Web Soil Survey

As the foundation of any land-based ecosystem, soil is of paramount importance. The amount of nutrients and moisture in soil determines what and how many microbes, fungi, and plants will be present to help facilitate crucial processes such as decomposition and the carbon cycle, as well as the nitrogen and phosphorous cycles. A nutrient rich soil in an area with sufficient precipitation can support lush and diverse arrays of vegetation, such as a rain forest, which then in turn can support a variety of organisms up the food chain from insects, fish and birds to reptiles and mammals. Without soil, life in nature becomes much harder to survive. With this in mind, let's take a look at the USDA’s Web Soil Survey Website. 

The above screenshot shows the area I have selected, Saunders Woods Preserve, and I am impressed that it does have data for the different soil types even in a 25-acre area. The different letters stand for different classifications of soil based on composition. As we can see, Saunders actually has 6 different types of soil. Because Saunders is composed of a meadow near the top of a hill, then forest going down the hill to a stream, it makes sense that different types of soil would be present in the various terrains, slopes, elevations, and distance to water. 

 

This website may take a few minutes to get used to in terms of figuring out how to obtain the data you are looking for, but once you create your area of interest, you’re able to learn an incredible amount about the soil from the dozens of different filters you can apply. The filters are divided under two tabs: 1) Suitabilities and limitations for use and 2) Soil properties and data. While the former category consists mainly of different classifications for topics such as resources, disaster recovery, water and waste management, soil health, and more, the latter category details specific metrics and characteristics such as pH, calcium carbonate content, organic matter, clay/sand/silt percent, etc. I found a great number of these to be very interesting and will show some more screenshots to follow. There were only a few filters that were not applicable for this small of a scale, as was seen in the mapping exercise and post from a few weeks ago.

This filter shows the soil pH of the different soils in Saunders. While this is nothing groundbreaking, I do find it interesting to see. The data shows soils ranging from strongly acidic at a pH of 5.3 to neutral at a pH of 6.8. The presence of proximity of water understandably makes the soil less acidic. 

I found the organic matter filter interesting as well. It makes sense there would be some contrast between the forest area (blue) and the open meadow area (red). I believe we see higher organic matter levels in the forest due to more leaves, branches, and fallen trees decaying there to increase the level or organic matter in those soils.

This final screenshot shows the Conservation Tree and Shrub Group, which is a filter under the suitabilities and limitations for use tab. This filter shows classifications of soil and which trees and shrubs are best suited for them based on their physiological and climatic preferences. This could be very useful for trying to revegetate specific areas. There are 10 groups each with their own sub-categories. The description does not list what each of these categories mean though, rather I found that information as a PDF file on USDA’s website. We see ratings of 3 and 10 with this filter, and from the PDF these ratings mean the following about the trees and shrubs best suited for these soils: 

“Group 3 

Soils in this group are deep (at least 40 inches to a restrictive layer). The depth to a water table during the growing season is greater than five feet. Soils within this group are well drained, loamy textured soils with moderate and moderately slow permeability on uplands. These soils are well suited to all types of woody plantings. Except for those trees and shrubs that require abundant moisture, all climatically suited trees and shrubs have the potential to grow well. 

Competition from grass and weeds is the principal concern in establishing and managing trees and shrubs on these soils. Water erosion is a concern on the gently sloping to moderately steep areas.”

 

“Group 10 

Soils in this group have one or more characteristics such as soil depth, texture, drainage, channeled phases, available water capacity, slope or salts which severely limit planting, survival or growth of trees and shrubs. 

Soils in this group are usually not recommended for farmstead and feedlot windbreaks, field windbreaks, and plantings for recreation and wildlife. However, onsite investigations may reveal that tree and shrub plantings can be made with special treatments (hand planting, scalp planting, specialized site preparation, drainage, or other specialized treatments). The selection of species must be tailored to the soil conditions existing at each site. Limiting conditions and the specialized treatments required to overcome these limitations must be documented on the planting plan.” https://efotg.sc.egov.usda.gov/references/public/SD/ConservationTree-ShrubGroups.PDF

 

These were very informative classifications that would prove to be useful in a number of scenarios particularly in the field of ecology. Overall, The Web Soil Survey and its vast amount of data has proven to be a valuable resource for anyone who wants to understand more about soil in a given area. It was a good introduction for a beginner to soil science like myself, but has the depth to likely satiate seasoned experts in agriculture, geology, or ecology as well.