不同气候与施肥条件下农田土壤微生物生物量特征与容量分析

【目的】土壤微生物生物量是土壤生物肥力的重要指标,是土壤养分重要的周转库。探讨不同气候和施肥条件下土壤微生物生物量(生物量碳、氮)的特征及容量,对于深刻认识土壤微生物生物量的影响因素及提高土壤生物肥力具有重要意义。【方法】本研究从中国知网、万方和web of Science 3个文献数据库,以"土壤微生物生物量"、"中国农田"和"长期施肥"为关键词,共收集目标文献42篇,包括458组含土壤有机碳(SOC)与土壤微生物生物量碳(SMBC)和414组含土壤全氮(TN)与土壤微生物生物量氮(SMBN)的数据集,涵盖了4种气候下的2类施肥条件(施有机肥:单施或配施,+OM;不施有机肥:无肥和化肥,-OM)。土壤微生物熵(SMBC/SOC)和SMBN/TN的中值差异性均采用Kruskal-Wallis H单向显著性检验(P0.05),容量分析采用界限分析方法。【结果】统计分析结果表明,不同施肥处理下,SMBC与SOC和SMBN与TN之间均存在显著线性正相关关系(P0.01),长期施用有机肥条件下,土壤微生物生物量碳、氮对土壤有机碳和全氮增加的响应系数分别为24.77和30.27,显著高于化肥或不施肥条件(分别为19.88和19.86)(P0.05)。界限分析结果显示,不同施肥措施下SMBC对SOC增加响应的最大值为33.45—36.00,SMBN对TN的最大响应系数为45.45—49.79,当前条件下SMBC和SMBN还有37.99%和49.66%的提升空间。不同气候条件下SMBC/SOC和SMBN/TN均存在显著差异(P0.05),其中,中温带半干旱半湿润区SMBC/SOC的中值最高为2.73%,其次为亚热带湿润区(2.45%)和暖温带湿润区(2.31%),中温带湿润区最低为1.48%;SMBN/TN的中值大小顺序为:暖温带湿润区(4.72%)中温带半干旱半湿润区(3.50%)亚热带湿润区(2.99%)中温带湿润区(1.80%)。不同施肥条件下SMBC/SOC和SMBN/TN的变化范围分别为0.35%—6.50%和0.50%—9.72%,但其中值并无显著差异(P0.05)。对于同一气候条件不同施肥措施而言,仅在中温带湿润区,施有机肥处理对微生物量碳(氮)占总有机碳(氮)的比例有显著影响(P0.05)。【结论】气候对土壤微生物生物量碳、氮所占比例具有显著影响,不同施肥模式虽然不能显著改变微生物生物量碳、氮的比例,但有机肥的施用对微生物生物量碳、氮的提升效果显著高于化肥或不施肥,该结果对于土壤生物肥力的调控有重要指导意义。

Capacity and Characteristics of Soil Microbial Biomass Under Various Climate and Fertilization Conditions Across China Croplands

【Objective】Soil microbial biomass is an important index of soil biological fertility and also is an important pool of soil nutrient turnover. The objective of this study was to explore the capacity and characteristics of soil microbial biomass carbon (SMBC) and nitrogen (SMBN) under various climatic zones and fertilization managements across China cropland, and further to obtain better understanding of the factors and how to manage soil biological fertility.【Method】The publications were collected by searching Web of China Knowledge Resource Integrated Database, Wan Fang Database and Web of Science with the keywords of "soil microbial biomass", "Chinese cropland" and "long-term fertilization". A data set with 458 pairs of reported soil organic carbon (SOC) and SMBC and 414 pairs of reported total nitrogen (TN) and SMBN was set up from 42 published papers. They included such four categories of climatic zone as typical temperate (M1: humid; M2: semi-arid), warm-temperate (W) and subtropical (S) zones and two categories of fertilization with (+OM) and without (-OM) organic amendments across China. Statistical analysis on the median of SMBC/SOC and SMBN/TN under different fertilization managements and climate zones was performed with Kruskal-Wallis H test (P<0.05). The capacity of SMBC and SMBN to SOC and TN was obtained from boundary line, respectively.【Result】Results showed that there was a significant response of soil microbial biomass (SMBC and SMBN) to the increase in SOC and TN under different fertilization managements and climate zones (P<0.01), respectively. The response coefficients (i.e., the correlation slope) between SMBC and SOC, SMBN and TN were 24.77 and 30.27 under organic amendments, respectively, which were significantly higher than that under the management without organic amendments (19.88 for SMBC and 19.86 for SMBN) (P<0.05). Boundary analysis showed that the maximum response coefficients of SMBC to SOC and SMBN to TN were 33.45-36.00 and 45.45-49.79, respectively. Compared with the maximum values, the current average values still have 37.99% and 49.66% of room for improvement, respectively. The median values of SMBC/SOC and SMBN/TN were significantly different among the four climate zones. The highest value of SMBC/SOC was 2.73% under temperate semi-arid and sub-humid zone (M2), followed by sub-tropical (S, 2.45%) and warm humid zone (W, 2.31%), the lowest value is 1.48% under temperate humid zone (M1). The sequence of SMBN/TN was W (4.72%) >M2 (3.50%) >S (2.99%) >M1 (1.80%). The ranges of SMBC/SOC and SMBN/TN were 0.35%-6.50% and 0.50%-9.72%, respectively, under various fertilization conditions with no significant differences. For different fertilization managements under similar climatic zone, the median value of SMBC/SOC and SMBN/TN was significantly higher under organic fertilizer management than that under no organic fertilizer management under temperate humid zone (P<0.05).【Conclusion】Climatic conditions have a significant impact on soil microbial biomass capacity. Different fertilization managements do not significantly change the SMBC/SOC and SMBN/TN, but the organic amendment can significantly improve SMBC and SMBN, which are helpful for soil biological fertility improvement.