Skip to main content
ARS Home » Research » Publications at this Location » Publication #119232
Title: THE ROLE OF ARBUSCULAR MYCORRHIZAL FUNGI AND GLOMALIN IN AGGREGATION: COMPARING EFFECTS OF FIVE PLANT SPECIES

Author
item RILLIG, MATTHIAS - UNIV. OF MONTANA
item Wright, Sara
item EVINER, VALERIE - UNIV. CALIFORNIA-BERKELEY

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Sustainable agriculture depends upon good soil structure. Good structure promotes plant growth by controlling moisture, gases and nutrients. Also, a very important result of good soil structure is prevention of soil erosion by wind and water. The majority of our knowledge about the influence of soil microorganisms on soil structure is derived from experiments and observations on agriculturally important plants where farming practices ar a major influence. This study was done on naturally occurring plants to determine the influence of a ubiquitous group of soil fungi and a glue-like glycoprotein produced by hyphae of these fungi on soil aggregate stability. Aggregates are made up of soil minerals, plant parts, and microorganisms that adhere to each other. Stability of aggregates is a measure of soil structure. Hyphae are the fine hair-like projections produced by fungi to gather nutrients. Five plant species from a natural grassland were examined. There were significant differences in aggregate stability relate to different plant species. Statistical analysis showed that fungal hyphae and the glycoprotein produced on hyphae are important in determining the amount of water stable aggregates in soil. These results show the importance of one group of fungi on soil health and have worldwide impact on how to maintain or improve soil health.

Technical Abstract: Soil aggregation and soil structure are fundamental properties of natural and managed ecosystems. However, most of our knowledge on the role of plant species in soil aggregation is derived from work in agroecosystems or with agriculturally important plants. Here we examined the effects of five plant species on soil aggregate water stability. The five species (three grasses, ,one forb, and a legume) were from the same natural grassland, and were grown in monoculture plots in the field. Our first goal was to test if productivity-related or species-specific factors would prevail in determining soil aggregation. We also tested what the relative importance of the soil protein glomalin (produced by arbuscular mycorrhizal fungi, AMF) in soil aggregation is, compared to other factors, including AMF hyphal and root length and percent plant cover. We found significant differences in soil aggregate water stability for the five plant species examined, and corresponding differences in plant cover, root weight and length, AMF soil hyphal length, and glomalin concentrations. A structural equation modeling approach (path analysis) was used to distinguish direct from indirect effects of factors on soil aggregation based on covariance structures. Root length, soil glomalin, and percent cover contributed equally strong paths to water-stable aggregation. The direct effect of glomalin was much stronger than the direct effect of AMF hyphae themselves, suggesting that this protein is involved in a very important hypha-mediated mechanism of soil aggregate stabilization. We found no evidence to suggest that species-specific properties (such as association of a plant species with a particular AMF community) were important in determining the amount of water stable aggregates in the monoculture plots.