How long before a change in soil organic carbon can be detected?

Research output: Contribution to journalArticle

159 Citations (Scopus)

Abstract

When planning sampling in an experiment where soil organic carbon (SOC) content is expected to change, it is necessary to know how many samples will need to be taken to demonstrate a change in SOC and after how long this change will be detectable. Much has been published on the number of samples required to demonstrate the minimum detectable difference in SOC, but less on how long it takes for this change to be detectable. In this paper, a model of SOC dynamics is used to estimate the minimum time taken for a change in total SOC content to become measurable under different carbon inputs, land uses and soil types.

For free air carbon dioxide enrichment (FACE), and other experiments in which SOC is expected to increase, relationships between the percentage change in C inputs and the time taken to measure a change in SOC are presented, for two levels of sampling intensity corresponding to the maximum that is practically possible in most experiments (similar to100 samples) and that used regularly in field experiments (10-20 samples).

In FACE experiments, where C inputs increase by a maximum of about 20-25%, SOC change could be detected with 90% confidence after about 6-10 years if a sampling regime allowing 3% change in background SOC level (probably requiring a very large number of samples) were used, but could not be detected at all if a sampling regime were used that allowed only a 15% change in background SOC to be detected. If increases in C inputs are much below 15%, it might not be possible to detect a change in soil C without an enormous number of samples. Relationships between the change in C inputs and the time taken to measure a change in SOC are robust over a range of soil types and land uses.

The results demonstrate how models of SOC dynamics can be used to complement statistical power analyses for planning when, and how intensively, to sample soils during experiments. An advantage of the modelling approach demonstrated here is that estimates of the minimum time taken for a change in soil carbon to become detectable can be made, even before any detailed soil samples are taken, simply from estimates of the likely increase in carbon inputs to the soil (via expected changes in net primary production).

Original languageEnglish
Pages (from-to)1878-1883
Number of pages5
JournalGlobal Change Biology
Volume10
Issue number11
DOIs
Publication statusPublished - Nov 2004

Keywords

  • carbon mitigation
  • carbon sequestration
  • FACE experiment
  • Kyoto protocol
  • long-term experiment
  • minimum detectable difference
  • soil organic carbon
  • verification
  • TERM EXPERIMENTS
  • CO2 ENRICHMENT
  • MATTER DYNAMICS
  • STORAGE
  • FOREST
  • TURNOVER
  • MODELS

Cite this

How long before a change in soil organic carbon can be detected? / Smith, Peter.

In: Global Change Biology, Vol. 10, No. 11, 11.2004, p. 1878-1883.

Research output: Contribution to journalArticle

@article{259c3b5dd67f46f0bc619ccc51c92d34,
title = "How long before a change in soil organic carbon can be detected?",
abstract = "When planning sampling in an experiment where soil organic carbon (SOC) content is expected to change, it is necessary to know how many samples will need to be taken to demonstrate a change in SOC and after how long this change will be detectable. Much has been published on the number of samples required to demonstrate the minimum detectable difference in SOC, but less on how long it takes for this change to be detectable. In this paper, a model of SOC dynamics is used to estimate the minimum time taken for a change in total SOC content to become measurable under different carbon inputs, land uses and soil types.For free air carbon dioxide enrichment (FACE), and other experiments in which SOC is expected to increase, relationships between the percentage change in C inputs and the time taken to measure a change in SOC are presented, for two levels of sampling intensity corresponding to the maximum that is practically possible in most experiments (similar to100 samples) and that used regularly in field experiments (10-20 samples).In FACE experiments, where C inputs increase by a maximum of about 20-25{\%}, SOC change could be detected with 90{\%} confidence after about 6-10 years if a sampling regime allowing 3{\%} change in background SOC level (probably requiring a very large number of samples) were used, but could not be detected at all if a sampling regime were used that allowed only a 15{\%} change in background SOC to be detected. If increases in C inputs are much below 15{\%}, it might not be possible to detect a change in soil C without an enormous number of samples. Relationships between the change in C inputs and the time taken to measure a change in SOC are robust over a range of soil types and land uses.The results demonstrate how models of SOC dynamics can be used to complement statistical power analyses for planning when, and how intensively, to sample soils during experiments. An advantage of the modelling approach demonstrated here is that estimates of the minimum time taken for a change in soil carbon to become detectable can be made, even before any detailed soil samples are taken, simply from estimates of the likely increase in carbon inputs to the soil (via expected changes in net primary production).",
keywords = "carbon mitigation, carbon sequestration, FACE experiment, Kyoto protocol, long-term experiment, minimum detectable difference, soil organic carbon, verification, TERM EXPERIMENTS, CO2 ENRICHMENT, MATTER DYNAMICS, STORAGE, FOREST, TURNOVER, MODELS",
author = "Peter Smith",
year = "2004",
month = "11",
doi = "10.1111/j.1365-2486.2004.00854.x",
language = "English",
volume = "10",
pages = "1878--1883",
journal = "Global Change Biology",
issn = "1354-1013",
publisher = "John Wiley & Sons, Ltd (10.1111)",
number = "11",

}

TY - JOUR

T1 - How long before a change in soil organic carbon can be detected?

