Norby R; Cabugao K; Yaffar D; Childs J; Stenson N; Phillips J
PR-EVR; PR-EVV; PR-Ica
El Verde Ridge; El Verde Valley; Icacos
Root data; Soil chemical composition; Soil properties - Other; Soil texture
Feb. 22, 2019
Feb. 25, 2019
With an objective of associating the distribution of roots in the soil profile with functional attributes related to phosphorus nutrition, 1-m cores were collected from sites in the Luquillo Experimental Forest, Puerto Rico, in February, 2019. The sampled sites were ridge and valley locations at El Verde and Icacos with soils that differ in parent material and phosphorus fertility. Depth profiles of soil physical characteristics (bulk density, moisture content, and particle size distribution), phosphorus content (total phosphorus, organic phosphorus, and resin or available phosphorus), soil and root-associated phosphatase activity, and fine-root traits (biomass, specific root length and area, and phosphorus content) were determined.
We measured fresh soil mass and then dried soil at 105°C for 2 days. We calculated bulk density as dry mass divided by core volume after correcting for removed material and calculated gravimetric water content (GWC) as fresh mass minus dry mass divided by dry mass. We determined soil particle size fractions (sand, silt, and clay) using the Bouyoucos hydrometer method on oven-dried and ground samples. We measured organic P as the sum of acid and alkali extractions. Samples were analyzed for total soil P using a Lachat BD40 block digester for high temperature digestion and a Lachat QuikChem 8000 series for flow injection analysis method. We manually picked roots from 0–5 cm, 5–7 cm, 12–15 cm, 20–25 cm, 30–45 cm, 50–80 cm, and 90–100 cm depths of each second 1 m core soil sample at all three locations and separated roots into two categories: ≤1 mm in diameter and >1 mm in diameter. We scanned fresh roots from each depth using WinRhizo to determine root length and surface area, and then oven dried and weighed them to determine specific root length and specific root area. Within 1 week of sampling, we measured soil and root phosphomonoesterase (PME) activities using a modified version of the colorimetric para-nitrophenyl phosphate (pNPP) assay.
Oak Ridge National Laboratory
U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research.
Norby, Rich - Oak Ridge National Laboratory ([email protected])
Norby R; Cabugao K; Yaffar D; Childs J; Stenson N; Phillips J (2021): Root-soil depth profile in Luquillo Experimental Forest, Puerto Rico, February, 2019. 1.0. NGEE Tropics Data Collection. (dataset). http://dx.doi.org/10.15486/ngt/1574087
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