水蚀风蚀交错区不同土地利用方式的土壤水气传输特性

研究水蚀风蚀交错区土地利用方式转变对土壤水气传输的影响,可为黄土高原生态恢复过程中有限水土资源的高效利用提供参考.为了分析不同土地利用方式下的土壤水气传输特性,探究饱和导水率(K_s)、导气率(K_a)和相对气体扩散率(D_P/D₀)间的关系,对柠条地、撂荒地、苜蓿地、农地和裸地样地0~5 cm深度土层原状土,采用定水头法测定K_s,气室法测定D_P/D₀,土壤导气率测定仪测定田间持水量(FC)下的K_a.结果表明: 土壤0~5 cm容重(ρ_b)的大小顺序为苜蓿地>裸地>撂荒地>柠条地>农地,撂荒地、裸地和苜蓿地ρ_b与农地差异显著.土壤总孔隙度(Φ)的大小顺序为农地>柠条地>撂荒地>裸地>苜蓿地,相比农地,苜蓿地、裸地和撂荒地土壤Φ分别低7.5%、4.7%和3.1%.充气孔隙度(ε₁₀₀)的大小顺序为农地>撂荒地>柠条地>裸地>苜蓿地,苜蓿地、裸地、柠条地和撂荒地ε₁₀₀分别较农地低38.3%、33.6%、12.8%和10.1%.土壤K_s的大小顺序为撂荒地>柠条地>苜蓿地>裸地>农地,其中,撂荒地K_s显著高于其他4种土地利用方式;土壤K_a的大小顺序为撂荒地>苜蓿地>柠条地>裸地>农地,撂荒地与农地之间差异显著;土壤D_P/D₀的大小顺序为撂荒地>柠条地>苜蓿地>农地>裸地,其中,柠条地和撂荒地土壤D_P/D₀显著大于农地,分别较农地高36.8%和61.6%.土壤K_s和FC条件下的K_a、D_P/D₀之间呈显著相关.土地利用方式转变显著改变了土壤的通透性,耕地撂荒或者种植柠条及苜蓿改善了表层土壤导水和导气性能,农地和裸地土壤水气传输能力较差.

The characteristics of soil water and gas transport under different land use patterns in the water-wind erosion crisscross region

Understanding the effects of land use patterns on soil water and gas transport in the water-wind erosion crisscross region can provide guidance for high-efficiency use of limited soil and water resource in the ecological rehabilitation process on the Loess Plateau. To investigate the cha-racteristics of soil water and gas transport under different land use patterns and to study the relationships between soil saturated hydraulic conductivity (K_s), air permeability (K_a) and relative gas diffusivity (D_P/D₀), we collected soil samples (0-5 cm depth) from Caragana korshinskii land, abandoned land, alfalfa land, cropland, and bare land. K_s was measured by constant-head method. D_P/D₀ was measured by gas chamber method. K_a under field capacity (FC) was measured using the soil gas permeability meter. Results showed that soil bulk density (ρ_b) ranked as alfalfa land>bare land>abandoned land>C. korshinskii land >cropland, with that of abandoned land, bare land and alfalfa land being significantly different from that of cropland. Total soil porosity (Φ) ranked as cropland>C. korshinskii land>abandoned land>bare land>alfalfa land. Compared with cropland, Φ of alfalfa land, bare land and abandoned land was lower by 7.5%, 4.7% and 3.1%, respectively. Air filled porosity (ε₁₀₀) ranked as cropland>abandoned land>C. korshinskii land>bare land>alfalfa land. ε₁₀₀ of alfalfa land, bare land, C. korshinskii land and abandoned land was lower by 38.3%, 33.6%, 12.8% and 10.1%, respectively, as compared with cropland. Soil K_s ranked as abandoned land>C. korshinskii land>alfalfa land>bare land>cropland, with that of the abandoned land being significantly higher than the other four land use patterns. Soil K_a ranked as abandoned land>alfalfa land>C. korshinskii land>bare land>cropland, with that of abandoned land being significantly diffe-rent with cropland. Soil D_P/D₀ ranked as abandoned land> C. korshinskii land> alfalfa land>cropland>bare land, in which D_P/D₀ of C. korshinskii land and abandoned land was significantly higher than cropland by 36.8% and 61.6%, respectively. There were significant correlations between K_s and K_a, D_P/D₀ under FC conditions. Land use patterns significantly changed soil permeability. Farmland, abandonment, C. korshinskii, and alfalfa plantation improved hydraulic and gas transport parameters of the surface soil. In contrast, farmland and bare land had poor capability of soil water and gas transport.