磷在原状土中的淋溶规律

研究磷在原状土中的淋溶规律及不同因素的影响。采用自行设计的原状土淋溶柱,探讨了磷在原状土中的淋溶规律。分别用pH值为4.0、6.8和9.0的淋溶液淋溶原状土,当淋溶液p H值由9.0降至6.8时,磷的总淋出量由2120.mg升至238.1 mg,增幅较小,p H值继续降至4.0,磷的总淋出量增加至271.9 mg;与未酸化的土壤相比,酸化后土壤中,磷的淋出量增加了22.18%,说明土壤酸化会增加磷的流失;以4 d为一个冻融周期,进行了不同冻融频次和冻前含水率的交替冻融试验。结果表明:在冻融频次小于5次时,磷的淋失量与冻融频次呈正相关,当冻融频次大于5次时,磷的淋出量随冻融频次的增加而减小;土壤冻前含水率越大,磷的淋失量也越大,冻前含水率由15%增加到25%时,淋失量由217.3 mg增长到316.2 mg,增长了45.50%。

Leaching Characteristics of Phosphorus in Undisturbed Soils

In this paper, the leaching rules of phosphorus in undisturbed soils and the effects of different factors on leaching were studied. Self-designed undisturbed soil leaching column was used to investigate the leaching characteristics of phosphorus. Undisturbed soils were leached by the leaching solution with pH values of 4.0, 6.8 and 9.0 respectively. When the pH value decreased from 9.0 to 6.8, the total leaching amount of phosphorus increased slightly from 212.0 mg to 238.1 mg. When the pH value continuously decreased to 4.0, the total leaching amount increased to be 271.9 mg. By comparison with the results from non-acidified soils, it was found that the leaching amount of phosphorus in the acidified soils increased by 22.18%, indicating that acidification of soils could increase the leaching of phosphorus. With 4 days as a freeze-thaw cycle, alternate freeze-thaw tests of soils were conducted at different frequency with different moisture content before soil freezing. The result showed that when the freeze-thaw frequency was less than 5 times, the leaching amount of phosphorus was positively correlated with the freeze-thaw frequency. When the freeze-thaw frequency was more than 5 times, the leaching amount of phosphorus decreased with the increase of the freeze-thaw frequency. The higher the moisture content was before soil freezing, the bigger the leaching amount of phosphorus was. When the moisture content before soil freezing increased from 15% to 25%, the leaching amount of phosphorus was significantly increased from 217.3 mg to 316.2 mg by 45.50%.