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土壤氮素在降雨条件下淋失到深层土壤甚至进入地下水,不仅导致土壤肥力下降,同时还会造成地下水污染。本研究采用原状土柱室内模拟方法,通过模拟当地强降雨淋滤,研究了西双版纳州大渡岗普洱茶产区5年、20年、33年和56年茶园以及周边森林的0~20 cm和0~40 cm土壤层TN、NO_3~--N、NH_4~+-N和可溶性土壤有机氮(DON)的迁移变化,以及土壤p H变化对氮迁移的影响。结果表明:0~20 cm、0~40 cm土层的茶园土壤,TN迁移通量均随植茶年限的增加而增加(P<0.05),茶园年龄每延长一年,通过20 cm深的土层向下迁移下渗的TN通量将增加235.13 mg·m~(-2),而通过40 cm深的土层TN迁移通量则增加151.24 mg·m~(-2);0~40 cm土层的NO_3~--N迁移通量与茶园植茶年限显著正相关(P<0.05);0~20 cm土层的DON迁移通量与茶园植茶年限显著正相关(P<0.05);而NH_4~+-N迁移量不随植茶年龄变化而变化(P>0.05);茶园40 cm土层内的TN、DON和NH_4~+-N下渗迁移主要发生在0~20 cm,而NO_3~--N的迁移则主要发生在20~40 cm;40 cm土层的茶园土壤氮素以DON损失最多,其次为NO_3~--N,NH_4~+-N损失量最少;未发现茶园土壤p H对氮素迁移变化产生影响(P>0.05)。
Soil nitrogen leaching to deep soil and even into groundwater under rainfall conditions not only leads to the decline of soil fertility but also causes groundwater pollution. In this study, the original soil column simulation method was used to study the effects of local heavy rainfall leaching on the 0-20 cm and 0 0, 20, 33 and 56 years of tea plantations and their surrounding forests in the Pu’er tea producing area of Xishuangbanna. The changes of TN, NO_3 ~ --N, NH_4 ~ + -N and soluble organic carbon (DON) in ~ 40 cm soil layers and the effects of p H change on nitrogen migration were studied. The results showed that in the 0 ~ 20 cm and 0 ~ 40 cm soil layers, the fluxes of TN and MT increased with the increase of planting time (P <0.05). When the tea plantation age was extended by one year, The TN flux of infiltration under the downward migration will increase by 235.13 mg · m -2, while the migration flux of TN through 40 cm depth will increase by 151.24 mg · m -2 and 0-40 cm The migration flux of NO_3 ~ - N in soil layer was significantly and positively correlated with the tea plantation age (P <0.05). The DON flux in 0 ~ 20 cm soil layer was positively correlated with tea plantation age (P <0.05). However, the migration of NH_4 ~ + -N did not change with the age of tea plantation (P> 0.05). The infiltration of TN, DON and NH_4 ~ + -N in 40 cm soil layer of tea plantation occurred mainly in 0 ~ 20 cm, The migration of ~ - N occurred mainly in 20 ~ 40 cm. The losses of soil nitrogen in the 40 cm soil layer were dominated by DON, followed by NO_3 ~ - N and the least NH_4 ~ + -N loss. No tea plantation soil p H affected the migration of nitrogen (P> 0.05).