| Karst rock desertification is the most serious ecological and environmental geological problem in southwest China,and has become one of the core problems restricting the sustainable development of local society and economy.Karst in southern China,centered on the Guizhou plateau,covers an area of 550,000 km~2,accounting for 13.54%of the national land area,and is the most widely distributed and strongly developed tropical subtropical area in China and the world,with prominent regional soil erosion and leakage problems.As an agronomic measure,soil mulch can significantly improve soil erosion and reduce the degree of soil and water leakage,which is an important tool for soil erosion control and stone desertification management.It is important to strengthen the research of soil mulch interception process and soil and water leakage control technology in agroforestry for karst stone desertification control,to scientifically promote the research and development of leakage control technology in karst area and promote the development of agroforestry industry and stone desertification control.According to the theories of geography,ecology and soil conservation on soil and water loss,erosion control,soil mulching interception and agroforestry configuration in karst areas,the scientific problems and technical needs of the complex factors affecting soil and water loss in karst areas and the urgent need for research and development of soil and water loss control technologies are addressed,and the study is conducted in the highland mountainous area,highland canyon area and mountainous area of Guizhou,which represent the general structure of karst and stone desertification ecological environment in southern China.From 2020 to2023,through field vegetation survey,soil physical and chemical property determination,soil moisture and rainfall monitoring,in situ monitoring,indoor experiments,correlation analysis and other statistical methods,we will conduct systematic research on karst water and soil leakage mechanism,soil mulching interception process,inventions,application demonstration and promotion of agroforestry control technology.The study will focus on clarifying the connection between soil mulching,soil,rainfall characteristics and agroforestry vegetation types,revealing the physicochemical effects of soil mulching on agroforestry soils,proposing suitable agroforestry water and soil leakage control techniques for karst areas,and providing theoretical and scientific references for national stone desertification control.(1)The hydrological process of karst agroforest soil mulching was elucidated,and the differences in soil water recharge characteristics and differences in vertical distribution characteristics of agroforest cover were summarized.The soil water content of each layer in the study area after mulching showed an increasing trend;temporally the water recharge characteristics were influenced by rainfall with an average lag of 2.3h,and the best rainfall absorption level was light rain;each mulch enhanced soil water recharge to different degrees,regulated the recharge rate and increased the recharge efficiency;spatially the mulch had a water storage function,and the water content of the middle layer 20-40 cm was higher,and the water storage effects of walnut+maize agroforestry,Pepper+loquat agroforestry,peach+plum trees agroforestry were SM(28.93%)>SAP+CM(28.83%)>GM(25.02%)>WM(18.90%)>C(17.73%),GM(34.29%)>SM(31.46%)>SAP+CM(28.18%)>C(27.35%),CM(31.24%)>SM(30.43%)>GM(28.89%)>C(23.51%),respectively.It is important to have a deeper understanding of the soil mulching interception process pattern.Observing the average interception effect of different soil mulches can reveal that corn straw mulch has the best effect and its soil water content is the highest,although the undergrowth mulch has obvious effect after reaching a certain period,the mulch has certain requirements on the soil environment of the rocky desertification area.(2)The water and soil leakage control mechanism of karst agroforest soil mulch was revealed,and the differences in soil texture,water holding capacity and fertility characteristics of agroforest mulch were summarized.Soil particle characteristics of agroforestry soils are different,the proportion of clay particles in each soil layer is the smallest,and each mulch can improve soil texture;soil erodibility K correlates higher with sand and organic carbon,followed by clay and silt;pebble gravel+water retention agent and maize straw mulch were the best for improving soil bulking,capillary porosity and water holding capacity in agroforestry,with water holding capacity SM(38.00%)>SAP+CM(37.90%)>GM(36.43%)>WM(33.19%),with significantly higher effects in the wet season than in the dry season;soil fertility is affected by rainfall and leakage occurs.Soil fertility is affected by rainfall,and the lower 40-60 cm is most affected.Undergrowth mulch is the best for improving soil organic matter and total nutrients in agroforestry,followed by cobble gravel+water retention agent and corn straw,and the results are influenced by climate,topography and vegetation.Soil mulch can inhibit karstic desertification,and the mechanism of action is mainly to increase soil surface mulching to reduce soil erosion and block soil and water leakage,which brings theoretical and data support for economic and social development.(3)We proposed the soil and water leakage control technology for karst agroforests and carried out the application demonstration,and constructed three soil mulching interception models for soil and water leakage control in stone desertification.The mulching technology of cobble gravel+water retention agent,undergrowth mulching technology,walnut inner shell mulching technology and corn straw mulching technology were created for agroforests;the application demonstrations were verified in Bijie Salaxi potential-light desertification demonstration study area in karst plateau mountains,Guanling-Zhenfeng Huajiang medium-intensity demonstration study area in karst plateau canyon and Shibing karst without-potential desertification demonstration study area in karst mountain canyon,which represent the type of karst ecosystem in southern China,and confirmed the effectiveness of mulching technology in water storage and nutrient retention,and the application to agroforest ecosystem The application of the mulching technology to agroforestry ecosystems can provide some implications for achieving the soil and water conservation objectives and economic benefits of agroforestry in karst areas,and provide a scientific and technical reference for the national stone desertification control project. |
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