Organic matter in the soil is an important substance for life activities and an important nutrient for plant growth**. It not only provides nutrients to plants, but also improves soil quality, increases soil water retention and air permeability, and promotes the reproduction and activity of microorganisms. Therefore, organic matter plays a vital role in the soil.
Organic matter refers to the collective term for organic compounds and organic matter in the soil. These organic compounds and organic matter** are found in plant residues, animal and microbial residues, and some organic fertilizers. They are constantly engaged in biochemical reactions such as decomposition, synthesis and transformation in the soil to provide nutrients and energy to plants.
The amount of organic matter in the soil varies depending on factors such as soil type, climate, vegetation, and soil age. In general, soils with higher organic matter content are darker in color and lighter in texture, while soils with lower organic matter content are lighter in color and heavier in texture. In addition, organic matter can also increase the water retention and air permeability of the soil, promote the reproduction and activity of microorganisms, and benefit the growth and development of plants.
Organic matter in the soil is an important nutrient for plant growth**, which plays an important role in improving soil quality, increasing soil water retention and air permeability, and promoting the reproduction and activity of microorganisms. In order to maintain and improve the organic matter content of the soil, reasonable farming, planting and management measures are required.
Acid-base titration can be used to detect organic matter in soil. Here's how to do it:
1. Preparation of reagents and equipment.
1.Reagent: 025mol l of sodium hydroxide solution, 001mol l of potassium dichromate standard solution, concentrated sulfuric acid (density of 184g ml), silver sulfate (powdered, active), porcelain evaporator, burette, volumetric flask, etc.
2.Equipment: electric hot plate or electric stove, water bath, burette clamp, etc.
2. Experimental procedures.
1.Sample preparation: Weigh 5g of soil sample, gently spread it in a porcelain evaporator of known quality, add 30ml of concentrated sulfuric acid, and shake to make the soil sample fully contact with sulfuric acid. Heating on an electric hot plate makes all the organic matter in the sample carbonized, and the solution is blue-green. Continue heating until white smoke of sulfur trioxide comes out, at which point the solution should be colorless or yellowish. Remove the evaporator, add 10ml of distilled water after cooling, and stir with a glass rod to soak the soil sample. After that, shake well every few minutes, and after all the ferric ions in the solution are reduced to divalent iron ions, add 10ml of potassium dichromate standard solution, and immediately use silver sulfate as a catalyst, with 025mol l of sodium hydroxide solution titrated to the endpoint. At the same time, a blank test is done.
2.Blank test: Add 10ml of distilled water to the porcelain evaporator, and the other steps are the same as the sample test.
3.Calculation of results: The content of soil organic matter was calculated based on the experimental data.
3. Precautions.
1.During the experiment, the influence of acid-base titration on the experimental results should be avoided.
2.In the heating process, the temperature should be appropriate to avoid the temperature being too high or too low to affect the experimental results.
3.During the titration process, the flow rate of the burette should be controlled to ensure the accuracy of the titration.
4.The reagents and equipment used in the experiment need to be stored and used in accordance with relevant regulations to ensure the accuracy of the experimental results.
5.After the experiment, the waste liquid should be properly disposed of to avoid affecting the environment and human health.