Turnover of organic matter in differently textured soils: II. Microbial activity as influenced by soil water regimes
Turnover of organic matter in differently textured soils: II. Microbial activity as influenced by soil water regimes
复制标题
DOI：
10.1016/s0016-7061(98)00084-6
复制
发表时间：
1999-05
期刊：
影响因子：
6.1
通讯作者：
I. Thomsen;P. Schjønning;Bendt Jensen;K. Kristensen;B. Christensen
中科院分区：
文献类型：
--
作者：
I. Thomsen;P. Schjønning;Bendt Jensen;K. Kristensen;B. Christensen
为了评价土壤质地和土壤含水量对有机碳（OC）分解的影响，研究了12种来源和种植历史相似的不同质地土壤中部分稳定的~（14）C标记的黑麦草残体在4种基质势下的周转。六种土壤来自天然存在的粘土梯度，粘土含量分别为11、16、21、31、37和45%（称为NA 1至NA 6）。通过将从NA 2土壤中提取的粘土或淤泥大小的有机矿物复合物添加到部分NA 1土壤中来制备三种粘土改良土壤（CL 2、CL 4、CL 6）和三种淤泥改良土壤（SI 2、SI 4、SI 6）。在14 C标记的黑麦草在类似田间的条件下分解8个月后，对土壤芯进行取样，调整到四种基质势（−30、−100、−500和−1500 hPa），并在20°C下培养15周。NA土壤的有机碳含量与土壤质地无关。土壤有机碳含量增加，粘土和粉砂在CL和SI土壤中，因为OC所含的应用大小分离。从CL和SI土壤的相对CO2-演变是低于从质地相应的NA土壤，表明与粘土单独比散装OC提供的C周转较慢。土壤水分参数比土壤质地组成更能解释14 C-黑麦草残体和土壤有机碳分解能力的差异。在每一组土壤中，从原生SOC的CO2的演变是高度相关的体积含水量。14 CO2释放量与土壤孔隙持水量的相关性显著提高，而与直径大于0.2 μm的土壤孔隙持水量的相关性显著提高。这表明，可用于从黑麦草和本地SOC的残留物的营业额的水被保留在孔隙体积的不同部分。我们的研究表明，水是主要因素，在控制营业额的SOC。质地的影响是间接的，并通过土壤结构，这反过来又定义了土壤孔隙系统，从而土壤的能力，以保持不同的可用水的分解生物。
To evaluate the effect of soil texture and soil water content on decomposition of organic carbon (OC), turnover of partially stabilized14C -labelled ryegrass residues was studied at four matric potentials in twelve differently textured soils of similar origin and cropping history. Six soils were from a naturally occurring clay gradient and had 11, 16, 21, 31, 37 and 45% clay (termed NA1 to NA6). Three clay-amended soils (CL2, CL4, CL6) and three silt-amended soils (SI2, SI4, SI6) were prepared by adding clay or silt sized organomineral complexes extracted from the NA2 soil to a portion of the NA1 soil. After14C -labelled ryegrass had decomposed for eight months under field-like conditions, soil cores were sampled, adjusted to four matric potentials (−30, −100, −500 and −1500 hPa) and incubated at 20°C for 15 weeks. The content of native soil organic carbon (SOC) in the NA soils was not related to texture. The SOC content increased with clay and silt in the CL and SI soils because of OC contained in the applied size separates. The relative CO2-evolution from CL and SI soils was lower than from the texturally corresponding NA soils, indicating a slower turnover of C supplied with the clay separate than of bulk OC. Differences in the decomposability of native SOC and residues of14C -ryegrass were better explained by soil moisture parameters than by soil textural composition. Within each set of soils, evolution of CO2from native SOC was highly correlated with the volumetric water content. The same was true for14CO2-evolution, but correlations were significantly improved when14CO2was related to water retained in soil pores with diameters >0.2 μm. This indicated that the water available for the turnover of residues from ryegrass and of native SOC was retained in different fractions of the pore volume. Our study suggested that water was the main factor in controlling turnover of SOC. Texture effects were indirect and expressed through soil structure which in turn defined the soil pore system and thus the ability of the soils to retain water of different availability to the decomposer organisms.