Abstract
We currently have a poor understanding of how different soil sampling methods (pedogenetic horizon versus fixed-depth) influence the evaluation of soil properties. Here, 159 soil profiles were sampled from larch (Larix gmelinii) plantations in northeast China using both the pedogenetic horizon and fixed-depth sampling methods. Analysis of variance was used to determine how sampling method influences the assessment of the spatial variation in the concentration and storage of soil organic C (SOC) and N (SON), as well as how these properties are affected by tree age-group (<20, 20–40, and >40 years). In both the 20 cm (surface) and 80 cm (whole profile) sampling depths, pedogenetic sampling resulted in 1.2- to 1.4-fold higher SOC and SON concentrations than fixed-depth sampling. Surface soil nutrient storage between the two sampling methods was not significantly different, but was it was 1.2-fold higher (p < 0.05) with pedogenetic sampling than with fixed-depth sampling in the whole soil profile. For a given error limit in SOC and SON assessments, fixed-depth sampling had a 60%~90% minimum sampling intensity requirement compared with pedogenetic horizon sampling. Additionally, SOC was 1.1- to 1.3-fold greater in the >40 years age-group than in the <20 years age-group (p < 0.05), while SON was the highest in the 20–40 years age-group (p < 0.05). The total amount of SOC and nutrients in soil is fixed regardless how you sample, it is the different assumptions and different ways of extrapolation from samples to the population that cause sampling by horizon versus fixed depth to lead to different conclusions. Our findings highlight that soil sampling method and tree age-group affect the determination of the spatial variation of SOC and SON and future soil assessments should control for methodological differences.
Highlights
Accurate evaluation of soil properties is important for species-to-location matching during afforestation, precision agroforestry [1,2,3], and the investigation of forest ecological functions such as carbon (C) sequestration and nutrient dynamics [4]
The highest soil organic C (SOC) and soil organic N (SON) concentrations were usually observed at Daqingchuan forest farm (DQC) or Dongshan forest farm (DS), while the lowest values were found in Laoshan experimental station (LS) (Table 2)
Our findings differed from these reports; we showed that pedogenetic sampling typically resulted in much higher SOC and SON than fixed-depth sampling (Table 2), which was 1.05- to 1.2-fold higher for SOC and SON storage and 1.2- to 1.4-fold higher for SOC
Summary
Accurate evaluation of soil properties is important for species-to-location matching during afforestation, precision agroforestry [1,2,3], and the investigation of forest ecological functions such as carbon (C) sequestration and nutrient dynamics [4]. Soil heterogeneity occurs horizontally and vertically [5]; the lack of a standardized sampling procedure to assess soil fertility and C inventory could affect conclusions drawn from different studies. Accounting for the effect of sampling method could improve comparability among studies [6,7], in terms of between-site soil fertility assessments [8]. Forest development with age can increase C storage and recover nutrient levels in soils degraded by long-term agricultural cultivation [9,10,11,12]. Soils can range from being a C sink
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
