nstructions:   (1) First remove the soil layer about 5 cm deep on the surface of the soil to be tested, and clean up everything in the soil that will affect the test results.   Organic impurities of fruit, such as leaves, gravel and plant roots; if the soil at the measurement point is too dry or too fertilized   If the pH of the soil cannot be measured, it is necessary to splash water (preferably rainwater) on the measuring point and wait for 15-20   After the soil is soaked in minutes, the wet soil is measured (soil moisture 30%-60% measurement accuracy is the best),   Such as the measurement of the base soil, the effect is better.   (2) Before using the measuring instrument, in order to prevent the influence of the oxidation of the metal probe on the measured value. Abrasive cloth or   Wiping the metal probe with a clean cloth, or inserting and unplugging it several times in the soil can also remove the oxide film.   (3) When measuring pH and humidity, insert the metal probe of the instrument clockwise and vertically into the soil of the wet test point.   The soil is 6-8 cm in the soil, and the soil around the probe is evenly compacted. After the display is stable, the soil value can be read.   pH. If you press and hold the button on the side at this time, the value displayed by the instrument is the soil moisture value. dense soil   Degree, humidity and excessive fertilizer content may affect the measured value, so it is necessary to carry out several measurements in different locations to   Find the average.   (4) During the process of inserting the metal probe clockwise into the soil to be tested, if it is found that the position pointed by the pointer in the dial is not   Stable, this is due to uneven soil moisture or impurities and voids. Remeasurement is required to finalize the result.            Precautions:   (1) The time that the instrument metal probe is inserted into the soil should not be too long to avoid oxidation damage and damage to the surface of the probe.   surface, and after the measurement, the soil particles on the surface of the metal probe must be wiped off with a scouring pad in time.   (2) Make sure that the metal probe should be cleaned and kept dry before storing the instrument.   (3) The probe should be kept away from other metal substances;   (4) When the instrument is inserted into the soil: be sure to press down and insert the soil in a clockwise direction to measure, so that the soil and   Metal probes are in close contact. Remember not to turn the instrument back and forth to insert into the soil, otherwise, the gold   The probe is unscrewed and the connecting wire is broken and damaged, making it impossible to measure.   (5) The instrument is only used to measure wet soil. Too high or too low humidity will have obvious effects on the measurement of pH value accuracy.   Impact. It is recommended to measure soil moisture in the range of 30%-60%, pH is more accurate.                     Soil pH is also known as "soil reaction". It is the acid-base reaction of the soil solution. It mainly depends on the concentration of hydrogen ions in the soil solution, expressed as pH.