AU - Smith, Peter

PY - 2004/11

Y1 - 2004/11

N2 - When planning sampling in an experiment where soil organic carbon (SOC) content is expected to change, it is necessary to know how many samples will need to be taken to demonstrate a change in SOC and after how long this change will be detectable. Much has been published on the number of samples required to demonstrate the minimum detectable difference in SOC, but less on how long it takes for this change to be detectable. In this paper, a model of SOC dynamics is used to estimate the minimum time taken for a change in total SOC content to become measurable under different carbon inputs, land uses and soil types.For free air carbon dioxide enrichment (FACE), and other experiments in which SOC is expected to increase, relationships between the percentage change in C inputs and the time taken to measure a change in SOC are presented, for two levels of sampling intensity corresponding to the maximum that is practically possible in most experiments (similar to100 samples) and that used regularly in field experiments (10-20 samples).In FACE experiments, where C inputs increase by a maximum of about 20-25%, SOC change could be detected with 90% confidence after about 6-10 years if a sampling regime allowing 3% change in background SOC level (probably requiring a very large number of samples) were used, but could not be detected at all if a sampling regime were used that allowed only a 15% change in background SOC to be detected. If increases in C inputs are much below 15%, it might not be possible to detect a change in soil C without an enormous number of samples. Relationships between the change in C inputs and the time taken to measure a change in SOC are robust over a range of soil types and land uses.The results demonstrate how models of SOC dynamics can be used to complement statistical power analyses for planning when, and how intensively, to sample soils during experiments. An advantage of the modelling approach demonstrated here is that estimates of the minimum time taken for a change in soil carbon to become detectable can be made, even before any detailed soil samples are taken, simply from estimates of the likely increase in carbon inputs to the soil (via expected changes in net primary production).

AB - When planning sampling in an experiment where soil organic carbon (SOC) content is expected to change, it is necessary to know how many samples will need to be taken to demonstrate a change in SOC and after how long this change will be detectable. Much has been published on the number of samples required to demonstrate the minimum detectable difference in SOC, but less on how long it takes for this change to be detectable. In this paper, a model of SOC dynamics is used to estimate the minimum time taken for a change in total SOC content to become measurable under different carbon inputs, land uses and soil types.For free air carbon dioxide enrichment (FACE), and other experiments in which SOC is expected to increase, relationships between the percentage change in C inputs and the time taken to measure a change in SOC are presented, for two levels of sampling intensity corresponding to the maximum that is practically possible in most experiments (similar to100 samples) and that used regularly in field experiments (10-20 samples).In FACE experiments, where C inputs increase by a maximum of about 20-25%, SOC change could be detected with 90% confidence after about 6-10 years if a sampling regime allowing 3% change in background SOC level (probably requiring a very large number of samples) were used, but could not be detected at all if a sampling regime were used that allowed only a 15% change in background SOC to be detected. If increases in C inputs are much below 15%, it might not be possible to detect a change in soil C without an enormous number of samples. Relationships between the change in C inputs and the time taken to measure a change in SOC are robust over a range of soil types and land uses.The results demonstrate how models of SOC dynamics can be used to complement statistical power analyses for planning when, and how intensively, to sample soils during experiments. An advantage of the modelling approach demonstrated here is that estimates of the minimum time taken for a change in soil carbon to become detectable can be made, even before any detailed soil samples are taken, simply from estimates of the likely increase in carbon inputs to the soil (via expected changes in net primary production).

KW - carbon mitigation

KW - carbon sequestration

KW - FACE experiment

KW - Kyoto protocol

KW - long-term experiment

KW - minimum detectable difference

KW - soil organic carbon

KW - verification

KW - TERM EXPERIMENTS

KW - CO2 ENRICHMENT

KW - MATTER DYNAMICS

KW - STORAGE

KW - FOREST

KW - TURNOVER

KW - MODELS

U2 - 10.1111/j.1365-2486.2004.00854.x

DO - 10.1111/j.1365-2486.2004.00854.x

M3 - Article

VL - 10

SP - 1878

EP - 1883

JO - Global Change Biology

JF - Global Change Biology

SN - 1354-1013

IS - 11

ER -