Pedosphere 31(6): 964--972, 2021
ISSN 1002-0160/CN 32-1315/P
©2021 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Short-term microbial responses to soluble inorganic P input in a tropical lowland rain forest in Amazonia
Yuri W. L. DE SOUSA1, Erika BUSCARDO1,2,3, Carlos A. N. QUESADA1, Henrique E. M. NASCIMENTO1, Laszlo NAGY1,4
1National Research Institute for Amazonia, Manaus 69067-375 (Brazil)
2Department of Forestry, University of Brasilia, Brasilia 70910-900 (Brazil)
3Centre for Functional Ecology, University of Coimbra, Coimbra 3000-456 (Portugal)
4Department of Animal Biology, University of Campinas, Campinas 13083-862 (Brazil)
      In non-flooded lowland rain forests with low soil phosphorus (P) in parts of Amazonia, P cycling largely occurs via leaf litter recycling by arbuscular mycorrhizal (AM) fungal symbionts. Occasional high input of P into these ecosystems occurs during drought years with increased litterfall. As the length and frequency of drought events are projected to increase in the region, a single-dose nutrient addition experiment was carried out to test how this would impact P cycling. An application rate of 4 kg P ha-1 was used, which corresponds to twice the amount of litter-derived P in an average year. It was hypothesized that i) the added mineral P would be immobilized by soil microorganisms, leading to measurable increase in soil microbial biomass carbon (C) and P and ii) AM colonization rate would be reduced by the pulse in mineral P available for plant uptake. The results did not support either of our hypotheses. The addition of P did not have an effect on AM root colonization, nor was P immobilized by soil microbiota during the experimental period. The lack of a difference between the control and treatment at our study site could be attributed to the relatively low one-off dose of P applied that did not change either the colonization rate of roots by AM fungi or the amount of soil available labile P. To obtain a mechanistic understanding of the availability, capture, and use of P by plant-symbiont associations in tropical rain forest ecosystems, further integrated studies of the soil-plant system combining long-term nutrient manipulations, modeling, and experimental approaches are required.
Key Words:  Amazon basin,arbuscular mycorrhizal fungi,nutrient addition,phosphorus cycling,soil microbial biomass
Citation: De Sousa Y W L, Buscardo E, Quesada C A N, Nascimento H E M, Nagy L. 2021. Short-term microbial responses to soluble inorganic P input in a tropical lowland rain forest in Amazonia. Pedosphere. 31(6): 964–972.
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