典型地面覆盖下黄土丘陵区干化土壤深层水分变化研究

Water Variation of Deep Desiccation Soil in Loess Hilly Area under Typical Mulching

为了探寻黄土高原丘陵区干化土壤修复措施,采用野外试验,布设1000 cm深地下土柱,并在土柱表层进行9种不同覆盖处理(种植刺槐、苜蓿、柠条、枣树、早熟禾和覆盖石子、树枝、地布和白色地膜),以土柱表面完全裸露作为对照,用中子土壤水分仪测量0~1000 cm不同深度土壤含水率,通过2014—2018年连续观测数据分析发现:在天然降水条件下刺槐、苜蓿、柠条和枣树处理试验年降水入渗深度表现为逐年减小,最终仅有100 cm,并在试验第2年后土壤含水率一直处在负增长状态,其中刺槐、苜蓿、柠条在第4年时1000 cm土柱水分均被消耗而降低,整个土柱干化程度加重,而枣树耗水较轻,300 cm以下的深层土壤干化程度并未加重;早熟禾年降水入渗深度可达300 cm,试验期间土壤水分消耗量小于当年降水量,0~300 cm以内干化土壤水分得到缓解;石子、树枝、地布和白色地膜的5年最大修复深度可达280、300、580、600 cm;石子和树枝覆盖的土壤水分缓解深度达700 cm,白色地膜和地布覆盖土壤水分缓解深度可达1000 cm;裸露地表在天然降水下土壤水分缓解深度达520 cm,土壤水分修复深度达240 cm。

Soil desiccation is becoming more and more serious in hilly areas of the Loess Plateau,which has become an important factor restricting ecological restoration and reconstruction in the region.To find a solution to the ecological problem of dry soil remediation,a large-scale underground soil column with depth of 1000 cm was planted in the field.Totally nine typical mulches were used on the surface of soil columns,separately for planting Robinia pseudoacacia,alfalfa,Caragana korshinskii,jujube and Poa pratensis,and covering stones,branches,ground cloth and white film.Taking bare soil column as control.Through the analysis of continuous observation data from 2014 to 2018,it was found that under natural precipitation conditions,infiltration depth of Robinia pseudoacacia,alfalfa,Caragana korshinskii and jujube was decreased to 100 cm,after the second year of the experiment,the soil moisture in column was in a negative growth state.In the fourth year(2017),the water content of 1000 cm soil column was reduced by consumption,and the drying degree of the whole soil column was deepened,among them,that planted Robinia pseudoacacia was the most heavy,and that planted jujube was the lightest.Soil moisture in columns of jujube below 300 cm was not increased or consumed.The infiltration depth of Robinia pseudoacacia could reach 300 cm,the water consumption during the experiment was slightly less than that of the current year precipitation,which can alleviate the drying soil within 300 cm.The maximum restoration depths of covering stones,branches,ground cover and white film were 280 cm,300 cm,580 cm and 600 cm during the experiment,respectively.Until the fifth year,the mitigation depth of soil moisture covered with stones and branches reached 700 cm,and that covered with ground cover and white film reached 1000 cm.Covering white film was the best of all.Under natural precipitation,the soil moisture mitigation depth of bare soil column reached 520 cm,and restoration depth reached 240 cm.