Data accuracy and method validation of chemical soil properties in long-term experiments: Standard operating procedures for a non-certified soil laboratory in Latin America

Grahmann, Kathrin; Terra, José A.; Ellerbrock, Ruth H.; Rubio, Valentina; Barro, Raquel; Caamaño, Alejandro; Quincke, Andrés

doi:10.1016/j.geodrs.2022.e00487

Cited by 7 publications

(6 citation statements)

References 46 publications

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“…Long‐term field experiments (LTEs) do not usually represent the average situation on actual farms (Henryson et al, 2022) but are idealized and controlled systems that allow testing of hypotheses related to management practices and crop rotations. They are designed for knowledge improvement, process understanding and scenario building, for example, in relation to changing weather conditions, and are essential for designing sustainable production systems (e.g., Grahmann et al, 2022). In that respect, applied management is very often relatively constant, in order to determine long‐term effects of a specific treatment.…”

Section: Discussionmentioning

confidence: 99%

How does national SOC monitoring on agricultural soils align with the EU strategies? An example using five case studies

Meurer,

Hendriks,

Faber

et al. 2024

European J Soil Science

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Soil functioning contributes to the delivery of a vast range of ecosystem goods and services, and ecosystem health is therefore reflected by the capacity of the soil to perform underlying functions. Soil organic carbon (SOC) is a key indicator for soil quality as it is an integral driver of many soil functions and associated ecosystem services. Across the globe, SOC stocks are declining due to expanding agriculture and unsustainable practices. Awareness of the fact that soil is a non‐renewable resource and its functioning important for all life on Earth is increasing, especially among policymakers. As such, goals for the preservation and restoration of SOC are formulated in policies under the European Green Deal. However, the evaluation of these goals at the European level is hampered by a non‐harmonized diversity in national SOC monitoring strategies. While some SOC indicators can be useful for the evaluation of most policy goals (i.e., baseline and potential SOC stocks), additional and contrasting SOC data are often required for the evaluation of the goals formulated by the different EU directives. This study provides an overview of five ongoing SOC monitoring programmes across Europe and discusses how national programmes may be aligned to evaluate goals at the EU level. Five countries with very different soil monitoring programmes were included in a case study to illustrate the potential for harmonization and standardization of SOC assessment. Based on this study, we conclude that SOC monitoring strategies can be harmonized, but not standardized. We further suggest five sampling strategies that have potential for harmonization under the proposed Directive on Soil Monitoring and Resilience.

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Section: Discussionmentioning

confidence: 99%

How does national SOC monitoring on agricultural soils align with the EU strategies? An example using five case studies

Meurer,

Hendriks,

Faber

et al. 2024

European J Soil Science

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“…SOC and total N (N tot ) were analyzed by dry combustion at 900 °C followed by infrared detection (LECO Truespec; Wright and Bailey (2001). Before 2011, SOC samples were analyzed with the Tinsley method (heated dichromate/titration), therefore SOC values obtained since 2011 were converted using a previous determined factor of 0.81 (Grahmann et al, Forthcoming 2022;in press).…”

Section: Soil Chemical Analysismentioning

confidence: 99%

Soil Use Legacy as Driving Factor for Soil Erosion under Conservation Agriculture

Grahmann

Rubio

Perez‐Bidegain

et al. 2022

Front. Environ. Sci.

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Water erosion can cause irreversible depletions in soil quality and crop productivity. The susceptibility of the soil to erosion is affected by current and historical management practices. Historical soil management practices like ploughing or subsoil loosening may lead to irreversible degradations of soils, which in turn increases soil erosion risk. Six “Wischmeier” plots under conservation agriculture, but with different historic treatments regarding soil use and management, were evaluated. These plots were installed in 1984 in Colonia del Sacramento, Uruguay on a Vertic Argiudoll. The objective of this study was to quantify how changes in soil quality, generated by different historical soil use and management over the last 35 years, contribute to current runoff and soil erosion in a cropping system under soil conservation practices using no-till, residue retention and cover crops. Considering differences in soil legacy effects of previous land use, plots were grouped in three treatments with contrasting historic index of agricultural intensification (IAI). The IAI was developed combining the duration of land use under agricultural production and the number and intensity of tillage activity resulting in the treatments: tillage with crop-pasture rotation (TIL_CP), no-tillage under several rotations (NT_Mix) and tillage with continuous cropping (TIL_CROP) with an increasing IAI of 3.5, 7.1 and 11.8, respectively. Rainfall events, runoff water and total, fixed and volatile solids were studied from 2017 to 2019. Soil physical (bulk density, penetration resistance, infiltration rate, aggregate stability), chemical (soil organic carbon (SOC), pH, phosphorous (P-Bray)) and biological properties (particulate organic matter (POM), potentially mineralizable nitrogen (PMN)) were assessed in 2019. Yearly average runoff amounted 209, 579 and 320 mm in 2017, 2018 and 2019, respectively. Yearly average soil losses were 233, 805 and 139 kg/ha with significant differences among years. The lowest soil losses were observed in TIL_CP (231, 615 and 146 kg/ha in 2017, 2018 and 2019, respectively) with lowest IAI of 3.5. Infiltration rate was the lowest in plots with highest IAI. Soil bulk density was highest (1.3 g/cm3) in plots with high IAI. SOC and PMN were lowest in TIL_CROP (3.0% SOC and 34 mg/kg PMN), holding the highest IAI of 11.8. Conservation agriculture minimized soil erosion losses in all plots and years, and erosion was much lower than the maximum tolerable threshold of 7,000 kg/ha for this particular soil. However, in historically intensively tilled and cropped soils, soil quality showed long-term adverse effects pointing towards a reduced resilience of the agricultural system.

