Human wastewater biosolids, hereafter referred to as biosolids, are produced in significant quantities around the world and often applied to an extensive land mass including agricultural fields, forests, mine lands, and urban areas. Land-application of biosolids has been reported in peer-reviewed and non-peer-reviewed work to change soil organic carbon stocks in varying amounts. Determining the potential of soil organic carbon (SOC) stock change and sequestration from biosolids land application is critical for biosolids producers and users to gain access to carbon credit markets. Our review question is, "what is the impact of biosolids application on long-term soil carbon sequestration rates?” We look to explore this main question with the follow-up, "does biosolids processing methods and characteristics, application method, soil properties, land management and other modifiers affect rates of carbon accumulation from land-applied biosolids?" Searches will be conducted using online databases (i.e., Web of Science Core Collection, CAB Abstracts, Scopus, ProQuest Dissertations & Theses Global), search engines (Google Scholar and Microsoft Academic), and specialist websites to find primary field studies and grey literature of biosolids land-application effects on soil organic carbon stocks. We will use English search terms and predefined inclusion criteria of: (1) a field study of at least 24 months that reports soil organic carbon/matter (SOC/SOM) concentrations/stocks; (2) has two types of treatments: (i) a control (non-intervention AND/OR synthetic fertilizer) AND (ii) a biosolids-based amendment; and (3) information of amendment properties and application dates and rates to estimate the relative contribution of the applied materials to SOC changes. We will screen results in two stages: (1) title and abstract and (2) full text. A 10% subset will be screened by two reviewers for inclusion at the title and abstract level and use a kappa analysis to ensure agreement of at least 0.61. All results in the full text stage will be dual screened. Data will be extracted by one person and reviewed by a second person. Critical appraisal will be used to assess studies’ potential bias and done by two reviewers. A meta-analysis using random effects models will be conducted if sufficient data of high enough quality are extracted.

中文翻译：

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施用人类废水中的生物固体（污水污泥）对土壤长期固碳率有何影响？系统的审查协议

人类废水中的生物固体，以下简称生物固体，在世界范围内有大量生产，通常应用于包括农业领域，森林，矿山和城市地区在内的广大土地上。在同行评审和非同行评审的工作中，已报告了生物固体在土地上的应用，以改变土壤有机碳储量的数量。确定土壤有机碳（SOC）储量变化和生物固体土地封存的潜力对于生物固体生产商和用户获得碳信用市场准入至关重要。我们的审查问题是：“生物固体施用对长期土壤固碳率有何影响？” 我们希望通过后续活动来探讨这个主要问题：“生物固体的加工方法和特性，应用方法，（3）修正特性，申请日期和比例的信息，以估算申请材料对SOC变化的相对贡献。我们将分两个阶段筛选结果：（1）标题和摘要以及（2）全文。两名审稿人将筛选10％的子集，以包括在标题和摘要级别，并使用kappa分析以确保至少0.61的一致性。全文阶段的所有结果都将被双重屏蔽。数据将由一个人提取并由另一个人进行审查。关键评估将用于评估研究的潜在偏见，并由两名审稿人进行。如果提取了足够高质量的足够数据，将进行使用随机效应模型的荟萃分析。（1）标题和摘要，以及（2）全文。两名审稿人将筛选10％的子集，以包括在标题和摘要级别，并使用kappa分析以确保至少0.61的一致性。全文阶段的所有结果都将被双重屏蔽。数据将由一个人提取并由另一个人进行审查。关键评估将用于评估研究的潜在偏见，并由两名审稿人进行。如果提取了足够高质量的足够数据，将进行使用随机效应模型的荟萃分析。（1）标题和摘要，以及（2）全文。两名审稿人将筛选10％的子集，以包括在标题和摘要级别，并使用kappa分析以确保至少0.61的一致性。全文阶段的所有结果都将被双重屏蔽。数据将由一个人提取并由另一个人进行审查。关键评估将用于评估研究的潜在偏见，并由两名审稿人进行。如果提取了足够高质量的足够数据，将进行使用随机效应模型的荟萃分析。数据将由一个人提取并由另一个人进行审查。关键评估将用于评估研究的潜在偏见，并由两名审稿人进行。如果提取了足够高质量的足够数据，将进行使用随机效应模型的荟萃分析。数据将由一个人提取并由另一个人进行审查。关键评估将用于评估研究的潜在偏见，并由两名审稿人进行。如果提取了足够高质量的足够数据，将进行使用随机效应模型的荟萃分析。