Soil structures consist of (3) soil particles, which range in various sizes. There is sand, which is the largest, then silt which is slightly smaller than sand, and finally there is clay, which are the smallest particles in soil. Here is an overview of the qualities of each particulates properties:
1. Sand: This large, hard fragment of rock (in perspective to soil structure) creates airspace in the soil, relating to good drainage, however the nutrient holding capacities of sand are very low.
2. Silt: Silt is a medium sized aggregate in soils, which comprise of organic materials with an adequate amount of both drainage and nutrient holding properties. Silt tends to be darker in color than sand or clay.
3. Clay: This is the smallest particle found in soils, and as a result, can hold onto nutrients and water well. This retains nutrients, however air and water can not easily or quickly move if this particle is dominant in the soils.
Unfortunately, most of the soil structure around the Twin Cities is clay based. Some structures are strictly clay, which presents drainage problems in poorly sloped development and recreation areas. There is a way to test your soil to give you an approximate assumption of what your properties soil consists of, which is called the Ribbon Test.
The Ribbon test is easy, take a small amount of soil and roll it in your hand. If you cannot form a ball of sorts, then the soil is extremely sandy and you will probably be able to visibly tell this from the start. Pinch the soil in between your fingers and move your fingers back and forth. This should result in a thin layer of soil being pushed out from your fingers. If the soil falls apart easily, you will have a silt based soil. If the soil holds together for about 1/2" before falling apart, you most likely have a good mixture of sand, silt and clay. If the soil holds together, then it is most likely clay-based.
The problems that are associated with clay soils pose a couple of problems to property owners. The largest one is probably drainage. 90% of the calls we get about drainage problems have clay soils on the property. There are ways to correct problem areas, including French drains, Drain Tile, and Dry Wells being the most common and cost effective ways of dealing with wet areas in the yard. The clay will not let water drain in a reasonable amount of time, so one, or a combination of these solutions should resolve the problem if installed correctly.
Another tell-tale sign of highly clay-based soils is tree roots that are visible in the yard. Now, this may be a combination of symptoms such as a clay-based soil, but it this problem may be enhanced by an irrigation system that is running too frequently and for short intervals. To achieve the healthiest and most resilient lawn, remember to set your irrigation settings for less frequent and longer run time intervals. This helps get water down deeper into the soil, which roots will reach for during the off days. If you have tree roots showing, you may want to call a professional company to assess the situation, because this could be a sign of a weak root system that won't hold well during strong winds and storms.