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“…For example, errors in the true SOC determination may occur during the sieving of a sample due to different applied forces and durations resulting in more or less contamination with particulate organic material such as straw and roots <2 mm (Díaz-Zorita et al, 2007;Kowalenko, 2001;Xu et al, 2017). Furthermore, a lack of soil sample homogenization by limited milling facilities (FAO, 2018), or bias due to changing laboratory operators over time (Grahmann et al, 2022), may affect the laboratory result. Changes in field sampling design (Olson et al, 2014), natural heterogeneous soil conditions (Brus, 2021;Poeplau et al, 2016) and landscape heterogeneity and topography (Goidts et al, 2009) may also affect the final SOC determination.…”

Section: Introductionmentioning

confidence: 99%

“…When evaluating long‐term soil data sets, researchers are confronted with several questions about interpreting and managing data uncertainties generated by analytics over time. Commonly, laboratory methods for a specific soil property may change over the lifespan of a LTE, and there is often a lack of method documentation and verification (Davis et al, 2018; Grahmann et al, 2022). However, to guarantee the quality of long‐term soil data and ensuring its correct interpretation, issues associated with the accuracy and bias of analytical methods need to be considered, especially when different analytical equipment is used over time.…”

Section: Introductionmentioning

confidence: 99%

“…National and international assessment studies of SOC stocks, for example, require the application of conversion factors between different SOC methods (Lettens et al, 2007; Petrokofsky et al, 2012). However, this correction factor or mean recovery rate is not universal and depends on the divergence between both methods, but also on the soil type, sample SOC concentration range and its physical composition (Chan et al, 2011; Díaz‐Zorita, 1999; Grahmann et al, 2022). The same applies for the impact of organic fertilizer application and its physical existence in the form of straw and decomposing particulate organic matter in the analyte, which may affect recovery rates between different methods (Carter, 2002; Meersmans et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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The dilemma of analytical method changes for soil organic carbon in long‐term experiments

Grahmann

Zwink

Barkusky

et al. 2023

European J Soil Science

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Long‐term experiments (LTEs) have provided data to modellers and agronomists to investigate changes and dynamics of soil organic carbon (SOC) under different cropping systems. As treatment changes have occurred due to agricultural advancements, so too have analytical soil methods. This may lead to method bias over time, which could affect the robust interpretation of data and conclusions drawn. This study aims to quantify differences in SOC due to changes in dry combustion methods over time, using soil samples of a LTE established in 1963 that focuses on mineral and organic fertilizer management in the temperate zone of Northeast Germany. For this purpose, 1059 soil samples, collected between 1976 and 2008, have been analysed twice, once with their historical laboratory method right after sampling, and a second time in 2016 when all samples were analysed using the same elementary analyser. In 9 of 11 soil sampling campaigns, a paired t‐test provided evidence for significant differences in the historical SOC values when compared with the re‐analysed concentrations of the same LTE sample. In the sampling years 1988 and 2004, the historical analysis obtained about 0.9 g kg−1 lower SOC compared with the re‐analysed one. For 1990 and 1998, this difference was about 0.4 g kg−1. Correction factors, an approach often used to correct for different analytical techniques, could only be applied for 5 of 11 sampling campaigns to account for constant and proportional systematic method error. For this particular LTE, the interpretation of SOC changes due to agronomic management (here fertilization) deviates depending on the analytical method used, which may weaken the explanatory power of the historical data. We demonstrate that analytical method changes over time present one of many challenges in the interpretation of time series data of SOC dynamics. Therefore, LTE site managers need to ensure providing all necessary protocols and data in order to retrace method changes and if necessary recalculate SOC. Highlights A total of 1059 LTE soil samples taken between 1976 and 2008 were re‐analysed for SOC in 2016 Several methodological changes for SOC determination led to significant different SOC concentration in the same sample Interpretation and time series of LTE soil data suffer from consideration of analytical method changes and poor documentation of the same Soil archive establishment, thorough method protocols and diligent proficiency testing after soil method changes ameliorate the dilemma

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Data accuracy and method validation of chemical soil properties in long-term experiments: Standard operating procedures for a non-certified soil laboratory in Latin America

Cited by 7 publications

References 46 publications

How does national SOC monitoring on agricultural soils align with the EU strategies? An example using five case studies

How does national SOC monitoring on agricultural soils align with the EU strategies? An example using five case studies

Soil Use Legacy as Driving Factor for Soil Erosion under Conservation Agriculture

The dilemma of analytical method changes for soil organic carbon in long‐term experiments

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