Downloading soils information

Revision as of 10:20, 2 August 2011 by Ed (Talk | contribs)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

If your area of interest is in the USA, you can use GeoAgro GIS to download soils information directly from the 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

Download Soils from the web soil survey

  1. Zoom in to your Area using the Zooming Tools.. Please note: It's convenient to keep the project area as small as possible, to make the soils download faster
  2. Select the “Soils” layer.
    Locate and pan over your planning area

  3. Click on the “WFS” tool to connect to the soil survey Locate and pan over your planning area
  4. In the Importing window, click on the star button to see which servers are available.Locate and pan over your planning area Now, select “NRCS Soils WGS84 Geographic”.
    Locate and pan over your planning area

  5. The “Layer” dropdown menu shows which layers in the service are available for download. Select “MapUnitPolyExtended”.
    Locate and pan over your planning area

  6. In "Unique values field", select "OBJECTID"
  7. 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.
  8. Your project should look like the screen below
    Click here to see it full size

Warning Warning: There is a current issue when downloading soils from USDA servers, which is that it donwloads soil map units from an area moved to the southwest from your current view. As a workaround, Pan the view moving it to the southwest.

Clipping your soils to a specific field

To clip soils map units to a specific field, please follow the steps described in this article.

The Copy Soil Survey tool Image:GIS_gis_Edit_22_01.jpg allows to generate a new polygon layer, by taking an existing layer and clipping it using a selected object of another layer as the clipping boundary.

For example, this tool is commonly used for creating soils map units within a field, based on downloaded soils features from the web soil survey


In order to work, it requires three elements:

1. An existing polygon layer (e.g.: downloaded soils map units)

You can use any polygon layer as the reference layer that will be clipped. In this example, we are going to use soil map units from the Web Soil Survey. Learn more about the Web Soil Survey >

To download soil map units from the USDA web soil survey for your farm area, you can use the Download WFS objects tool. After using this tool, you will have soil map units for your farm area


2. Select an object from a polygon layer that will be used as the clipping boundary (e.g.: a Field boundary) 

Also, before running the Copy Soil Survey Tool, you need to have an object selected, which will be used as the clipping boundary.

For instance, in the figure below,  Field 11 is selected. see Selection tools.


Note Note: If there is an object selected, the Copy Soil Survey Tool will be available. Otherwise, it will be disabled.

3. Run the Copy Soil survey tool

Click on the Edit objects panel Image:GIS_gis_Edit_05_01.jpg, and Select the tool Copy soil survey 'Image:GIS_gis_Edit_22_01.jpg, the following window wil pop up:


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).

Please make sure that you select the same data structure as the Soil Survey layer, in our example 'SsurgoSoils'


4. Calculate the attributes of the base layer:  clicking on this option will assing to the resulting polygons attributes from the 'Base layers'

As a result, a new layer with soils clipped in the selected field is created. In our example, it's F11_Soils