Potassium nitrate commonly known as HuoXiao or soil denitration. It is black powder and important raw materials and compound fertilizers. Producing potassium nitrate can use denitration soil and plant ash as raw materials. Soil organic matter corruption, through the proposed bacteria and nitric acid bacteria role, generating nitric acid. Nitrate with soil of potassium, sodium, mg ions, forming nitrate. Such is the nitrate (soil. Denitration soil general exists in the toilet, pigs, kraal house, courtyard of old foundation, cliff edge, caves and not easily be rained ground. Denitration soil moisture, not easy to dry, classics sun blazed slightly change after purplish red. Good denitration soil on the charcoal burning red sparks will explode.