool.
WFS stands for Web Feature Service, and Open Standard that allows to retrieve geographic features from online servers - you may visit this WFS Article for more information.
Setup a sample project
For these exercises we are going to download a sample dataset: 'Sample Farm IA' and create a new project, or just open the project if you have previously created it.
For this purpose, you can follow the steps detailed in Download sample data, selecting 'Sample Farm IA' as the initial dataset, which can be found under the 'Tutorials_en' folder:
Download Soils from the web soil survey
- First, double-click on the 'Fields_NRCS' layer to zoom to the layer.
Please note: When downloading soils, it's convenient to keep the project area as small as possible, to make the soils download faster
- Select the “Soils” layer, under the Base Map group, to make it active:
- Click on the “WFS” tool to connect to the soil survey
- In the Importing window, click on the star button to see which servers are available. Now, select “NRCS Soils WGS84 Geographic”.
- The “Layer” dropdown menu shows which layers in the service are available for download. Select “MapUnitPolyExtended”.
- In "Unique values field", select "OBJECTID"
- Click on “OK” and wait for the download to complete.Please note: If the downloading bar does not show any progress, it might be due to the WFS server not responding. Cancel your download and try again.
- Your project should look like the screen below
Clipping your soils to a field
To clip soils map units to a specific field, we are going to use the Copy Soil Survey tool , which allows to generate a new polygon layer, by taking an existing soils layer and clipping it using a selected object of another layer as the clipping boundary.
This tool is commonly used for creating soils map units within a field, based on downloaded soils features from the web soil survey
To clip an existing soils survey layer to a field, you can follow these steps:
1. Select the field that will be used as the clipping boundary
Make the Fields_NRCS layer active by clicking on itSelection tools and select the field that will be used as the clipping boundary, as shown in the figure below:
|Note:||If there is an object selected, the Copy Soil Survey Tool will be available. Otherwise, it will be disabled.|
2. Run the Copy Soil survey tool
1. No. of Objects: shows the number of selected objects. In this example we have 1 field selected that will be used to clip the soil survey.
2. Soil survey: in this list, you need to select the layer in which the soil survey is located. In this example it's the 'Soils' layer.
3. Target Layer: Shows the layer where the resulting polygons will be saved. You can choose between an Existing layer or a New layer.
If you choose the New layer option, when you click on the Green Cross to create the New layer, the new layer window will pop up (learn more about Creating a Vector Layer).
Enter the following values:
* Name: F4_Soils (as a standard, we adopt for instance a prefix F4, to indicate layers specific to Field 4)
* Group: New Group -> 'Field 4'
* Structure: Make sure that you select the same data structure as the Soil Survey layer, in our example 'SsurgoSoils'
Click on Accept, as a result, a new layer with soils clipped in the selected field is created.
Use Selection tools -> Remove Selection, and turn off 'Soils' layer, to view only the Soils clipped in Field 4, as shown in the field below: