我国4种土壤磷素淋溶流失特征

磷素是水体富营养化的主要限制因子,地表水磷的污染负荷主要来源于农业面源污染。采集黑土、潮土、红壤和水稻土4种土壤,采用土柱模拟的试验方法,研究磷素在4种土壤剖面中空间分布特征,以及土壤渗漏液中TP、TDP的含量、动态变化以及流失量特征。结果表明:(1)不同类型土壤全磷和有效磷含量差异性显著,由高到低依次为水稻土潮土黑土红壤;黑土、红壤和水稻土土壤全磷和有效磷含量都表现出,随土壤深度的增加,不断降低;而潮土剖面呈上下层高,中间低的分布格局。(2)4种土壤渗漏液中占主导的磷形态不一致,潮土以MRP占主导,黑土和水稻土以DOP为主,而红壤则以PP为主。土壤磷素动态变化方面,潮土表现为TP含量先减后增再减,TDP含量先增后减;黑土表现为TP含量先增后减,TDP含量持续下降;红壤和水稻土TP和TDP含量变化不显著。(3)相关分析表明,4种土壤中Olsen-P与渗漏液中TP呈指数关系,具有极显著相关性。(4)4种土壤TP、TDP下渗流失量都以潮土最高,其次是黑土和水稻土,红壤流失量最小,磷素流失以TDP为主。

Characteristics of Phosphorus Leaching Losses in Four Soils in China

Phosphorus was the main limiting factor of eutrophication. Previous studies have shown that the pollution load of phosphorus in surface water mainly comes from agricultural non-point source pollution. This paper collected four main cultivated soils, i.e., black soil, fluvo-aquic soil, red soil and paddy soil, and a soil column simulation experiment was conducted to study the spatial distribution characteristics of phosphorus in four soil profiles, as well as TP, TDP contents, dynamics and loss characteristics of soil leakage. The results showed that: (1) The contents of total phosphorus and available phosphorus in different soils were significantly different: Paddy soil > fluvo-aquic soil > black soil > red soil. The contents of total phosphorus and available phosphorus in black soil, red soil and paddy soil all showed the decreasing trends with the increase of soil depth, but the profile of fluvo-aquic soil presented the distribution pattern that upper and lower lawyer was high, and middle was low. (2) The dominant forms of phosphorus in the four soils leakage were inconsistent. The fluvo-aquic soil was dominated by MRP, black soil and paddy soil were dominated by DOP, while red soil by PP. In terms of the dynamics of soil phosphorus, the contents of TP in fluvo-aquic soil decreased first and increased next, and then decreased, while the TDP content increased first and then decreased. Black soil showed that TP content increased first and then decreased, while continuous decline in TDP content. TP and TDP contents in red soil and paddy soil did not vary significantly. (3) The correlation between Olsen-P in soil and TP in leachate was analyzed. It was found that there was an exponential relationship between Olsen-P and TP in leachate in four soils. (4) The highest TP and TDP leaching loss was observed in fluvo-aquic soil, followed by the black soil and paddy soil, the smallest loss was in red soil. The largest proportion in phosphorus loss was TDP.