Fungal translocation as a mechanism for soil nitrogen inputs to surface residue decomposition in a no-tillage agroecosystem
Abstract
Additions of (15NH4)2SO4 to the soil inorganic nitrogen (N) pool were used to measure rates of N flux from the mineral soil to surface-applied wheat straw decomposing in intact soil cores collected from a no-tillage (NT) field. Half of the soil cores were treated with a fungicide to reduce fungal populations. Fungicide application significantly reduced fungal biomass, decomposition rates, and net N immobilization in surface residues. Net N immobilization over the study period was estimated to be 1.5 and 0.9 g N m−2 for untreated and fungicide-treated residues, respectively. The rate of 15N transfer averaged 13.4 μg 15N g−1 residue d−1 for untreated wheat straw. Fungal inhibition reduced 15N flux by 59–78%, reductions of similar magnitude to those observed for fungal biomass. Nitrogen transfer in sterilized soil cores accounted for only 7.8% of the total upward N transport in control cores, indicating that abiotic processes did not contribute substantially to N flux. We estimate a total annual fungal-mediated N flux of 2.4 g m−2, which is nearly equivalent to the N immobilization potential predicted, based on initial N and lignin content, for the wheat straw used in this study. We conclude that fungal N translocation is a significant mechanism for soil N input and can account for the observed net N immobilized by surface residues decomposing in the field. Both residue quality and N availability appear to be important controls on fungal biomass associated with surface residues and rates of soil-to-residue N translocation.
Department
Soil Biogeochemistry and Microbial Ecology
Publication Date
3-21-2000
Journal Title
Soil Biology and Biochemistry
Publisher
Elsevier
Digital Object Identifier (DOI)
Document Type
Article
Recommended Citation
S.D. Frey, E.T. Elliott, K. Paustian, G.A. Peterson, Fungal translocation as a mechanism for soil nitrogen inputs to surface residue decomposition in a no-tillage agroecosystem, Soil Biology and Biochemistry, Volume 32, Issue 5, 2000, Pages 689-698, ISSN 0038-0717, https://doi.org/10.1016/S0038-0717(99)00205-9.
Rights
© 2000 Elsevier Science Ltd. All rights reserved.