CAJ | 학술논문

为了评价农地撂荒对土壤抗侵蚀性的影响,该文以黄土丘陵区自然撂荒地为研究对象,应用时空互代法,通过原状土冲刷试验对不同撂荒阶段(0~43 a)的坡地土壤抗冲性进行了研究.结果表明:与对照(阶段Ⅰ)相比,随着撂荒年限的增加,表层(0~15 cm)和中层(>15~30 cm)土壤容重显著降低,而下层(>30~50 cm)土壤容重变化较小(约下降0.5%).土壤团聚体和抗剪强度(黏聚力C和内摩察角φ)在3个土层中均呈显著增加趋势,而土壤崩解速率在3个土层中均呈下降趋势,与表层相比,中层和下层土壤崩解速率减小幅度更大(约4.2和1.8倍).土壤抗冲性随着撂荒年限的增大在表层呈先增加后稳定的趋势,在中层呈稳定增加而下层无显著变化,与对照相比,中层和下层土壤抗冲系数分别平均增大76.9%和30.7%.土壤团聚体和根系密度在3个土层中均是影响土壤抗冲性的关键因子.研究结果从土壤抗侵蚀性的角度为退耕还林工程的生态功能评价提供理论依据.
위료평개농지략황대토양항침식성적영향,해문이황토구릉구자연략황지위연구대상,응용시공호대법,통과원상토충쇄시험대불동략황계단(0~43 a)적파지토양항충성진행료연구.결과표명:여대조(계단Ⅰ)상비,수착략황년한적증가,표층(0~15 cm)화중층(>15~30 cm)토양용중현저강저,이하층(>30~50 cm)토양용중변화교소(약하강0.5%).토양단취체화항전강도(점취력C화내마찰각φ)재3개토층중균정현저증가추세,이토양붕해속솔재3개토층중균정하강추세,여표층상비,중층화하층토양붕해속솔감소폭도경대(약4.2화1.8배).토양항충성수착략황년한적증대재표층정선증가후은정적추세,재중층정은정증가이하층무현저변화,여대조상비,중층화하층토양항충계수분별평균증대76.9%화30.7%.토양단취체화근계밀도재3개토층중균시영향토양항충성적관건인자.연구결과종토양항침식성적각도위퇴경환림공정적생태공능평개제공이론의거.
The abandoned land plays an important role in degraded ecosystem restoration. Large areas of abandoned land and the relatively little disturbance by human activity made it the optimal mode in the process of the project to “convert the farmland into forestland.”Our objective was to determine the impact of abandoned land and their different stages on soil anti–scouribility (AS) and related soil physical properties. In this paper, five natural lands with various abandoned stages (0-43 a) were selected to study the soil AS by using a spatio–temporal substitution method in the Hilly Loess Plateau. Rectangular, undisturbed soil samples (length=20 cm, width=10 cm, and height=10 cm) were taken in the field and were conducted with a hydrological flume (length=2 m, width=0.10 m). The flume contained an opening at its lower base, equaling the size of a metal sampling box, so that the soil surface of the sample was at the same level of the flume surface. The space between the sample box and the flume edges was sealed with a painter’s mastic to prevent edge effects. The slope of the flume bottom could be varied and clear tap water flow was applied at an adjusted rate of 4.03 L/min discharge on a washing flume slope of 15°for 15 minutes. During the 15 minutes of each experiment, samples of runoff and detached soil was collected every one minute in the first three minutes and two minutes in the following time using 10 L buckets for determination of sediment concentration. Before being tested, the aboveground biomass was cut level with the soil surface. In this way, only the effects of roots were accounted for. The physical properties mainly included soil bulk density (g/cm3), soil water–stable aggregate content (%), soil shear strength (cohesion C and angle of internal frictionφ), and soil disintegration rate (cm3/min). Root biomass was determined by the harvest method and dried in the oven. The results indicated that as the years of the abandoned land increased, compared with control (stageⅠ), soil bulk density in the surface layer (0-15 cm) and middle layer (>15-30 cm) were significantly reduced, while little change occurred in the lower soil layer (>30-50 cm). The soil water–stable aggregate content and shear strength, including C andφwere also significantly increased in the three studied soil layers. Soil disintegration rate was reduced in all soil layers, especially for the middle and lower soil layers, about 4.2 and 1.8 times the rate of those in the surface soil layer. Soil AS in the surface layer increased rapidly before stageⅢ, and kept stable in the following abandoned stages, while the soil AS in the middle and lower soil layers increased steadily, in approximately 76.9%and 30.7%increments as compared with those of the control. Linear regression equations between the soil AS and the soil physical properties studied in the present paper were well fitted in the three soil layers and the soil water–stable aggregate content and dry root biomass were the determining factors in the reinforcement of soil AS in the abandoned land of the Hilly Loess Plateau.