Submitted to: International Neotyphodium Grass Interactions
Publication Type: Proceedings
Publication Acceptance Date: 5/24/2004
Publication Date: 5/24/2004
Citation: Franzluebbers, A.J., Hill, N.S., Jenkins, M., Zuberer, D.A., Humayoun, S.B., Stuedemann, J.A. 2004. How does soil respond to wildtype endophyte?. International Neotyphodium Grass Interactions. p.3
Interpretive Summary: Toxic effects of endophyte-infected tall fescue on grazing animals have been well documented. Pastures with high occurrence of endophyte-infected tall fescue have also been found with greater soil organic carbon and nitrogen concentration. Scientists at the USDA Agricultural Research Service in Watkinsville GA in collaboration with scientists at the University of Georgia and Texas A&M University conducted experiments to determine how soil organic matter might be altered in the presence of leaf tissue added to soil. Carbon forms of soil organic matter were negatively affected and nitrogen forms were positively affected by endophyte addition to soil. The chemical compounds in endophyte-infected tall fescue (ergot alkaloids) that are responsible for animal health disorders were found in soil, suggesting that these chemicals are persistent in the environment. Further tests are needed to determine whether these chemicals are responsible for increases in soil organic matter, which has implications on soil fertility and soil carbon sequestration.
Technical Abstract: Toxic effects of Neotyphodium-infected tall fescue on grazing animals have been well documented. Pastures with high occurrence of endophyte-infected tall fescue have also been found with greater soil organic carbon and nitrogen concentration. We hypothesized that either (1) greater tall fescue growth and/or (2) reduced soil microbial activity might be causing organic carbon to accumulate to a greater extent in soil under tall fescue with high endophyte infection. Soil organic carbon and total nitrogen in 20-year-old K-31 tall fescue pastures were greater with high endophyte infection (80%) than with low endophyte infection (40%), but only with high fertilization. Addition of endophyte-infected tall fescue leaves to soil resulted in lower soil microbial biomass carbon, but higher potential nitrogen mineralization than addition of endophyte-free leaves. Ergot alkaloid concentration in leaves declined logarithmically with time during decomposition with an initial increase with time detected in water extracts and a minor accumulation in soil sediment. Soil biochemical transformations are altered by endophyte infection of tall fescue.