稻虾综合种养对稻田土壤肥力和金属元素含量的影响

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

  • 摘要: 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 > PRC > RM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。

     

    Abstract: The integrated rice-field aquaculture (IRFA) has been practiced successfully for 2000 years in China. The integrated rice-crayfish (Procambarus clarkii) co-culture (IRCC) has contributed more than 50% of the yield of IRFC, currently. Thus it is necessary to conduct researches on the IRCC, including its’ environmental impacts. As commercial feed feeding is very popular in IRCC practice, one of the potential environmental problems is the effects of feeding on the water and soil quality. Some previous studies have indicated that most nitrogen and phosphorus in the feed deposit in soil of crustacean aquaculture system. While it is not clear whether IRCC can increase nitrogen and phosphorus in soil, even some researches have been done. And it’s also not clear the effects of IRCC on the metal element contents in soil. The purpose of this study was to evaluate the impacts of IRCC in soil fertility (nitrogen, phosphorus and organic matter contents), and metal element contents on soil. Six physicochemical indicators and 11 metal elements contents of three layers of soil (0-10 cm, 10-20 cm and 20-30 cm) of the trench (TRC) and paddy (PRC) of IRCC, and rice monoculture fields (RM, as control) in Qianjiang City, Hubei Province, China, were measured, and the culture ages of the two modes were both 5 years. Contents of soil organic matter (SOM) and available phosphorus (AP) were measured by potassium dichromate heating oxidation-volumetrics, and NaHCO3 extraction, ammonium molybdate-tartaric emetic-ascrbic acid colorimetry method, respectively. Contents of total nitrogen (TN), ammonia nitrogen ( \rmNH_4^ + -N), nitrate ( \rmNO_3^ - -N) and total phosphorus (TP) were measured by flow injection analysis, and contents of Cr, Cu, Cd, Pb, Zn, Ni, As, Fe, Mg, Ca and Mn were measured by microwave digestion-inductively coupled plasma-mass spectrometry. The contents of Cr, Cd, Pb, Zn, Ni, As and Cu were then evaluated according to the risk screening values for soil contamination of agricultural land in <GB15618—2018>. The results showed that the TN, AP and TP content of all layers exhibited a trend of PRC > RM > TRC, while SOM (excepting 20-30 cm layer) and NH4+-N of RM > PRC > TRC and \rmNO_3^ - -N 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 significant differences were noted among TRC, PRC and RM for Cr, Zn or Ni, excepting for 0-10 cm longer. According to the risk screening values for soil contamination of agricultural land in <GB15618—2018>, Cr, Cd, Pb, Zn, Ni and As contents were up to 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 could increase nitrogen and phosphorus contents in the paddy soil, while decrease those in the trench soil, and SOM content.

     

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