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通过田间原位试验,研究了连续8年免耕秸秆覆盖对土壤剖面NH_4~+-N、NO_3~--N和可溶性有机氮(EON)累积、垂直运移和淋溶损失的影响。试验设5个处理,分别为常规垄作对照(RT)、免耕无秸秆覆盖(NT-0)、免耕+33%秸秆覆盖(NT-33)、免耕+67%秸秆覆盖(NT-67)和免耕+100%秸秆覆盖(NT-100)。结果表明:免耕秸秆覆盖条件下,土壤可溶性氮素主要以NO_3~--N形态存在,其次是EON;免耕不同秸秆覆盖量对土壤NO_3~--N累积和垂直运移特性的影响不同;NT-33和NT-67处理中土壤NO_3~--N淋溶至40~80 cm土层,而NT-100处理淋溶至40~60 cm土层;与RT处理相比,NT-67和NT-100处理显著降低了0~20 cm土层NO_3~--N和EON库的容量,但增加了40~60 cm土层NO_3~--N库的容量;说明免耕秸秆覆盖增加了土壤NO_3~--N自耕层向深层的垂直运移和淋溶损失,但对EON和NH_4~+-N无显著影响。
The effects of no-tillage straw mulching on accumulation, vertical transport and leaching loss of NH_4 ~ + -N, NO_3 ~ - N and soluble organic nitrogen (EON) in soil profile were studied through in-situ field experiments. The experiment was divided into five treatments: conventional no-tillage (NT-0), no-tillage + 33% straw NT- ) And no tillage + 100% straw mulch (NT-100). The results showed that under no - tillage straw mulching, soil soluble nitrogen mainly existed in the form of NO_3 - N, followed by EON. The effects of no - tillage with different straw mulching on the accumulation and vertical migration of soil NO_3 ~ --N were different NT-33 and NT-67 leached to 40-80 cm soil layer, while NT-100 leached to 40-60 cm soil layer. Compared with RT treatment, NT-67 And NT-100 significantly reduced the NO_3 ~ --N and EON pools at 0 ~ 20 cm soil layer, but increased the NO_3 ~ --N pool capacity at 40 ~ 60 cm soil layer, indicating that no-tillage straw mulching increased Soil NO_3 ~ - N from vertical to deep vertical transport and leaching loss, but no significant effect on EON and NH_4 ~ + -N.