Error Analysis of Soil Moisture Sensor and Soil Moisture Monitoring

Error Analysis of Soil Moisture Sensor and Soil Moisture Monitoring
Soil moisture, also called soil moisture, is an important indicator for the study of agricultural drought and crop drought. Water is not only an essential material for plant photosynthesis to form carbohydrates, but also an indispensable constituent of the plant itself. Soil moisture is the main source of water absorption by plants, an indispensable medium for chemical, biological and physical processes in the soil, and an important factor in soil fertility. Therefore, it is of great significance for real-time service and theoretical research of agricultural production to conduct frequent soil moisture status determination and grasp the law of soil moisture change.

However, in the actual soil moisture monitoring, various errors will inevitably occur. In order to ensure the real-time, validity and accuracy of the automatic soil moisture monitoring observation data, and to make relevant personnel timely Avoid and adjust, and know what to do. This article will discuss the error and solution through two aspects of equipment and drying.

1. Soil moisture sensor

1. The selection of soil is not standardized

In addition to the equipment's own problems, the use of soil moisture sensors should also consider the large differences in geographical environment factors such as altitude, topography and soil texture. Area.

①There are differences in topography. There are many plots at the bottom of the ditch and slopes on the top of the mountain, and there are big differences in climatic conditions, planting systems, and irrigation conditions in a small area.

②The burial site contains more rocks in the soil layer, and more rocks and less soil make the soil volumetric water content naturally low and the soil relative humidity is also low, which greatly affects the actual measurement and causes data errors. happen.

③Some soil moisture sensors have less soil or uneven soil texture, which is similar to the impact of more rocks, and will directly affect the monitoring of soil volumetric water content.

④Improper installation method: There is a gap between the detection instrument and the soil, which will also cause a large error in the manual comparison of the observation data and the instrument observation data.

2. Solution:

Try to choose the soil that meets the requirements of the 'Automatic Soil Moisture Observation Specification

Strengthen the daily maintenance and management of soil moisture sensors. Many problems are mostly caused by improper installation, failure of the instrument itself, and inadequate maintenance and management. Therefore, the daily maintenance of observation instruments should be strengthened to find and solve problems in time. Ensure the normal operation of the soil moisture automatic monitoring system.

Second, drying method

1. Common problems of drying method

The drying method is a standard method for measuring soil moisture content. Dry the soil sample at 105°C to a constant weight. At this time, the soil organic matter will not be decomposed, and the free water and hygroscopic water in the soil will be driven away. The drying method is a method for measuring soil moisture in agrometeorological observatories. Compared with soil moisture sensor monitoring, the data is more accurate.

However, due to many factors such as land acquisition and human operation, there is a big difference between the same depth and different soil samples. Although increasing the number of samples within a certain plot area can reduce sampling errors, it will face the contradiction between sampling reliability and sampling workload. Therefore, analyzing the sampling error of soil moisture measurement by drying and weighing method is helpful to understand the stability of soil moisture data measured by agrometeorological observatory, and it can also provide a reference for the reasonable evaluation of the accuracy of soil moisture data.

2. Precautions:

1. The flat scale should be dried to constant weight first; the thickness of the test product should not exceed 5mm, and the loose test product should not exceed 10mm.

2. The test product should be weighed quickly and accurately, and the measurement error will be caused by moisture absorption due to excessively long time for weighing.

3. The temperature in the drying chamber of the ordinary oven is not uniform, and the weighing bottle should be placed under or around the mercury bulb on the upper layer of the thermometer.

4. During the drying process, unscrew the vent on the electric oven to allow water vapor to escape.

5. It is necessary to use an electric oven that has been verified by temperature distribution to ensure uniform temperature distribution in the drying room.

6. If the weight loss is more than 1%, 2 copies should be tested in parallel.

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