Stephanie Murphy, Ph.D., Soil Testing Expert
Stephanie Murphy, Ph.D., is the director of the Rutgers Soil Testing Laboratory at Rutgers, the State University of New Jersey. She has 17 years of experience in soil science research, teaching, analysis and extension at Rutgers. She earned a B.S. in agronomy from Ohio State University, an M.S. in soil management and conservation from Purdue University and a Ph.D. in soil biophysics from Michigan State University.
Dr. Murphy started at Rutgers in soil microbiology research and then began teaching an introductory soil science course, which led to the opportunity to teach soil physics and continuing-professional-education short courses. She was asked to assist in the Rutgers soil testing lab, and upon retirement of another professor, she became director of the lab and soil testing became her primary responsibility.
Dr. Murphy offered her expertise to Tests.com and answered questions for us about soil testing.
Why is it important to conduct soil tests?
To determine the appropriate types and rates of fertilizer and/or limestone, it is necessary to understand the existing soil conditions. The correct balance of nutrients is not only important for the optimum growth/health/yield of the plants/crop but also for the health and sustainability of the environment. Many elements that are plant nutrients become water pollutants when applied incorrectly or at excessive rates. Soil pH is important because it affects the availability of nutrients, in addition to more direct effects of acidity or alkalinity. Other soil tests are used to evaluate soil quality, suitability for specific uses, or special management requirements.
Consumers may purchase an at-home soil testing kit, or they may contact a local soil testing laboratory to have an analysis performed. Which method do you most recommend? What are the advantages/disadvantages to both methods?
While do-it-yourself soil testing kits can provide a general sense of the soil condition, a laboratory soil test can provide more accurate and precise results and come with the added benefit of specific recommendations to provide nutrients and adjust soil pH for a consumer’s specific crops or ornamental plantings. While a do-it-yourself kit is inexpensive, many consumers would not know what to do with the resulting information. A soil test report from a laboratory not only includes precise values and ratings but also will provides the recommendations and is backed up with support from experts in the lab or in local Cooperative Extension offices.
What elements are necessary for soil fertility?
The elements that are generally recognized as essential plant nutrients include Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, Sulfur, Manganese, Copper, Iron, Zinc, Boron, Molybdenum and Chlorine. Additional elements (Cobalt, Vanadium, Silicon, Sodium) are cited in some cases or for specific plants. Plants obtain the first three listed here (C, H, O) from air (O2, CO2) and water (H2O). The rest come primarily from the soil.
What are the most important pieces of equipment and supplies that soil testing laboratories must have?
Equipment specific to a soil testing lab includes drying cabinets, grinders and sieves, gravity exhaust system and sand/soil traps for the sinks. Volumetric soil scoops are used to measure samples; also necessary are the chemical extractant(s) to solubilize plant-available nutrients and the pH buffers for determining the correct liming rate.
Standard laboratory instruments that a soil testing lab must have include electronic pH meters and an instrument for simultaneous accurate measurement of many nutrients in soil extracts, usually an inductively coupled plasma (ICP) spectrophotometer, though Rutgers uses direct current plasma (DCP) spectrophotometer. The more soil tests that are offered, the more equipment and supplies are needed.
What degree of education and training is necessary to do soil testing and who provides it?
The minimum education for soil testing laboratory technicians is a bachelor of science, preferably with a major in soil/plant sciences or earth/environmental sciences. In addition to having a good understanding of chemistry, it is important to understand the physical, biological and chemical processes occurring in the plant/soil relationship. In addition, hands-on experience is very valuable for converting information to practices “in the field.” Most colleges and universities offer degrees in earth and environmental sciences, along with chemistry requirements; land-grant universities - as well as certain smaller, specialized institutions - offer soil science and crop science majors.
Do you have any advice or suggestions for people who wish to get their soil tested?
Test your soil well in advance to make sure recommendations will be timely. Please read sampling instructions carefully before taking your soil samples. The sampling step must be done correctly for the analysis and recommendations to be useful. The soil sample should be representative of the area that is to be treated (limestone and/or fertilizer application). Do not sample an area that has been limed/fertilized recently; and wait (be patient!) for your soil test report/recommendations before making any applications.
Do you have any advice or suggestions for people who wish to get a job in the soil testing field?
A wide range of experience is helpful for relating to the wide range of situations that clients will present and ask about. Get a strong background in chemistry, plant science, and soils but also grow plants yourself and get involved with research if possible. Patience and perseverance is necessary since the laboratory routine of soil testing can become very monotonous. While cleanliness is generally important in chemistry laboratories, in this case you must tolerate some dust!
For more information on soil testing, please read our Soil Test Guide. If you're looking for a soil test, visit our Soil Test Directory.