How soil composition is tested and what soil testing mainly detects

Go to the agricultural technology extension station in your county. You can also go to your agricultural colleges and universities and ask the teachers of the Department of Agricultural Resources and Environment (formerly the Department of Soil Agrochemistry) of the College of Resources and Environmental Protection to help, they can give you a comprehensive soil test and guide you to improve, which may cost you.

Similar to the Environmental Protection Bureau, the Food Inspection Bureau, it should be fine. You can check the water you use for irrigation and rotate crops if necessary.

Soil testing items are divided into soil fertility index testing, soil pollutant testing, and soil other index testing.

Soil fertility index detection: organic matter, total nitrogen, total phosphorus, total potassium, nitrate nitrogen, ammonium nitrogen, available phosphorus, available potassium, slow-acting potassium, medium elements (calcium, magnesium, sulfur, silicon), trace elements (copper, iron, manganese, zinc, boron, molybdenum), etc.;

Soil pollutant detection: heavy metals (lead, arsenic, cadmium, chromium, mercury, nickel, cobalt, vanadium, thallium, antimony, beryllium), pesticide residues and other organic pollutants (organochlorine pesticides, organophosphorus pesticides, carbamate pesticides, polycyclic aromatic hydrocarbons, phenolic compounds, nitrobenzene compounds, aniline compounds, phthalic acid, etc.), etc.);

Detection of other soil indicators: pH, chloride ions, phosphates, water-soluble salts, cation exchange capacity, fluoride, etc.

1. Look at the color of the soil.

The color of the soil is an obvious indicator of the fertility of the soil and is the easiest method to master. Generally, the darker soil is loam, and the lighter soil is lean.

Second, look at the depth of the soil layer (tillage layer).

The fertile soil is relatively deep, usually more than 60 cm deep (except for paddy fields), while the barren and lean soil is very shallow, even less than 20 cm in severe areas, except for a layer of soil on the surface.

Third, look at the soil cultivability.

Generally, the soil is fertile in the field, the soil layer is loose, easy to cultivate, "dry tillage is like fragrant ash, wet tillage is like saccharification"; And in the fields with poor soil, the soil layer is clay and ploughed, and the cultivation is laborious, "knocking a hole, hoeing a crack".

Fourth, look at the slurry and cracks.

The fertile soil is not easy to deposit slurry, and the soil cracks are many and small; The lean soil is very easy to slurry, easy to compact, and the soil cracks are few and large.

Fifth, look at the water quality.

The water is slippery, sticky to the feet, and the sun or feet are blistering when they are blistered for the fertile soil; The water quality is light and colorless, and the paddy field does not bubble, or the bubbles are small and easy to disperse.

Sixth, look at water retention.

The water has infiltration, but the speed is gentle, and the irrigation can be maintained for about 1 week as fertile land; After irrigation, the water layer does not infiltrate or rapidly infiltrates along the cracks are lean soil.

7. See if it's a night tide.

Night tide refers to the phenomenon that the temperature of the topsoil decreases at night, and the warm water vapor in the deep soil rises, and when it encounters the low temperature topsoil, it condenses into water and moistens the topsoil. The night tide phenomenon can illustrate two advantages of soil: first, it is highly breathable, and warm water vapor can go up.

Second, the soil layer is deep, which can form a temperature difference. Therefore, the soil with night tide is basically loault; There is no night tide phenomenon, indicating that the soil is hardened and is lean soil.

8. Look at the fertility retention.

Soil is a negatively charged colloid, which can exchange and adsorb some cations (that is, nutrients) to achieve the role of fertilizer conservation, and these adsorbed nutrients will be gradually released from the soil during the growth of crops for crop absorption and utilization. Fertile soils are usually able to adsorb more cations, and the fertilizer effect is long-lasting. Poor soils usually have less cation adsorption, most of the nutrients are lost with water, and fertilizer efficiency comes and goes quickly.

1. Detection of pH value. First use distilled water to wet the soil, and then use pH test paper to test the soil acidity, the test paper is red is acidic, is blue is alkaline.

2. Moisture: The combustion weight loss method uses the high temperature generated by alcohol combustion to evaporate the water in the soil stove, and calculates the water in the soil through the water loss.

3. Organic matter: The color of the amount of trivalent chromium ions generated by diluting the organic matter in the soil by dilution of sulfuric acid-potassium dichromate and water is carried out colorimetric test.

4. Available nitrogen, phosphorus and potassium nutrients: After the combined extraction agent was used to extract the available nitrogen, phosphorus and potassium in the soil as excited, the nitrogen was determined by the indigol blue ratio pure sock color method, the phosphorus was used for molybdenum-antimony anti-colorimetry, and the potassium was determined by tetraphenyl boron potassium turbidimetry.

