作 者 ：李勇1;张晴雯1;李璐1;万国江2;黄荣贵2;朴河春2
期 刊 ：植物营养与肥料学报 2005年 11卷 4期 页码：427-434
关键词：土壤营养元素；迁移强度；根系；有效根密度；黄土高原；
Keywords:nutritious elements, transport intensity, plant roots, effective root density, the Loess Plateau,
摘 要 ：不同植物群落根系对土壤元素迁移具有显著影响,不同基因型植物细根的特殊剖面分布特征,是其适应和改善土壤养分物理化学逆境的生理生态学基础。采用原状土柱淋滤实验装置及大型挖掘剖面壁法,在陕北黄土丘陵沟壑区研究并定量分析了不同径级根系对黄土中营养元素K、Na、Ca、Mg、Cu、Mn、Fe、Si、Al迁移强度的影响,旨在探索土壤养分生物有效性的提高途径。结果表明,不同植被类型土壤营养元素淋溶迁移的剖面差异并非完全取决于土壤中元素或矿物含量的大小,而是主要受制于直径≤1mm的须根根系在剖面中的缠绕分布特征。不同植被类型土壤中营养元素的迁移强度随土层深度增加呈递减规律。不同植物根系对黄土中营养元素迁移强度的影响具有显著差异,其大小顺序为:林地>草地>农地。林、草地土壤中元素迁移强度序列有明显变异的临界土层深度分别在30cm和10cm处。在林、草地和农地土层中常量元素水迁移强度序列为Ca>Na>Mg>K>Si>Al,微量元素基本为Cu>Mn>Fe。植物根系对营养元素迁移能力的影响具有明显的区域范围,随着直径≤1mm有效根密度和根量的增大,根系对土壤元素迁移强度的影响显著增强。
Abstract:Different plant roots may have potential impacts on nutritious elements movement in soil profiles. Distribution characteristics of fine root systems less than 1 mm in diameter in soil profile is the physiological basis of plants for adapting and improving adverse soil physical and chemical conditions. Few studies, however, have been conducted on the (nutritious) elements movement as affected by plant roots at profile scale. With the method of a large-size profile for (measuring) root density and an equipment of undisturbed monolith soil for measuring eluviation of elements, we investigated the transport intensity of nutritious elements, such as K, Na, Ca, Mg, Cu, Mn, Fe, Si, Al in the soil profiles as (affected) by root systems of different species of vegetation in hilly and gully regions of the Chinese Loess Plateau. The (objective) was to explore the approach to improve the biological effectiveness of soil nutrients. The results obtained (suggested) that transport differences among nutritious elements in soils were not depended on the amount of nutritious (elements) in soil rather than the distribution of plant roots of 1mm in diameters. The increased effects of roots on the nutritious (elements) movement in soil profile decreased as the soil depth increased. The effects of plant roots on nutritious element movement in soil profiles increased in the following order: forest land>grass land>farm land. The critical soil depth of different plant roots affecting elements transport in soil profiles was 30cm for forestry and 10cm for grassland. The movement of nutritious elements in soil profiles increased in the following order: Ca>Na>Mg>K>Si>Al for the normal elements, and Cu>Mn>Fe for micro-elements. The effects of plant roots on the nutritious elements movement in soil profile were weak when the effective root density of tree and grass were less than 17 and 60 roots per 100 cm~2 and root weight of tree and grass were less than 0.11 and 0.16 g per 100 cm~3 respectively. Plant roots can influence the nutritious elements movement in soil profile when the effective root density of tree and grass increased from 17 to 66 and from 60 to 106 roots per 100 cm~2 respectively, and root weight of tree and grass increased from 0.11 to 0.37 and from 0.16 to 0.30 g per 100 cm~3 respectively. Plant roots can significantly influence the nutritious elements movement in soil profile when the effective root density of tree and grass were more than 140 and 200 roots per 100 cm~2, and root weight of tree and grass were more than 0.70 and 0.40 g per 100 cm~3 respectively.
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