不同耕作方式对土壤有机磷形态的影响

Effects of different tillages on organic phosphorus fractions in soil

采用Bowman和Cole提出的有机磷分级体系，对陇中黄土高原0～5cm、5～10cm、10～30cm不同耕作方式下土壤有机磷的组成变化进行了研究．结果表明，陇中黄土高原有机磷的组成以中度活性有机磷占绝对优势，约占总有机磷含量的72．2％;其次为高稳性有机磷，占15．0％；中稳性有机磷占11．0％；最少的为活性有机磷，占总有机磷含量的1．8％．同一层次不同处理中，各形态有机磷均以免耕秸秆覆盖（NTS）含量最高，依次为：免耕秸秆覆盖（NTS）〉免耕不覆盖（NT）〉传统耕作结合秸秆还田（TS）〉传统耕作不覆盖（T）．土壤剖面中总有机磷和各组分有机磷含量变化规律为：表层总有机磷及表层各组分有机磷含基较高。随着深度的增加，总有机磷和各组分有机磷含量逐渐下降．同一层次不同处理的总有机磷含量均以免耕秸秆覆盖（NTS）最高，而传统耕作（T）在各个层次中总有机磷含量均最低.

Variation of soil organic phosphorus fractions and contents under different tillages for long term was studied in the layer of 0-5 cm, 5-10 cm,10-30 cm of calcareous soil in the Loess Plateau of central Gansu with the Bowman-Cole method. The results showed that moderately labile P occupied the most part of total P and accounted for 72.2%. In addition, highly resistant P,moderately resistant P and labile P accounted for 15.0%, 11.0 % and 1.8% of total P respectively. When different tillage systems were applied to the tested soil at the same layer, the contents of organic phosphorus fractions among treatments varied in the order of no-till with straw cover （NTS）〉no-till with no straw cover（NT）〉conventional tillage with straw incorporated（TS）S〉conventional tillage with no straw（T）. Both the contents of organic phosphorus fractions and the amount of total organic phosphorus tended to decrease with soil profile depth. The value of total P among treatments had the following characteristic. It is the most content of total P at the same layer for NTS among treatments,but the least for T.