Pretreatment method for soil detection

The invention discloses a pretreatment method for soil detection in the field of soil detection, which comprises the following steps: soil pretreatment: pre-drying soil, pouring the soil along a feed opening of a pretreatment device, primarily crushing the soil by a crushing roller, grinding, preheating and heating the soil by a friction ball on a sieve plate, sieving the soil by passing through sieve pores, and transversely purging the soil by a fan at a constant air speed, a first container and a second container in the pretreatment device are used for collecting heavy metal-containing soil and common soil respectively; microwave digestion: the heavy metal-containing soil falls down along the long pipe end of the U-shaped pipe and is deposited at the bottom of the U-shaped pipe, an acid solution and a defoaming agent are sequentially added, the microwave emitter is started for microwave digestion, and a digestion solution is obtained; preparing constant-volume liquid: starting a suction pump to suck the dig