The Importance of Soil Testing
Soil is a complex system of chemical, biological, and physical process interactions. These interactions must be well balanced in order to grow and obtain high yields of cultivated plants.
Farming productivity and yields of crops greatly depend on the nutritional contents of the soil. Logical and well informed mineral nutrition is the basis for high yields. Farmers often visually determine the need for fertilizers. This method, of course, is not the most reliable as external signs can be confusing, and even an experienced specialist can easily be mistaken. The absence or excess of one of the necessary elements can block the flow for other vital elements.
When there is a lack of mineral nutrition in the soil, the cost of production is significantly increased, while the yield and profitability of the enterprise are reduced. Some types of plants are very sensitive to harsh weather conditions. If we add poor soil quality, poor absorption of mineral elements, salinity, and soil depletion to it, we may get an arsenal of diseases, the fight against which might not bring positive results. The best approach is to avoid, or at least minimize, the possible costs. For this purpose, soil analysis is carried out.
Methods of Soil Testing
Soil testing includes studies of the following characteristics:
- Fertility (agrochemical, physicochemical, physical, and biological parameters)
- Contamination with pathogens (nematodes, fungi, bacteria, viruses)
- Contamination (pesticide residues, heavy metals, radionuclides, organic contaminants)
The type of soil testing depends on the expected result. That is, each analysis is carried out in order to identify certain parameters that may negatively, or positively, affect plant growth.
- Mechanical analysis. This type of research is sometimes called particle size analysis, because it is based on the calculation of mechanical particles (granules) collected for soil analysis and their distribution into groups according to diameter and weight. As a result of the study, you will find out how much clay and sand the soil contains, as well as what type the soil belongs to.
- Chemical analysis of the soil. This test reflects the content of various elements and can show how rich the soil is in nutrients. It reveals the absorption capacity of the soil, the presence of heavy metals, the acidity level, and the need to use fertilizer(s). Methods can be different – photometric, chromatographic, gravimetric, among others.
The following data is received within the framework of a chemical analysis:
- Heavy metal concentrations: e.g. lead, cadmium, zinc, copper, nickel, arsenic, or mercury
- The content of benzpyrene and petroleum products
- pH level
- Total pollution indicator
Based on a chemical study and comparison of the data with maximum permissible concentrations (MPC) for each indicator, a conclusion is drawn on the degree of chemical pollution in the soil (clean, permissible, moderately dangerous, dangerous, extremely dangerous).
It serves to determine the level of concentration of various chemicals that can affect agricultural crops, garden plantings, or the status of farm animals health.
With its help, you can get data on the content of primary and secondary minerals in the soil, which make up the majority of the Earth (90–97%).
This soil test is used to detect the content of harmful substances in the soil such as arsenic, lead, mercury, oil products, etc.
This type of analysis is able to show the number of microorganisms that inhabit the soil: bacteria, fungi, algaes, protozoa. Having determined their density per one gram of dry soil, we can determine the biological activity and contents of the soil and the presence of pathogenic microorganisms that can cause various plant diseases.
Soil pH Level
Measuring the pH of the soil, water, and nutrient solutions for hydroponics is one of the most important aspects of successful gardening and plant growth. Healthy plant growth depends on the proper synthesis of the ideal environment. Balancing the pH of soil or water contributes to the harmonious development of plants, poor pH levels lead to disease or even death.
pH is the potential of hydrogen, which is determined by the quantitative ratio of H+ and OH- ions in water and reflects the degree of acidity or alkalinity of the environment. The pH scale ranges from 0 to 14. High pH levels indicate the soil is alkaline, while low pH levels indicate soil acidity. 7.0 is considered a neutral pH parameter.
The pH of the soil can often be defined by its color. Soil with a green tint is typically more alkaline, while soil of a yellow or orange tint is generally more acidic. However, color only gives us approximate pH values. More accurate soil pH can be measured with a pH meter, a device specifically designed for soil testing.
Ways to Change Soil pH Level
The pH level determines the degree of nutrient absorption by the plant. In fact, it is the pH that largely affects the agrochemical properties of soils, and therefore also influences the processes of growth and development of the plants grown there. Deviation from the optimal pH values in either direction is detrimental to plants. Of course, acidic soils will be more dangerous than alkaline. However, strong alkaline soils do not contribute to the normal development and productivity of most crops, either.
To achieve a rich yield, it is necessary to change the soil pH level to a neutral one. Farmers and gardeners call this process deoxidation. For this purpose, you can use lime, chalk, ash, or dolomite flour. Green manure plants also act as good deoxidizers. You can use lupine, alfalfa, phacelia, oats, rye, or legumes.
Maintaining optimum soil pH is not only about saving on fertilizer use, but also increasing the farm’s productivity.
Time and Frequency of Soil Testing
It is possible to carry out soil sampling at almost any time of the year since exhausted, dry, or frozen soils do not affect the final results of the analysis. In general, it is recommended to perform soil analyses shortly before the sowing process. In this case, you will be able to optimally apply the fertilizers that are necessary for your soil thus, obtaining higher yields. It is not recommended to take samples immediately after the application of fertilizers and other chemical procedures. Following such procedures, the tests may be carried out after a month or two.
How often should soil be tested? Chemical processes in the soil are ongoing. It is advisable to conduct agrochemical soil testing on all types of agricultural land annually. Moreover, complete testing is the most accurate after harvest with control testing in the spring.
Soil Testing Laboratories
In a competitive global industry, it is important to have accurate and specific data to ensure optimal conditions for growing crops while minimizing environmental impact and farming costs. The most objective assessment of the soil texture and fertility can be obtained only by regular professional testing. Soil testing procedures should be performed every 3-5 years to give a complete picture of soil fertility.
Choosing a laboratory for soil testing should be based on its equipment and range of reagents, as well as the availability of qualified specialists. The laboratory should have everything necessary for the analysis that you need. For example, chemical, radiological, and microbiological analyses are required for garden soil tests. Soil testing for agriculture requires pesticide and agrochemical analyses. Soil testing for construction should include toxicological soil reports.
You may order soil tests in a local laboratory as well as an international one. Nowadays, there are broad selections of facilities available. The only advantage of a local lab is that its’ experts have precise knowledge of local soils.
If you are in the US, you can quickly find a testing lab in each state.
European customers also have a large selection of labs dealing with soil testing.
Soil Testing with Crop Monitoring
Crop Monitoring offers an opportunity to determine the condition of the field with the help of “Zoning” The tool remotely identifies and highlights the problem areas. It allows making the soil testing in the needed areas only, thus significantly saving time and money on inspecting the entire field.