黄土高原典型土壤有机氮矿化过程  

Organic N mineralization in typical soils of the Loess Plateau

作　　者：李紫燕[1,2] 李世清[1,2] 李生秀[2] 

机构地区：[1]西北农林科技大学/中国科学院水利部水土保持研究所黄土高原土壤侵蚀与旱地农业国家重点实验室,陕西杨陵712100 [2]西北农林科技大学资源与环境学院,陕西杨陵712100

出　　处：《生态学报》2008年第10期4940-4950,共11页Acta Ecologica Sinica

基　　金：国家自然科学基金资助项目(90502006)~~

摘　　要：以黄土高原从北向南不同地区典型土壤类为对象,采用Bremner淹水培养法,研究黄土高原典型土壤有机氮的矿化过程。结果表明,淹水培养期间矿化出的部分NH4+-N会被粘土矿物固定,固定量因土壤不同而异,因此在测定有机氮矿化量时,只有考虑这一部分氮素,才可获得可靠结果。不同土壤有机氮量矿化明显不同,表现为土垫旱耕人为土>黄土正常新成土>简育干润均腐土>干润砂质新成土,从南到北氮素矿化量呈减小趋势。添加C/N低(C/N比为21.7)的紫花苜蓿(Medicago stativa)茎叶有利于促进土壤有机氮矿化,而添加C/N高(C/N比为43.3)的长芒草(Stipa bungeana)会促进矿质氮的生物固定;不同类型植被土壤间在培养20、40d和60d时的矿化量差异显著(p值分别为0.0177、0.0109和0.0073),均表现为均为林地土壤>裸地土壤>草地土壤>农田土壤;从平均看,加(NH4)2SO4后有机氮矿化量有一定减少。在不同培养阶段,不同土类间氮素矿化率不同,在20d和40d时存在显著差异(p分别为0.0092和0.0381),60d时差异不显著,不同土类氮素矿化率的大小顺序为干润砂质新成土>黄土正常新成土>土垫旱耕人为土>简育干润均腐土,这一结果说明在淹水条件下,黄土高原土壤从南到北易矿化氮所占全氮比例呈增加趋势。The objective of this experiment was to improve our understanding of soil organic N mineralization in the Loess Plateau. Typical soils were sampled from north to south in the Loess Plateau and soil organic N mineralization was measured in the soils using the Bremner incubation method. The soils were incubated for 60 d. The results showed that part of NH4^＋ - N released during mineralization was fixed by clay minerals in these soils, so in order to get reliable results, we must consider this when determining total organic N mineralization. The amount of organic N mineralization was significantly different among the soil types. Specifically, the amount of mineralization decreased in the order Eum-Orthic Anthrosols 〉 Los-Orthic Entisols 〉 Hap-Ustic Isobumisols 〉 Ust-Sandiie Entisols. The amount of organic N mineralization decreased from south to north across the Loess Plateau. The addition of Medicago sativa residue, which has a low C： N ratio （C/N = 21.7）, increased the amount of organic N mineralization. In contrast, the addition of Stipa bungeana residue, which has a high C：N ratio （C/N =43.3）, increased microbial immobilization of soil mineral N. There were significant differences in the amount of organic N mineralization at 20d （p = 0.0117 ）, 40d （p = 0.0109）, and 60d （p = 0. 0073 ） depending on the type of vegetation growing on the soil at the time the samples were collected. The amount of organic N mineralization tended to decrease in the order： forest soil 〉 bare land soil 〉 grassland soil 〉 farmland soil. The addition of （NH4）2SO4 to the soil resulted in a decrease in the N mineralization rate at 20d （p = 0.0037） , 40d （p = 0. 0033 ） , and 60d （p = 0. 0027 ） compared to soils which did not receive （NH4 ）2SO4. There was a significant difference in the N mineralization rate among the different soil types when incubated for 20d （p = 0. 0092） and 40d （p = 0. 0381 ）, however, there was no significant difference in mineralization rates among the

关 键 词：黄土高原 土壤氮素矿化 非交换性铵态氮 

分 类 号：S153[农业科学—土壤学]