(+47) 922 65 448
Ås - Bygg H7
Høgskoleveien 7, 1433 Ås
I do my research on soil management and biogeochemistry, focusing on mechanisms for soil organic matter persistence. I have experience in agricultural and natural areas, especially in tropical climates (Brazil and southern Asia). My studies combine measurements at the nanoscale using spectromicroscopic techniques with bulk soil scale with a focus on organo-mineral associations.
Vitenskapelig – Microscale spatial distribution and soil organic matter persistence in top and subsoil
Thiago Inagaki, Angela R. Possinger, Steffen A. Schweizer, ...
ForfattereThiago Inagaki Angela R. Possinger Steffen A. Schweizer Carsten W. Mueller Carmen Hoeschen Michael J. Zachman Lena F. Kourkoutis Ingrid Kögel-Knabner Johannes Lehmann
The spatial distribution of organic substrates and microscale soil heterogeneity significantly influence organic matter (OM) persistence as constraints on OM accessibility to microorganisms. However, it is unclear how changes in OM spatial heterogeneity driven by factors such as soil depth affect the relative importance of substrate spatial distribution on OM persistence. This work evaluated the decomposition and persistence of 13C and 15N labeled water-extractable OM inputs over 50 days as either hotspot (i.e., pelleted in 1 – 2 mm-size pieces) or distributed (i.e., added as OM < 0.07 µm suspended in water) forms in topsoil (0-0.2 m) and subsoil (0.8-0.9 m) samples of an Andisol. We observed greater persistence of added C in the subsoil with distributed OM inputs relative to hotspot OM, indicated by a 17% reduction in cumulative mineralization of the added C and a 10% higher conversion to mineral-associated OM. A lower substrate availability potentially reduced mineralization due to OM dispersion throughout the soil. NanoSIMS (nanoscale secondary ion mass spectrometry) analysis identified organo-mineral associations on cross-sectioned aggregate interiors in the subsoil. On the other hand, in the topsoil, we did not observe significant differences in the persistence of OM, suggesting that the large amounts of particulate OM already present in the soil outweighed the influence of added OM spatial distribution. Here, we demonstrated under laboratory conditions that the spatial distribution of fresh OM input alone significantly affected the decomposition and persistence of OM inputs in the subsoil. On the other hand, spatial distribution seems to play a lower role in topsoils rich in particulate OM. The divergence in the influence of OM spatial distribution between the top and subsoil is likely driven by differences in soil mineralogy and OM composition.
Vitenskapelig – Susceptibility of new soil organic carbon to mineralization during dry-wet cycling in soils from contrasting ends of a precipitation gradient
Roland C. Wilhelm, Laurel Lynch, Tara M. Webster, ...
ForfattereRoland C. Wilhelm Laurel Lynch Tara M. Webster Steffen Schweizer Thiago Inagaki Malak M. Tfaily Ravi Kukkadapu Carmen Hoeschen Daniel H. Buckley Johannes Lehmann
The persistence of soil organic carbon (SOC) is influenced by soil physicochemical properties, organic matter quality, and climatic conditions that govern its vulnerability to microbial activity. We compared the susceptibility of newly formed SOC to mineralization in two soils (Andosols) that developed under contrasting precipitation regimes. Soil from the high rainfall region (‘highrain’) had higher SOC and lower iron concentrations than soils exposed to less rainfall (‘lowrain’). We amended soils with 13C-labeled carbohydrates and measured the amount of substrate-derived SO13C mineralized when exposed to dry-wet cycling following months-long incubations. We hypothesized that susceptibility would differ due to iron content and mineralogy, initial SOC, substrate solubility (cellulose versus glucose amendment), and microbial substrate use efficiency (SUE). We found that SO13C was less susceptible to dry-wet cycling when more 13C was assimilated into microbial biomass and co-localized with mineral surfaces than when co-localized with existing organo-mineral surfaces, according to microscale NanoSIMS imaging. Considerably less SO13C was susceptible to mineralization in the ferrihydrite-rich (low SOC) lowrain soil than the leached (high SOC) highrain soil when C was added as either glucose (7.3-fold less C mineralized) or cellulose (15.2-fold less). The SUE of glucose was comparable to cellulose in lowrain soil where SO13C was less water soluble and coprecipitated with ferrihydrite, and used half as efficiently as cellulose in highrain soil. Our results show that the susceptibility of newly formed SOC to mineralization is modified by the effects of bioavailability on microbial metabolism and the availability of mineral surfaces for forming new organo-mineral complexes.
Vitenskapelig – Andosol clay re-aggregation observed at the microscale during physical organic matter fractionation
Thiago Inagaki, Carsten W. Mueller, Johannes Lehmann, ...
ForfattereThiago Inagaki Carsten W. Mueller Johannes Lehmann Ingrid Kögel-Knabner
The high aggregate stability of Andosols and the direct effects of sample drying led to several inconsistencies during physical soil organic matter fractionation. We have determined that NaCl addition displayed little influence on clay dispersion. At the microscale, we observed the reaggregation of the clay fraction caused by freeze-drying. This issue was avoided by analyzing aliquots of soil suspension. Thus, we recommend reserving a small soil liquid aliquot to be subjected to microscopy analysis.
Vitenskapelig – Lime and gypsum application increases biological activity, carbon pools, and agronomic productivity in highly weathered soil
Thiago Inagaki, João Carlos de Moraes Sá, Eduardo Fávero Caires, ...
ForfattereThiago Inagaki João Carlos de Moraes Sá Eduardo Fávero Caires Daniel Ruiz Potma Gonçalves
Det er ikke registrert sammendrag