作 者 ：党亚爱1;3;李世清1;2;王国栋3;邵明安1;2
期 刊 ：植物营养与肥料学报 2007年 13卷 5期 页码：831-837
Keywords:Loess Plateau, soil fixed ammonium, total nitrogen, physical clay,
摘 要 ：采集从北向南依次分布的干润砂质新成土(神木)、黄土正常新成土(延安)和土垫旱耕人为土(杨陵)等典型土壤剖面0—200.cm土层土样,通过测定土样全氮和矿物固定态铵,以阐明黄土高原典型区域土壤全氮和矿物固定态铵及二者比率随地理位置和土层的变异规律,为全面了解黄土高原土壤相对稳定氮库累积提供科学数据。结果表明,不同地理位置、不同土层全氮和矿物固定态铵含量存在显著差异。从南到北全氮和矿物固定态铵呈下降趋势,但各土壤全氮和矿物固定态铵的分布显著不同,全氮含量在0—60.cm随土层深度增加下降很明显,60—120.cm有一定下降,120.cm以下低而稳定。矿物固定态铵在全剖面上的分布比较均匀,随土层深度的变化差异不显著,不同土层间的差异基本在误差范围内,土垫旱耕人为土、黄土正常新成土和干润砂质新成土表层(0—10.cm)矿物固定态铵平均含量分别为215.80±7.45、165.80±8.73和146.50±1.83.mg/kg,表层以下(10—200.cm)平均含量分别为193.40±9.67、157.14±5.75和142.02±5.47.mg/kg。从地理位置分析,干润砂质新成土、黄土正常新成土和土垫旱耕人为土表层(0—10.cm)矿物固定态铵占全氮的百分比分别为(39.57±0.78)%、(32.91±6.82)%和(29.74±7.01)%;在表层以下所占比例更高,干润砂质新成土10—200.cm土壤矿物固定态铵含量占全氮比例为(89.52±13.42)%,黄土正常新成土为(59.52±13.86)%,土垫旱耕人为土为(47.26±9.01)%。供试土壤中矿物固定态铵与<0.01.mm物理性粘粒含量存在极显著正相关关系,说明物理性粘粒是矿物固定态铵的主要载体;矿物固定态铵与全氮含量也有极显著正向相关性。以上结果揭示,在黄土高原黄土母质上形成的土壤,全剖面矿物固定态铵相对均匀,而有机氮相差较大,两种氮库的这种地理位置和剖面分布特征,是黄土母质形成的必然结果,也进一步支持了黄土高原黄土母质的风成学说;同时也反映了需要对有机氮占全氮比例及矿物固定态铵在全氮中地位的传统观念予以重新评价。
Abstract:The total soil nitrogen,fixed ammonium and their relationship among the Ust-Sandiic Entisols(Shenmu),Los-Orthic-Entisol(Yan‘an) and Eum-Orthic Anthrosol(Yangling) on the Loess Plateau were investigated to assess the influences of soil location and depth(0-200 cm) on their contents and to accumulate first-hand data of soil nitrogen accumulation on the Loess Plateau.The results showed that the contents of total soil nitrogen and fixed ammonium differed significantly with location and soil depth.The contents of soil total nitrogen and fixed ammonium decreased significantly from south to north on the Loess Plateau,but their distributions differed significantly.In the same location,the content of total soil nitrogen decreased with soil depth remarkably within 0-60 cm,slightly within 60-120cm,and kept stable under 120 cm,whereas the content of soil fixed ammonium had no obvious change in the profiles.The average content of soil fixed ammonium was 215.80±7.45,165.80±8.73 and 146.50±1.83 mg/kg within 0-10 cm for EumOrthic Anthrosol,Los-Orthic-Entisol and Ust-Sandiic Entisols,respectively,and the averages of them for the three soils were 193.40±9.67,157.14±5.75 and 142.02±5.47 mg/kg within 10-200 cm,respectively.The average soil fixed ammonium nitrogen was(39.57±0.78)%,(32.91±6.82)% and(29.74±7.01)% of total nitrogen within 0-10 cm,and(89.52±13.42)%,(59.52±13.86)% and(47.26±9.01)% of total nitrogen within 10-200 cm of Ust-Sandiic Entisols,Los-Orthic-Entisol and Eum-Orthic Anthrosol,respectively.There was positive relationship between the contents of physical clays and soil fixed ammonium(P<0.01),indicating that physical clay was the primary carrier of soil fixed ammonium.There was also positive relationship between the content of soil organic nitrogen and fixed ammonium(P<0.01).The results showed that the content of soil fixed ammonium kept stable,whereas,soil total nitrogen differed with soil depth in the profiles at the same location.This characteristic was an inevitable result of Loess Plateau formation and supported the eolian theory of loess parent material.The results also indicated that the traditional understanding of the percentages of organic nitrogen in total nitrogen and the status of fixed ammonium in total nitrogen should be reevaluated.
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