微塑料输入与秸秆添加对潮土和黄棕壤氮淋溶的影响

为探究微塑料输入与秸秆添加对农田土壤氮淋溶的影响，以潮土和黄棕壤为研究对象，每种土壤各设置8个处理，包括对照（CK）、低量微塑料（PE1）、中量微塑料（PE2）、高量微塑料（PE3）、秸秆（S）、秸秆+低量微塑料（S+PE1）、秸秆+中量微塑料（S+PE2）、秸秆+高量微塑料（S+PE3），研究了添加秸秆与不添加秸秆条件下，不同微塑料输入量对土壤氮淋溶的影响。结果表明，仅添加微塑料条件下，与对照（CK）相比，潮土PE1、PE2、PE3处理总氮（TN）淋溶量均无显著差异，黄棕壤仅PE1处理显著增加了TN淋溶量。在添加秸秆（S）处理中，与对照（CK）相比，潮土添加秸秆后显著降低了硝态氮（NO₃^--N）、铵态氮（NH₄⁺-N）、TN淋溶量，分别降低了31.15%、13.45%、15.26%，黄棕壤添加秸秆后显著增加了TN淋溶量，增加了22.56%。添加秸秆处理相较于不添加秸秆处理，潮土各浓度微塑料输入下NO₃^--N、NH₄⁺-N、TN的累计淋溶量呈降低趋势，而黄棕壤低量微塑料输入降低了TN淋溶量，高量微塑料输入增加了TN淋溶量。偏最小二乘路径模型（PLS-PM）分析表明，在潮土中添加秸秆主要通过影响淋溶液pH和NO₃^--N淋溶量影响氮素淋溶，微塑料添加量对氮淋溶无显著影响；在黄棕壤中添加秸秆主要通过影响淋溶液NO₃^--N、NH₄⁺-N淋溶量影响氮淋溶，微塑料添加量主要通过影响淋溶液NH₄⁺-N淋溶量影响氮淋溶。研究结果可为农田土壤微塑料污染风险的管控及减少土壤氮素的淋失提供依据。

Effects of microplastic input and straw addition on nitrogen leaching in fluvo-aquic soil and yellow-brown soil

This study aims to explore the effects of microplastic input and straw addition on soil nitrogen leaching in farmland. Fluvo-aquic soil and yellow-brown soil were taken as the research objects. Eight treatments were set for each soil, including control (CK), low microplastics (PE1), medium microplastics (PE2), high microplastics (PE3), straw (S), straw + low microplastics (S+PE1), straw + medium microplastics (S+PE2), and straw + high microplastics (S+PE3). A systematic investigation was made to clarify the effects of microplastic input on soil nitrogen leaching with/without the straw. The results showed that there was no significant difference in the TN leaching loss among PE1, PE2 and PE3 treatments in the fluvo-aquic soil with microplastics only, compared with the CK. In yellow-brown soil, PE1 treatment significantly increased the TN leaching loss. There was no significant difference in the TN leaching loss between PE2 and PE3 treatments. The addition of straw in the fluvo-aquic soil significantly reduced the leaching amount of NO₃^--N, NH₄⁺-N and TN, which decreased by 31.15 %, 13.45 % and 15.26 %, respectively, compared with the CK. The addition of straw in the yellow-brown soil significantly increased the leaching amount of TN, which increased by 22.56 %. Compared with no straw treatment, the cumulative leaching loss of NO₃^--N, NH₄⁺-N and TN under different concentrations of microplastic input in fluvo-aquic soil showed a decreasing trend, whereas, the low amount of microplastic input in the yellow-brown soil reduced the TN leaching loss, and the high amount of microplastic input increased the TN leaching loss. Partial least squares path model (PLS-PM) analysis showed that the addition of straw in the fluvo-aquic soil mainly affected nitrogen leaching via the pH of the leaching solution and NO3--N leaching loss, and the amount of added microplastics had no significant effect on nitrogen leaching. In the yellow-brown soil, the nitrogen leaching was affected by the leaching loss of NO₃^--N and NH₄⁺-N in the leaching solution. The microplastics mainly affected the nitrogen leaching for the leaching loss of NH₄⁺-N in the leaching solution. The research results can provide a sound basis for the control of the risk of microplastic pollution in farmland soil and the reduction of soil nitrogen leaching.