稻虾综合种养对稻田土壤肥力和金属元素含量的影响

为研究稻虾综合种养对稻田土壤肥力和金属元素含量的影响,对潜江市稻虾综合种养田(渔沟以TRC表示、田面以PRC表示)和水稻单作田(以RM表示,作为对照)土壤不同土层(0～10 cm、10～20 cm和20～30 cm)的主要肥力指标和金属元素含量进行了对比。结果显示,各土层总氮、速效磷和总磷含量均表现出PRC RM TRC的趋势,有机质(20～30 cm土层除外)、氨氮含量表现出RM PRC TRC的趋势,硝态氮含量表现出TRC PRC RM的趋势。各土层的Cu、As、Mg和Mn含量均表现出TRC PRCRM的趋势,而Cd、Pb、Fe和Ca含量的变化趋势与之相反;除0～10 cm土层外,Cr、Zn和Ni含量在TRC、PRC和RM之间均无显著差异。根据《GB 15618—2018》中的污染风险筛选值,各土层的Cr、Cd、Pb、Zn、Ni、As含量均未超标,而Cu含量普遍超标,超标率的范围为14%～46%。研究表明,稻虾综合种养可能会促进田面土壤中氮磷的积累、降低渔沟土壤氮磷的含量,也可能引起土壤中Cu、As、Mg、Mn的积累及Cd、Pb、Fe和Ca的减少。

Effects of integrated rice-crayfish co-culture on soil fertility and metal element content

Six physicochemical indicators and 11 metal element contents of three layers of soil (0~10, 10~20 and 20~30 cm) of the trench (TRC), paddy (PRC) of integrated rice-crayfish and rice monoculture fields (RM, as control) in Qianjiang City, Hubei Province, China, were measured to evaluate the effects of integrated rice-crayfish (Procambarus clarkii) co-culture on the physicochemical characteristics and metal element contents of the ricefield soil. The results showed that the total nitrogen, ammonia nitrogen and total phosphorus content of all layers exhibited a trend of PRC > RM > TRC, while organic matter of RM > PRC > TRC and nitrate of TRC > PRC > RM. The content of Cu, As, Mg and Mn of all soil layers showed a trend of TRC > PRC > RM, while Cd, Pb, Fe and Ca on the contrary, and less visible trend of Cr, Zn or Ni was noted. According to the second level of standard value of environment quality in , Cr, Cd, Pb, Zn, Ni and As contents were within the standard, while Cu content was generally out of the limits, with over-limit ratios of 14%~46%. The results indicate that integrated rice-crayfish co-culture increases nitrogen and phosphorus contents in the paddy soil, while deceases those in the trench soil; it increases Cu, As, Mg and Mn contents, while deceases Cd, Pb, Fe and Ca contents in soil.