不同耕作方式对土壤有机磷形态的影响

采用Bowman和Cole提出的有机磷分级体系,对陇中黄土高原0~5 cm、5~10 cm、10~30 cm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量较高,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.

Effects of different tillages on organic phosphorus fractions in soil

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)>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.