【作者】 杜慧平；

【导师】 李小刚；

【作者基本信息】 甘肃农业大学 ， 土壤学， 2007， 硕士

【摘要】 增加土壤有机质(碳)含量能有效地改善土壤的物理性质,相关的报道很多,但对于高寒草地土壤有机碳组分之间及有机碳组分与土壤物理性质之间关系的直接研究并不多见。本文针对高寒地区(0~30cm)六种草地类型(51个土样)土壤有机碳组分以及有机碳组分与土壤物理性质之间的相关性进行了研究,旨在使人们能够更清楚的了解土壤有机碳组分并真正认识到其生态学意义。主要研究结论如下:1.微生物量碳、矿化碳、粗有机碳(2～0.1 mm)、稳定有机碳(<0.05 mm)、水溶性有机碳、焦磷酸钠提取土壤有机碳(腐殖质有机碳)以及碳水化合物碳含量和土壤总有机碳含量之间均呈显著线性正相关,其中焦磷酸钠提取土壤有机碳含量与总有机碳含量之间最相关(r=0.91,p<0.001),这说明土壤总有机碳含量的变化在很大程度上依赖于焦碳磷酸钠提取土壤有机碳的含量。有机碳颗粒粒径组分粗有机碳、稳定有机碳含量与焦磷酸钠提取有机碳含量之间均显著线性正相关。浓酸(浓度为12M的硫酸)、稀酸(浓度为0.5M的硫酸)和热水提取碳水化合物碳含量与粗有机碳以及矿化碳含量之间的相关性均达到了极显著水平,这说明碳水化合物碳主要分布在粗有机碳中,是容易矿化的有机碳组分。微生物量碳和矿化碳(培养50天)含量分别与粗有机碳、焦磷酸钠提取有机碳、水溶性有机碳以及碳水化合物碳含量之间均显著线性正相关,且矿化碳和粗有机碳的相关性最高(r=0.93,p<0.001),这说明在本研究中矿化碳主要来自于粗有机碳组分,粗有机碳是土壤微生物主要的呼吸基质。2.试验就高寒草地(0-30cm)的土壤物理性质(>0.25mm水稳性团聚体平均重量直径(MWD)、颗粒密度、容重、孔隙度以及土壤最大持水量)与土壤有机碳含量之间的关系做了研究,以评价高寒地区土壤有机碳库变化致使土壤物理性质退化,从而导致土壤的严重恶化,造成水土流失的状况。研究结果表明,容重(p<0.001)和颗粒密度(p<0.001)与土壤总有机碳含量均显著线性负相关;水稳性团聚体平均重量直径(p<0.001)、孔隙度(p<0.01)和最大持水量(p<0.001)与土壤总有机碳含量均显著线性正相关;水稳性团聚体平均重量直径与腐殖质有机碳、稳定有机碳、浓酸提取碳水化合物碳和稀酸提取碳水化合物碳含量之间均呈显著线性正相关;与粗有机碳、微生物量碳、矿化碳和热水提取碳水化合物碳之间无相关性。以上结果说明并不是所有有机碳都影响着土壤团聚体的稳定性。3.本研究得出土壤团聚体稳定性主要受有机碳组分中腐殖质有机碳、稳定有机碳和浓酸、稀酸提取碳水化合物碳含量的影响,它们之间的相关性系数大小顺序为稳定有机碳(r=0.62)>稀酸提取碳水化合物碳(r=0.49)>腐殖质有机碳(r=0.47) >浓酸提取碳水化合物碳(r=0.46)。高寒地区的土壤系统非常脆弱,开垦、过度放牧等人为干扰造成土壤有机碳库的减少,从而降低土壤团聚体的稳定性,潜在的加速土壤侵蚀和降低土壤的通透性和持水能力,严重地威胁着高寒草地土壤的生态功能。更多还原

【Abstract】 Generally believing, increasing the content of soil organic matter can effectively improve the soil physical properties. However, correlations between soil organic carbon fractions themselves and theirs with variable links to soil physical properties in an alpine pastureland have not be well understood. Aim of this study was to investigate relationships of soil organic carbon fractions and their soil physical properties (in the depth of 30cm, six pastureland and 51 soil samples) and therefore further we may know their value of economy. The main conclusion as follows:1. Significant positive linear relationships were found between microbial biomass carbon, coarse organic carbon, stable organic carbon, water-soluble organic carbon, humus organic carbon, carbohydrate carbon and total organic carbon. Meanwhile, linear relationships between humus organic carbon and the total organic carbon(r=0.91, p<0.001) were most significant which indicated that the contents of total organic carbon are based on the humus organic carbon. The coarse organic carbon and stable organic carbon was positive linear relationships to the humus organic carbon. A positive and high relationship was found between carbohydrate carbon contents and coarse organic carbon, microbial biomass carbon and Mineralized C which showed important relation of carbohydrate carbon contents and microbial biomass, carbohydrate carbon mainly being among coarse organic carbon and easy mineralized. Microbial biomass carbon and mineralized C was associated with coarse organic carbon, humus organic carbon, water-soluble organic carbon and carbohydrate carbon. The Mineralized C presented the highest correlation with coarse organic carbon(r=0.93, p<0.001), showing Mineralized C coming mainly from coarse organic carbon fraction, the coarse organic carbon is a mainly basic of soil microbial breath.2. Correlation between fractions soil physical properties( in water stability of >0.25mm aggregates MWD(mean weight diameter), particle density, bulk density, porosity , water holding capacity of soils) and grassland soil organic carbon were also evaluated relative to soil physical degradation. There a passive and high relationship between bulk density and particle density(p<0.001) and soil total organic carbon, whereas between water stable aggregate MWD , porosity , water holding capacity and soil total organic carbon presented positive and high correlation(p<0.001), showing it was important that effects of soil organic carbon on soil physical properties. Water stable aggregate MWD presented high correlation with humus organic carbon, stable organic carbon, concentrated-acid extracted carbohydrate-C, diluted-acid extracted carbohydrate-C and low correlation and coarse organic carbon, microbial biomass carbon, mineralized C, Hot-water extracted Carbohydrate-C. This result showed that some of all organic carbon influence on water stable aggregate.3. The research shows in alpine region that soil water stability of aggregate MWD was mainly affected by humus organic carbon, stable organic carbon, concentrated-acid extracted carbohydrate-C and diluted-acid extracted carbohydrate-C, and correlation coefficient(r) is stable organic carbon(r=0.62)>diluted-acid extracted carbohydrate-C(r=0.49) > humus organic carbon(r=0.47) >concentrated-acid extracted carbohydrate-C(r=0.46). Our results indicated that soil system in alpine region was very frangible, soil managements in present study reduced soil organic pool, which lowed soil stability of aggregate and accelerated loss of soil with water, therefore threaten ecological function of soil.更多还原