LUO Xu-qiang1,2, WANG Shi-jie2, ZHANG Gui-Ling3, DU XUE-lian2,4, WANG Cheng-yuan2, LIAO Jing-Jing1
(1. School of Geography and Tourism, Guizhou Normal College, Guiyang 550018, China; 2. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China; 3. College of Chemistry and Materials Engineering, Guiyang University, Guiyang 550005, China; 4. Department of Resources and Environment Management, Guizhou University of Finance and Economics, Guiyang 550004, China)
Abstract: To investigate the characteristics of nutrient contents in rhizosphere soil of plant and the adaptive mechanism of plant in the karst area, three types of pteridophytes including exclusive calciphytes, calcifuge and dispersed species were selected as the research objects, which have different adaptive abilities in the calcareous soil environment from the Maolan karst area. Rhizosphere soil and non-rhizosphere soil were collected by the spalling separation method and the N, P and K contents were measured, respectively. The results showed that: (1) The contents of total N in rhizosphere soil and non-rhizosphere soil were both high, in rhizosphere soil there is shown such an increasing order as to be exclusive calciphytes > dispersed species > calcifuges, and there is a significant difference between rhizosphere soils(p＜0.05), whether under different plant species or under different plant types. In non-rhizosphere soil, total N contents in calcareous soil are higher than in acidic soil. The contents of total P and organic P in calcareous soil are higher than in acidic soil (p＜0.05). In non-rhizosphere soil, the contents of total P in calcareous soil are at a higher level, but the available P is low, and it is extremely low in acidic soil. Either under various plant species or under various plant types, the variation characteristics of P contents are basically identical between in rhizosphere soil and in non-rhizosphere soil. The contents of total K in acidic soil are slightly higher than in calcareous soil both in rhizosphere and non-rhizosphere, but the available K in calcareous soil is significantly higher than in acidic soil (p < 0.05). The contents of available K in rhizosphere soil under various plant species are at the medium low level, but at a higher level under various plant types except the calcifuges. As for the contents of available K in non-rhizosphere soil, calcareous soil and acidic soil are both at high level. In addition, the contents of total K are at low level in all kinds of soils. (2) The rhizosphere effect of rhizosphere soil under exclusive calciphytes is stronger than under calcifuges in total N, P, K and organic P, available P, available K. Among them, the contents of total N, P, organic P and available P in rhizosphere soil are higher than in non-rhizosphere soil under exclusive calciphyte. Exclusive calciphytes and dispersed species have strong ability of activation to K and P. The activation ability of calcifuges to K and P is relatively weak, but the demand and the extent of absorption are higher. (3) The contents of each element and variation characteristics in rhizosphere soil and non-rhizosphere soil mainly depend on soil type, texture, water and heat condition, biological activity and so on. These results suggested that one reason for the growth restriction of calcifuges on calcareous soil may be their weak activation ability and the high demand for P and K.
Key words: karst; pteridophyte; rhizosphere soil; nutrient element
EARTH AND ENVIRONMENT Vol. 42, No.3, Tot No.299, 2014, Page 269-278
