Soil microbial activity and community composition: Impact of changes in matric and osmotic potential
Soil microbial activity and community composition: Impact of changes in matric and osmotic potential
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DOI：
10.1016/j.soilbio.2011.02.012
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发表时间：
2011-06-01
影响因子：
9.7
通讯作者：
Burns, Richard G.
中科院分区：
文献类型：
--
作者：
Chowdhury, Nasrin;Marschner, Petra;Burns, Richard G.
随着盐渍土的干燥，剩余溶液相中的盐被浓缩，微生物受到水和渗透胁迫。然而，基质电位（MP）和渗透电位（OP）对微生物活性和群落结构的交互作用知之甚少。我们进行了一项实验，在最佳含水量（微生物活性）下预培养两种非盐渍土壤，一种是沙土，另一种是砂质壤土，但通过添加NaCl获得不同的渗透势。饱和膏体（ECe）的EC在砂土中为1.6 ~ 11.6 dS m(-1)，在砂壤土中为0.6 ~ 17.7 dS m（-1）。预孵育14 d后，将土壤干燥至不同含水量：沙土25-35 g kg(-1)，砂壤土95-200 g kg（-1）。砂土水势（WP，渗透电位+基质电位之和）为-0.7 ~ -6.8 MPa，砂壤土水势为-0.1 ~ -4.4 MPa。在添加磨碎的豌豆秸秆以增加易得底物的浓度后，在14 d内测量呼吸作用，并在试验结束时通过磷脂脂肪酸分析（PLFA）评估微生物群落组成。在一定土壤含水量下，两种土壤的累积呼吸均随渗透势的减小而减小，但土壤含水量的减小对累积呼吸的影响存在差异。在沙地中，最低含水量（WC25）和最低含水量（WC28）的累积呼吸均显著低于最高含水量（WC35）。在砂壤土中，最低含水量（WC95）处理的累积呼吸显著低于仅添加盐的最高含水量（WOOD）处理。在给定WP下，两种土壤的累积呼吸减少量相似，与对照（最佳含水量，未添加盐）相比，在WP -3 MPa下减少了50%。在WP的沙滩上
As saline soils dry, the salt in the remaining solution phase is concentrated and the microbes are subjected to both water and osmotic stress. However, little is known about the interactive effect of matric potential (MP) and osmotic potential (OP) on microbial activity and community structure. We conducted an experiment in which two non-saline soils, a sand and a sandy loam, were pre-incubated at optimal water content (for microbial activity) but different osmotic potentials achieved by adding NaCl. The EC of the saturated paste (ECe) ranged between 1.6 and 11.6 dS m(-1) in the sand and between 0.6 and 17.7 dS m(-1) in the sandy loam. After the 14-day pre-incubation, the soils were dried to different water contents: 25-35 g kg(-1) in the sand and 95-200 g kg(-1) in the sandy loam. Water potential (WP, the sum of osmotic + matric potential) ranged from -0.7 to -6.8 MPa in the sand and from -0.1 to -4.4 MPa in the sandy loam. After addition of ground pea straw to increase the concentration of readily available substrate, respiration was measured over 14 days and microbial community composition was assessed by phospholipid fatty acid analysis (PLFA) at the end of the experiment. In both soils, cumulative respiration at a given soil water content (WC) decreased with decreasing osmotic potential, but the effect of decreasing water content differed between the two soils. In the sand, cumulative respiration at the two lowest water contents (WC25 and WC28) was always significantly lower than that at the highest water content (WC35). In the sandy loam, cumulative respiration was significantly lower at the lowest water content (WC95) compared to the highest water content (WOOD) only in treatments with added salt. The reduction of cumulative respiration at a given WP was similar in the two soils with a 50% reduction compared to the control (optimal water content, no salt added) at WP -3 MPa. In the sand at WP