Two Mistakes in Determining Soil Moisture

Soil moisture is one of the components of soil and has certain influence on the content of gas in the soil and the structure, physical structure and physical properties of the soil. It restricts the dissolution, transfer and absorption of soil nutrients and the activity of soil microorganisms, and has many influences on soil productivity. . Soil moisture has a great influence on the growth of plants. Measuring the law of soil moisture changes is conducive to the development of modern agricultural meteorological services, arid meteorological service and theoretical research. In the determination of soil moisture, some equipment must be used, such as wireless public opinion monitoring system for long-term monitoring of soil moisture changes, soil moisture analyzer for measuring timely soil moisture, soil drought and public opinion monitoring system, It is commonly used to detect drought and public opinion in China. The following are some of the susceptibility mistakes we have made in the determination of soil moisture from our soil monitoring stations in China.

(1) Some stations, after measuring the soil moisture content at each level, find that the weight water content at a certain level (referring to the average of 4 repetitions) is higher than the weight water content at the previous level. Large, no matter how much it is increased, it is believed that the weight water content of this level cannot be regarded as the field water holding capacity at this level, but it should continue to measure until the soil moisture content of the next layer is lower than the previous one. If the absolute value of the second difference is less than or equal to 2.0%, the soil moisture content at the next level is the field capacity at that level. All kinds of understanding are wrong. According to the specification, if the absolute value of the second-order difference between the soil moisture content of a certain layer before and after ≤ 2.0%, the weight moisture content of the first and second rounds will be high or low (due to the difference in measuring points, even if the soil weight is measured later). If the rate is greater than the previous time it is also normal, the soil moisture content of the next soil is taken as the field water holding capacity at that level, otherwise the field water holding capacity at this level will continue to be measured until the absolute value of the 2nd difference is ≤ 2.0%. The last measured value is the field capacity at this level.

(2) Some stations understand that when comparing the moisture content of two times before and after comparing a certain level, it is to compare each repetition of this level with the previous corresponding repetition. This understanding is also wrong. It should be a comparison of the two values ​​before and after the average value of the four repeated weight water contents at a certain level.