【摘要】 本试验以三峡库区秭归县生态站所在流域内的柑橘园土壤作为研究对象,通过0～20、0～40、0～60 cm深度的原状土柱淋溶试验对不同施肥量对柑橘园土壤中氮素淋失及残留量的影响进行研究.试验中设置4种施肥处理,为不施肥处理（CK）、低氮施肥处理(T1:250 kg·hm^-2)、中氮施肥处理(T2:500 kg·hm^-2)、高氮施肥处理(T3:750 kg·hm^-2).结果表明:①柑橘园土壤中氮素淋失的主要形态为硝态氮（NO₃^--N）,占总氮（TN）淋失量的36. 93%～60. 07%,铵态氮（NH₄⁺-N）的比例为4. 40%～5. 79%.土壤中NO₃^--N残留量占TN残留量的比例为11. 31‰～45. 66‰,NH₄⁺-N残留量的比例为1. 05‰～2. 07‰;②相同深度的柑橘园土壤中,氮素的淋失量和残留量与施肥量呈显著正相关.不同施肥量下土壤中TN的淋失量和残留量分别为11. 35～30. 11 kg·hm^-2和0. 30～1. 86 g·kg^-1.其中,NO₃^--N和NH₄⁺-N的淋失量占TN淋失量的比例在T2处理下达到峰值,NO₃^--N和NH₄⁺-N的残留量占TN残留量比例峰值分别出现在T1和T2处理;③相同施肥量下,土壤中氮素不同形态的淋失量和残留量受土壤深度影响的差异较大.施肥后,NO₃^--N淋失量和残留量的峰值分别出现在20cm和40 cm深度,NH₄⁺-N淋失量和残留量的峰值主要出现在20 cm深度.从试验中的结果推论,0～40 cm土柱中的中氮处理更有利于肥料氮向无机态氮转化以供植物吸收并降低施肥后氮素淋失的风险.更多还原

【Abstract】 This experiment has the citrus orchard soil in the basin of the Zigui County Ecological Station in the Three Gorges Reservoir Area as its research object. Leaching tests of an undisturbed soil column at 0-20,0-40,and 0-60 cm depth were performed in a citrus orchard. The effects of nitrogen leaching and residual amounts in the soil were studied. Four kinds of fertilization treatments were set up in the experiment: no fertilization treatment（ CK）,low nitrogen fertilization treatment( T1: 250 kg·hm^-2),medium nitrogen fertilization treatment( T2: 500 kg·hm^-2),and high nitrogen fertilization treatment( T3: 750 kg·hm^-2). The results showed that:① The main form of nitrogen leaching in citrus orchard soil was nitrate nitrogen（ NO₃^--N）,accounting for 36. 93%-60. 07% of total nitrogen（ TN） leaching. The ratio of TN to ammonium nitrogen（ NH₄⁺-N） was 4. 40% to 5. 79%. The ratio of NO₃^--N residues in soil to TN residues was 11. 31‰-45. 66‰,and the ratio of NH₄⁺-N residues to TN residues was 1. 051‰-2. 07‰. ②Nitrogen leaching and residual amounts in citrus orchards at the same depth showed significant positive correlation with the amount of fertilizer applied. The leaching losses and residual amounts of TN in soil at different fertilization rates were 11. 35-30. 11 kg·hm^-2 and 0. 30-1. 86 g·kg^-1,respectively. Among them,the ratio of leaching losses of NO₃^--N and NH₄⁺-N to TN leaching amounts peaked under T2 treatment,and the peaks of NO₃^--N and NH₄⁺-N residues in TN residual amounts appeared in T1 and T2 treatment,respectively. ③ Given the same fertilization amounts,the leaching amounts and residual amounts of different forms of nitrogen in the soil were greatly affected by soil depth. After fertilization,the peaks of NO₃^--N leaching and residual amounts appeared at 20 cm and 40 cm,respectively,and the peaks of NH₄⁺-N leaching and residual amounts mainly appeared at 20 cm depth. Inferred from the results of the experiment,the neutral nitrogen treatment in the 0-40 cm soil column is more conducive to the conversion of fertilizer nitrogen to inorganic nitrogen for plant absorption,and reduces the risk of nitrogen leaching after fertilization.更多还原