模拟氮沉降下南方针叶林红壤的养分淋溶和酸化

以中国科学院红壤生态实验站林草生态试验区针叶林红壤为研究对象，在恒温(20 ℃)条件下，通过大土柱（直径10 cm、高60 cm），8个月间隙性淋溶试验模拟研究了不同氮输入量（0、7.8、26和52 mg N/月/柱）对针叶林红壤NO₃^-、NH₄⁺、H⁺和土壤盐基离子(Ca²⁺、Mg²⁺、K⁺、Na⁺⁾淋溶以及土壤酸化的影响.结果表明，土壤交换态盐基总量、Ca²⁺和Mg²⁺淋溶量随氮输入量的增加而增加，土壤交换态Na⁺和K⁺则无明显影响.4种N输入处理的土壤交换态盐基总量净淋溶（淋溶出的盐基与淋洗液累计输入的盐基之差）分别占土壤交换性盐基总量的13.9%、18.6%、31.8% 和57.9％，土壤交换态Ca²⁺净淋溶分别占土壤交换性Ca²⁺总量的19.6%、25.8%、45.3%和84.8%，土壤交换态Mg²⁺净淋溶分别占土壤交换性Mg²⁺总量的4.4%、6.1%、10.9%和17.1%.随氮输入量增加，表层土壤pH值逐渐下降，4种N输入处理的表层土壤pH（KCl）分别为3.85、3.84、3.80和3.75；随氮输入量增加，淋溶液中无机氮、NO₃^-和H⁺逐渐增加.氮沉降可促进针叶林红壤的有机氮矿化，加速养分淋失和土壤酸化.

Nutrient leaching and acidification of Southern China coniferous forest red soil under stimulated N deposition

In an eight months interval leaching experiment with soil column (10 cm in diameter and 60 cm in height) at 20 degrees C, this paper studied the effects of N deposition on the leaching losses of soil NO -, NH4+ , H+, Ca2+, Mg2+ , K+, and Na+ , and on soil acidification. Soil columns were taken from the coniferous forest experimental plot at the Red Soil Ecological Experiment Station of Chinese Academy of Sciences in Southern China, and the N deposition loads were 0, 7.8, 26 and 52 mg N x month (-1) x column (-1) , respectively. The results indicated that the leaching losses of total exchangeable cations, Ca2+ , and Mg2+ increased with increasing N deposition loads, but K+ and Na+ were little affected. The proportion of net cations leaching loss (difference of cations in eluate and leachate) to total exchangeable cations was 13.9% , 18.6% , 31.8% and 57.9% under 0, 7.8, 26 and 52 mg N x month (-1) column (-1) deposition loads, respectively, and that for exchangeable Ca2+ and Mg2+ was 19. 6%, 25.8% , 45. 3% and 84.8% , and 4.4% , 6.1% , 10. 9% and 17.1% , respectively. The leaching losses of inorganic N, NO3- and H+ also increased with increasing N deposition loads. Topsoil pH decreased with increasing N deposition loads, being 3.85, 3.84, 3.80 and 3.75 under 0, 7.8, 26 and 52 mg N x month (-1) x column(-1) N deposition loads, respectively. N deposition could increase the apparent mineralization rate of soil organic nitrogen, and accelerate the nutrient losses and acidification of coniferous forest red soil.