Author Topic: Introduction to Soil Testing  (Read 1853 times)

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Introduction to Soil Testing
« on: April 13, 2011, 11:10:34 AM »
Soil Testing

Chemical Analysis

Soil testing is the primary means of assessing soil quality and soil health. Most state universities have labs that perform soil testing for nutrient status. This service is available to the general public, as well as landscape professionals, for a nominal fee. The University of Massachusetts provides soil tests specifically for turf grass, and offers fact sheets on interpreting the results: Their cost for a soil test including organic matter is $13.00. See www.umass.edu/plsoils/soiltest/turfinterp1.htm for more information.

If a commercial lab is used, make sure they use the same chemical solution used by the state university lab, so that the results and fertilizer recommendations can be accurately compared. For example, UMass and Cornell use the Morgan solution (Sodium Acetate), and University of Vermont and University of Maine use the Modified-Morgan solution (Ammonium Acetate).

Commercial labs located outside of New England will use extracting solutions for their region. In Ohio and Southern Pennsylvania, the extracting solution is much stronger and overestimates plant-available nutrients in New England soils. For more information, consult with the lab manager at your local state university soil testing lab. The lab will return a sheet containing information on nutrients, pH, buffer pH, cation exchange capacity, percent base saturation and, if requested, heavy metals and organic matter percentage.  You should request organic matter percentage as this is an important factor in organic turf care. The standard state university methodology is called loss on ignition, which means a dry sample is weighed, incinerated and weighed again after all the organic matter is burned off.

Heavy metals, especially lead, should be requested if there is a suspicion that that the soil may be contaminated or it is coming from an unknown source.

Soil Sampling

A soil test can only be meaningful if the soil sample is representative. Soil samples should be taken from similar management regimes.  If there is an area of turf that is significantly different from other areas consider taking a separate sample from that area. The sampling depth should be between 4 and 6. Samples should be collected with a clean soil probe or spade. A stainless-steel sampling tube is a useful tool, especially if you are going to be sampling at least once a year. These tools run $50 to $150 and can be bought from horticultural supply companies. Five to 15 soil cores (depending on the size of the area being sampled) should be collected by zig-zagging across the area. The cores should be mixed in clean bowl and the blades of grass that might be in the sample removed. One to two cups of the mixture should be placed in a Ziploc bag and shipped to the soil lab.
« Last Edit: January 22, 2015, 11:49:29 AM by admin »