**The procedure for soil composition is as follows:

Experimental requirements: Soil composition.

Experimental instruments: water, soil, beakers, glass rods, alcohol lamps, evaporation dishes, matches, tripods, asbestos nets, glass sheets.

The experimental procedure is as follows:

1.Place a piece of soil in a cup of water. You will see bubbles coming out of the soil. Indicate that the soil contains (air).

2.Stir the water into the clods with a glass rod and let it stand. After precipitation, the substance in the cup is divided into three layers, the upper particle (smaller) and the lower particle (larger). Indicates that the material of the soil layer is (clay) and the material of the lower layer is sand grains.

3.Put the clods of soil into an evaporation dish and use an alcohol lamp to cover them with a thin glass to extinguish them, and after a while you will see (water droplets condensed) on the glass sheets. Indicate that the soil contains (water).

4.Remove the glass and continue to heat, you can see that the soil is whitish and smells burnt. Indicate that the soil contains (humus).

Soil refers to a layer of loose material on the surface of the earth, which is composed of various granular minerals, organic matter, water, air, microorganisms, etc., and can grow plants. Soil is composed of minerals weathered from rocks, organic matter produced by the decomposition of animal and plant and microbial residues, soil organisms (solid substances), water (liquid phase substances), air (gas phase substances), and oxidized humus.

Solid matter includes soil minerals, organic matter and nutrients obtained by microorganisms through light sterilization. Liquid matter mainly refers to soil moisture. Gases are the air present in the pores of the soil.

These three types of substances in the soil constitute a contradictory unity. They are interconnected, mutually restrictive, provide the necessary living conditions for crops, and are the material basis of soil fertility.

Hello, we are happy to answer for you, soil testing mainly includes chemical analysis, physical property testing, biological testing and microbial testing. Chemical analysis is to detect the content of soil components, including organic matter, inorganic water-soluble substances, etc. Physical pre-citrus detection is mainly to detect the apparent characteristics of the soil, including the color, shape, size, and abrasive structure of the sample.

Biological testing is mainly to detect the number and type of microorganisms in the soil, and the common methods include total number of colonies and strain detection. Weihui Li Tuan biological detection is mainly to detect the type and quantity of organic matter in the soil, and the common detection methods include gas chromatography, colorimetry, etc.

The soil detection method includes two parts: the pre-treatment and analysis of soil samples.

Pre-treatment of soil samples: The collected soil samples should be stopped from drying in time to avoid mold and cause changes in properties. The method is to break the soil sample into pieces and spread them on clean paper, spread them into thin layers and place them in a cool and ventilated place indoors to dry, and turn them frequently to accelerate the monotony.

Do not directly expose to sunlight, and the soil samples after air drying are stopped for grinding and screening.

Analysis and determination methods: atomic absorption spectrometry, spectrophotometry, atomic fluorescence photometry, gas chromatography, electrochemistry and chemical analysis, etc.

Soil environmental monitoring refers to important measures to understand the status of soil environmental quality. For the purpose of preventing and controlling the hazards of soil pollution, the dynamic analysis and determination of the degree and development trend of soil pollution. It includes the investigation of the current situation of soil environmental quality, the investigation of regional soil environmental background value, the investigation of soil pollution accidents and the dynamic observation of polluted soil.

Soil environmental monitoring generally includes steps such as preparation, distribution, sampling, sample preparation, analysis and testing, and evaluation. Quality Control Quality assurance should be done throughout.

The significance of soil testing

Soil environmental testing refers to the determination of soil quality by determining the environmental quality or pollution degree and its change trend through the determination of the representative values of the factors affecting the soil environmental quality. What we usually call soil testing refers to soil environmental testing. Generally, it includes the preparation of samples, distribution sampling, analysis methods, research results, statistics and quality evaluation of data.

Due to the development of industry, the problem of soil degradation has become more serious day by day, and the quantity and quality of land have declined, so the main purpose of soil testing is to test the quality standards of soil. The items that require measurement will use various instruments to determine whether the soil is contaminated, or to what extent. This is more conducive to us to grasp the quality of the soil, to carry out scientific planting, and balanced fertilization.

Conventional soil test items include: hydrolyzable nitrogen (alkaline hydrolyzable nitrogen), total nitrogen, total phosphorus, available phosphorus buried rock, total potassium, *potassium, *potassium, organic matter, pH, total sodium, available copper, total copper, available zinc, available iron, arsenic, total lead, total cadmium, total chromium, available boron, available silicon, bent early iron, manganese, copper, zinc, exchangeable calcium, magnesium, exchangeable sodium, total salt, humic acid, exchangeable manganese, etc.