Effect of thermal radiation on soil phosphorus of protective farmland

Fire is an ecologically important character in many natural environments. To research the changes of various components of phosphorus under different thermal radiation temperature, choosing soil of protective farmland, by means of indoor thermal radiation simulation, soil was exposed under various high temperatures ranging from 100 °C to 700 °C, the results showed that thermal radiation had little effect on total phosphorus and available phosphorus significantly increased between 200–300 °C . As thermal radiation temperature was increased, water-soluble and loosely combined phosphorus content had a trend of first increase then decrease, reached the maximum at 300°C. Iron (Fe) P content and calcium (Ca) P content generally increased, aluminum (Al) P content and occluded (O) P content basically decreased. Under the radiation temperature between 100 °C and 400 °C, the soil organic phosphorus translated into inorganic phosphorus, Al-P and occluded P translated into water-soluble and loosely combined phosphorus and Ca-P. Under the radiation temperature between 400°C and 700°C, the Water-soluble and loose-bound phosphorus and Al-P translated into Fe-P, Ca-P and occluded P. Comprehensive analysis, 200–300°C was favorable when soil sterilization applied with thermal radiation.