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A Brief Guide to Improve Field Health by Soil Testing

1. What is Soil Testing?

Soil is a complex mixture of biological organisms, chemicals and physical components that must work together in order to transfer nutrients to the plants growing in its matrix. Not only is a balanced mixture of these elements vital for growing healthy crop yields, but the absence of inhibitors, toxins and pathogenic organisms that inhibit growth is also necessary.

Until recently farmers tried to determine what nutrients may be missing from their soil based on changes in color of their crops or growth of crops. Such methods were not scientifically based methods for how to test soil quality but were best guesses based on previous experience and knowledge passed down from elders or from books. Soil Testing replaces these experiential methods with scientific soil analysis to identify the presence of nutrients, pollutants, toxins and other soil components and give the farmer a complete understanding of the health of the soil.

2. Why is it important?

The growth processes of cultivated crop plants are intimately related to the health balance of nutrients in the soils in which they grow. Soils that have been depleted of minerals, have become salinated, or have high levels of toxins from years of pesticide/herbicide applications make plants susceptible to diseases and result in low crop yields. But guessing at what is needed to rejuvenate the nutritional balance of one’s soil can be costly. Adding minerals over hundreds or even thousands of acres is expensive, especially if it doesn’t actually fix the problem. Identifying the appropriate fertilizer to revive soil nutrients and the balance needed will save costs and will result in higher yields perhaps for years to come. These kinds of economic benefits make accurate soil testing methods all the more important.

3. Soil Testing Methods

Soil Testing can tell us a lot of different things about the soil. The most important of these things fall into these categories:

  • Fertility (agrochemical, physicochemical, physical, and biological parameters)
  • Contamination with pathogens (nematodes, fungi, bacteria, viruses)
  • Contamination (pesticide residues, heavy metals, radionuclides, organic contaminants)

When you look into how to test soil quality, the appropriate method will depend on the results expected. In other words, each analysis is done with the purpose of identifying certain parameters that have the potential to negatively, or positively, affect plant growth.

Mechanical Analysis 

Also known as particle size analysis, because it calculates the size of mechanical particles collected for soil analysis and groups their distribution by weight and diameter. This analysis reveals the amounts of clay and sand contained in the soil, and identifies the type of soil.

Chemical Analysis 

This identifies the content of various elements including how rich in nutrients the soil is. It will reveal the absorption capacity of the soil, if any heavy metals are present, how acidic the soil is, and whether fertilizer is needed. A variety of methods for chemical analysis are available including but not limited to; chromatographic, gravimetric and photometric. 

Chemical analysis reveals concentrations of heavy metals like; lead, cadmium, zinc, copper, nickel, arsenic, or mercury; as well as levels of benzo(a)pyrene and petroleum products in the soil. It can serve as a total pollution indicator that uses comparison data with maximum permissible concentrations (MPC) for each indicator. Conclusions can then be drawn based on the level of chemical pollution in the soil (clean, permissible, moderately dangerous, dangerous, extremely dangerous).

Agrochemical Analysis

This analysis determines the concentration of various chemicals in the soil affecting agricultural crops, garden plantings, or the health of farm animals.

Mineralogical Analysis

Offers data on the content of primary & secondary minerals in the soil which are vital for healthy plants and agricultural crops.

Toxicological Analysis

Detects the content of toxins in the soil including oil products, heavy metals and other toxins.

Microbiological Analysis

Reveals the number of microorganisms inhabiting the soil: bacteria, fungi, algaes, protozoa. Once their density per one gram of dry soil is determined, it is also possible to identify the presence of pathogenic microorganisms responsible for various plant diseases.

Soil pH Level

Determining the pH of the soil is one of the most important aspects of successful gardening and plant growth. Healthy plant growth depends on the proper synthesis of soil, water and nutrients within an ideal environment. A balanced soil pH allows for the harmonious development of plants, while poor pH levels lead to disease or even death.

4. How to Improve Field Health by Soil Testing

One of the simplest ways to improve the fertility of soil is to maintain an ideal pH level. Soil pH level is a major determinant for the ability of plants to absorb nutrients. In fact many of the agrochemical properties of soils that affect the processes by which plants grow and develop are maximized when the ideal pH is maintained. Even small changes in the optimal pH values whether up or down are detrimental to plant growth and productivity.

Therefore in order to improve agricultural field health and crop yield, farmers need to identify their soil pH and make the necessary adjustments to get their soil pH level to neutral. This process is known as deoxidation. Gardeners and farmers can add lime, chalk, ash, or dolomite flour to the soil to raise or lower the pH until it reaches neutral. Another option is for farmers to plant crops like alfalfa, oats, rye, or legumes and gardeners to plant phacelia or lupine. These plants are known as green manure plants and are good natural deoxidizers. By maintaining optimum soil pH farmers and gardeners will save on fertilizer use, while also increasing their farm and garden productivity.

5. Advantages of Soil Analysis

Because the quality of soil is so important for the quantity and quality of crop production, there are lots of advantages to regular soil testing. When the pH of your soil is known, it is relatively easy to know what kind of additive(s) as well as the amount of additive(s) needed to get to an optimal pH level. It is recommended that complete testing be completed immediately after harvest for best accuracy and that a control testing be done in the spring before planting.

By getting a complete testing after the harvest you can begin enriching the soil with the appropriate nutrients right away in preparation for sowing in the spring. And by having your soil tested before sowing your fields you can determine what vital nutrients are still low or missing and apply fertilizers that will maximize the fertility of your soil before planting.

It is not recommended that testing be done within two months after the application of fertilizers, pesticides or other chemical agents.

6. Conclusion

When you want to know how to test your soil quality you need a laboratory that understands soil analysis. When making your laboratory decision you should consider the professionalism, testing capabilities, experience of chemists, types of testing equipment and range of reagents. Your chosen laboratory should have the necessary capabilities for all soil testing methods. Examples include; microbiological, chemical and radiological analyses for all garden soil tests, pesticide and agrochemical tests for agricultural soil, soil toxicology tests for construction sites.

Torrent Laboratory gives you the highest certifications and most advanced capabilities.
Torrent offers advanced sampling, testing and reporting methodology for air, water and soil analysis. Our chemists perform all Volatile Organic Compounds (VOCs) analysis with next-generation Gas Chromatography and Mass Spectrometry systems. Our lab boasts the most highly-automated extraction capabilities in laboratory analysis for Semi-Volatile Organic Compounds in Northern California.

Torrent Laboratory’s environmental testing services are backed by a breadth and depth of certification, including California’s Environmental Laboratory Accreditation Program (CA ELAP), The Department of Defense Environmental Laboratory Accreditation Program (DoD ELAP), The Department of Energy Environmental Laboratory Accreditation Program (DoE ELAP) and the National Environmental Laboratory Accreditation Certification (NELAC). We offer testing services in all three matrices— Air, Water, and Soil—in all three disciplines of testing: Inorganic, Volatile and Semi-Organics, and Microbiology.