全球黑土区有机物料还田对土壤有机碳固存影响的Meta分析

黑土有机质含量丰富,但随着农业活动加剧,以及黑土区低温特性的限制,土壤有机质大量流失。不同有机物料还田是提升土壤有机质的重要方式,然而目前仍缺少对不同有机物料还田具体恢复效果及过程的评价。该研究使用Meta分析的方法,对2000年1月—2022年9月经同行评议的文章进行整合分析,综合了41篇文献中2 012个观测值,设定低、中、高年限及碳投入量,评估秸秆还田和有机肥还田对黑土土壤有机碳固存的影响。结果表明,有机肥还田处理的土壤有机碳、土壤总氮、土壤总磷含量均高于秸秆还田。随着处理年限的增加,有机肥还田对于土壤有机碳含量的增加效果优于秸秆还田。此外,不同碳投入的条件下,有机物料还田对于土壤碳固存影响不同,其中在中碳投入的条件下,有机肥还田有机碳含量(65.62%)显著高于秸秆还田(20.07%)。21 a以上的长期中碳投入下有机肥还田更有利于黑土土壤有机碳固存的增加。该研究为黑土区有机物料还田的选择提供科学依据。

Meta analysis of the effects of global organic material returning on soil organic carbon sequestration in Mollisols

Mollisols (from Latin mollis, "soft") are the types of highly fertile soil with a thick layer of humus, high organic matter content, and strong nutrient capacity. The natural granary has played an indispensable role in the crucial agricultural and livestock production activities in many countries. A perfect tradeoff can be required for high crop yields with less nutrient loss in the soil under intensified farming practices. Among them, the organic matter greatly contributes to the high fertility, particularly at the medium to high latitudes in the cold and cool regions. Excessive depletion of organic matter can directly impact grain production in the sustainable development. An important approach to restoring organic carbon can be returning the organic materials to the soil via organic matter incorporation. Two common approaches are employed in conventional cultivation: straw incorporation and organic fertilizer application. However, there is an ongoing debate regarding which one is more beneficial for sequestering organic carbon. It is of significant importance to investigate the conditions under which straw incorporation or organic fertilizer application is more advantageous for carbon sequestration. Additionally, the organic matter incorporation is also dependent on various factors, such as fertilization duration and carbon input. The organic materials vary significantly in the decomposition with the increasing fertilization duration, leading to different effects on the soil organic carbon retention. Carbon input is one of the most important limiting factors in soil organic carbon sequestration and the carbon-to-nitrogen ratio. Previous studies have focused mostly on controlled experiments to investigate the effects of different organic matter incorporation on soil organic carbon sequestration. Less attention was paid to the different fertilization durations and carbon inputs under organic matter incorporation. In this study, a meta-analysis approach was utilized to examine the impact of straw incorporation and organic fertilizer application on soil carbon sequestration under various fertilization durations and carbon inputs in Mollisols. A systematic search of peer-reviewed articles was conducted to apply the following criteria for reliability: 1) The experiments included both laboratory and field trials, consisting of control groups without fertilizer application, and experimental groups with either straw incorporation or organic fertilizer application; 2) The trials were performed on Mollisols to record the latitude, longitude, and climatic conditions of the experimental sites; 3) Relevant indicators of soil property with their means, standard deviations, and the number of replicates was directly extracted from the articles'' text, tables, or figures. A total of 41 articles with 2012 observations were obtained after the screening process. The results indicated that the organic manure return was more effective in increasing the soil organic carbon content, compared with the straw return. There was a significant increase of 42.99% in soil organic carbon, 39.97% in total soil nitrogen, and 74.01% in total soil phosphorus in Mollisols. By contrast, the straw return resulted in a significant increase of 14.96% in soil organic carbon, 15.03% in total soil nitrogen, and 20.03% in total soil phosphorus. Moreover, the organic manure return was more effective than the straw return with the increase of treatment years, in terms of the soil organic carbon content. There were different effects of organic manure return to the field on the soil carbon sequestration under different carbon input conditions. The organic carbon sequestration of organic manure returning to the field can be significantly higher than that of straw under medium carbon input conditions. Some suggestions were proposed that the organic manure return under long-term medium carbon input was more beneficial to the increase of organic carbon sequestration. Overall, the findings can provide valuable insights for the scientific selection of organic materials in the field return in Mollisols.