03790naa a2200301 a 450000100080000000500110000800800410001902400380006010000170009824502010011526000090031650001280032552026760045365300190312965300320314865300180318065300200319865300240321865300130324265300120325570000160326770000190328370000140330270000140331670000160333070000160334677301260336210627412022-03-14       2022    bl uuuu     u00u1 u    #d7 a10.1016/j.geodrs.2022.e004872DOI1 aGRAHMANN, K.  aData accuracy and method validation of chemical soil properties in long-term experimentsbStandard operating procedures for a non-certified soil laboratory in Latin America.h[electronic resource]  c2022  aArticle history: Received 9 May 2021, Revised 20 December 2021, Accepted 2 February 2022, Available online 6 February 2022.  aABSTRACT.- Long-term agricultural experiments (LTE) are essential to detect cumulative treatment effects on soil properties and to design sustainable production systems. However, to ensure high quality of long-term soil data and their correct interpretation, several analytical issues regarding the accuracy and analytical laboratory bias need to be considered. This paper aims to (1) evaluate laboratory precision and trueness of analytical soil data for the evaluation of long-term trends in LTE and to (2) assess the limitations and challenges for non-certified soil laboratories that might compromise the quality of analytical soil data. A data set of internal reference soil materials (IRM) collected over 16?years and interlaboratory data from eleven years were analyzed to verify method precision, trueness, and the subsequent long-term dataset reliability for several soil quality parameters: organic carbon (SOC, determined either by wet or dry combustion), pH (water), extractable phosphorous (either Bray I or citric acid; Bray-P or citric acid-P), and exchangeable potassium (Kexch). Results showed that IRM used by the laboratory were homogenous in terms of physical and chemical composition and appropriate to confirm the precision of long-term soil survey data. The relative standard deviation for repeatability and reproducibility (RSDR) ranged from 1.5% for SOC by wet combustion to 9.5% for citric acid-P. HorRat values (the ratio of the estimated standard deviations of reproducibility and the repeatability found for individual analytical procedures) for all chemical soil properties were within the acceptable ranges of <2.0. Interlaboratory trials for soil pH and SOC showed tolerable standard Z-Scores under 2.0 (Z-Score, calculated from the difference between laboratory results and the assigned value divided by the standard deviation), verifying the trueness of data. The results of this study reinforce the validity of analytical soil data originating from the non-certified laboratory in Uruguay obtaining both precise and true soil quality data over a long period of time for most soil analytes. Nevertheless, the analytical flaws in LTE soil monitoring were revealed and can only be minimized in ongoing and future studies through the inclusion of certified reference material. These recommendations should guide future research activities in LTE studies on analytical data quality management as a requirement for long-term soil monitoring. Finally, the paper proposes a proficiency testing procedure for soil laboratories to achieve and maintain high analytical quality for LTE soil research. © 2022 The Authors. Published by Elsevier B.V.  aData precision  aInternal reference material  aRepeatability  aReproducibility  aSoil organic carbon  aTrueness  aURUGUAY1 aTERRA, J.A.1 aELLERBROCK, R.1 aRUBIO, V.1 aBARRO, R.1 aCAMAÑO, A.1 aQUINCKE, A.  tGeoderma Regional, 2022. Volume 28, Article number e00487. OPEN ACCESS. doi: https://doi.org/10.1016/j.geodrs.2022.e00487