DOI: 10.48443/skt2-5w34
title: Soil physical and chemical properties, periodic (DP1.10086.001)
title: RELEASE-2026

description: This data product contains the quality-controlled, native sampling resolution data from NEON's periodic soil sampling, as well as measurements of pH, moisture, chemistry, and stable isotopes. Samples collected as part of this product are also used for microbial measurements; those data can be found in associated data products.

Soil is defined as the upper layer of the earth's surface where plants grow and consists of decomposing organic material and inorganic particles such as clay and rock. Soils are sampled by horizon type (organic or mineral) to a maximum depth of 30cm. This depth was chosen to capture dynamics in the upper layers of the subsoil or B horizon along with the topsoil, and to match the sampling depth used in the Root biomass and chemistry, periodic data product (DP1.10067.001 ). Following field collection, all soils are measured for moisture and pH, and a subset are also measured for microbial abundance and composition, inorganic nitrogen (N) pools and net transformation rates, and total soil organic carbon (C) and nitrogen (N) concentrations and stable isotopes by external laboratories. Frozen soil for the microbial archive is also collected for many samples, and during peak greenness chemistry bouts, excess air-dried soil is archived in the NEON Biorepository and available upon request. For additional details, see the user guides, protocols, and science designs listed in the Documentation section below. Queries for this data product will return field collection metadata as well as physical and chemical measurements for the specified sites within the specified date range. Summary tables of external lab precision and accuracy for chemistry and stable isotope analyses are included in the expanded package. This data product also provides field and laboratory metadata that can be associated with soil microbial data products; refer to the documentation for the respective soil microbe data products for more details.

Latency:
The expected time from data and/or sample collection in the field to data publication is as follows, for each of the data tables (in days) in the downloaded data package. See the Data Product User Guides for more information.

sls_bgcSubsampling:  60

sls_metagenomicsPooling:  45

sls_soilCoreCollection:  35

sls_soilMoisture:  60

sls_soilpH:  90

sls_soilChemistry: 200

bgc\_CNiso\_externalSummary: 30 
 
ntr_internalLab: 45 

ntr_internalLabBlanks: 45

ntr_externalLab: 180 

ntr_externalSummary: 30
description: Three pre-determined, randomly assigned locations are selected for each sampling event at each of 10 plots distributed throughout a site; sampling locations within a plot are not re-sampled. Soil sampling occurs 1-3 times per year depending on length of growing season, with each site always sampled during the historic peak in vegetation greenness. Soil samples are collected to a maximum depth of 30 cm, with organic and mineral soils sampled separately. Soil coring devices are generally 2-2.25” diameter, although the type of device varies based on local soil types and is recorded in the data and collection protocol. In-situ soil temperature is measured, soil samples are homogenized in the field, and subsamples destined for microbial archive and/or analyses are immediately frozen on dry ice. Gravimetric soil moisture and soil pH analyses are conducted at NEON regional laboratories. Every five years, inorganic N pools (NH4+ and NO3-) are measured on fresh and field-incubated soil cores using potassium chloride (KCl) extractions during all bouts of that year. The difference in N concentration between initial and incubated samples can be used to estimate net N transformation rates, see https://github.com/NEONScience/NEON-Nitrogen-Transformations. Every five years, peak greenness subsamples are analyzed for total organic carbon and total nitrogen concentrations and stable isotopes. Instrumentation: