Soil and water conservation method for camellia oleifera forest in hilly area

Abstract

The application discloses a soil and water conservation method for camellia oleifera forest in hilly areas, which comprises the following steps: zoning and land preparation of the forest land in the hilly areas, setting intermittent terraces and original soil belts along contour lines in the slope cultivation area, constructing a soil stabilizing structure and a water seepage buffer layer on the water-facing side of the terraces to reduce erosion and promote seepage, setting a water collecting and releasing ditch in the inner side of the terraces to slow down runoff, setting a soil and water preserving composite layer in the camellia oleifera planting hole, and setting a sand sink in the slope foot water collecting area to recover runoff. The method can weaken the slope runoff scouring by zoning and land preparation of the forest land in the hilly areas and setting intermittent terraces and original soil belts along contour lines in the slope cultivation area. The soil stabilizing structure, the water seepage buffer layer and the water collecting and releasing ditch are combined to realize runoff reduction and water storage. The soil and water preserving composite layer in the camellia oleifera planting hole can enhance the root zone stability and water holding capacity, so that the soil and water loss can be effectively controlled and the water use efficiency can be improved without large-scale hard engineering.

Description

Technical Field

[0001] This invention relates to the field of soil and water conservation methods, and more particularly to a soil and water conservation method for camellia oleifera forests in hilly areas. Background Technology

[0002] Camellia oleifera, as an important woody oilseed tree species in hilly and mountainous areas, often requires orchards to be established in hilly areas with steep slopes and significant topographic relief. However, such terrain is generally characterized by high frequency of soil erosion, insidious erosion processes, and significant cumulative effects due to factors such as rainfall runoff accumulation, poor slope soil stability, and easily disturbed soil structure. Under conditions of heavy or continuous rainfall, slope runoff easily forms confluence channels on the slope, carrying fine soil particles downhill, leading to the erosion of the topsoil, the loosening of the root zone soil, and damage to the soil pore structure in the planting area. This results in root instability, reduced water and fertilizer retention capacity, and affects the survival rate of young trees. Furthermore, hilly terrain... Camellia oleifera forests in hilly areas often suffer from the problem of "rapid drainage of water during the rainy season and significant water shortage in the root zone during the dry season." Rainwater resources are difficult to effectively retain on the slope and be converted into soil water that can be used by the roots, resulting in uneven water distribution and frequent droughts. In addition, existing soil and water conservation measures for Camellia oleifera forests on hilly slopes tend to focus on a single approach, making it difficult to balance water retention and soil moisture conservation with root stability. Furthermore, soil improvement in the planting area often only emphasizes fertilization, neglecting the need for soil structure stability and erosion resistance. Under the influence of slope erosion pressure and water fluctuations, it is difficult to simultaneously improve root zone water and soil stability, thus restricting the stable production capacity and ecological benefits of Camellia oleifera forests in hilly areas.

[0003] Therefore, existing technologies have shortcomings and need to be improved. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a soil and water conservation method for camellia oleifera forests in hilly areas that can effectively mitigate slope erosion, improve rainwater utilization efficiency, and enhance root zone soil stability.

[0005] To achieve this objective, the present invention adopts the following technical solution: a method for soil and water conservation in camellia oleifera forests suitable for hilly areas, comprising the following steps: S1. Steps for dividing and preparing woodland in hilly areas: Select camellia oleifera forest land in hilly areas with a slope of 10-25°, and divide the forest land into slope buffer zone, slope cultivation area and slope water catchment area according to the slope position; In the slope cultivation area, strip land preparation is carried out along the contour line direction. The strip land preparation adopts the method of alternating discontinuous terrace strips and undisturbed soil strips. The width of the terrace strips is 1.8-2.5m, and the undisturbed soil strips are retained between adjacent terrace strips. The width of the undisturbed soil strips is 0.4-0.7m. S2. Ladder stabilization and corrosion reduction structural treatment steps: A soil stabilization structure is set on the water-facing side of each ladder. The soil stabilization structure includes a low retaining wall formed by compacting the original soil, with a height of 15-25cm. A permeable buffer layer composed of a mixture of crushed stone and coarse sand is laid on the water-facing side of the retaining wall, wherein the mass ratio of crushed stone to coarse sand is 2-4:1 and the thickness is 6-12cm. By combining retaining walls with permeable buffer layers, the slope runoff is slowed down, diverted, and infiltrated at the terraces, reducing the risk of sediment moving downstream with the water. S3. Steps for treating water collection and slow-release ditches within the ladder belt: Water collection and slow-release ditches are set up near the inner side of each ladder. The water collection and slow-release ditches are arranged along the contour line, with a width of 30-45cm and a depth of 25-40cm. Organic filler material, such as chopped straw, decomposed branches or rice husks, is filled into the bottom of the water collection and slow release ditch and mixed with the topsoil to form a permeable matrix with a porous structure. The permeable matrix is ​​used to temporarily store runoff during rainfall and slowly release water to the lower soil layers after rainfall to avoid concentrated outflow of runoff in a short period of time. S4. Steps for combined soil and water conservation treatment in slope cultivation areas: In the planting holes of Camellia oleifera in the slope cultivation area, a soil-retaining and water-retaining composite layer is set up in a ring trench application method; the soil-retaining and water-retaining composite layer is formed by a mixture of decomposed organic fertilizer, biochar and fine soil, wherein the mass ratio of decomposed organic fertilizer, biochar and fine soil is 100-120:5-8:30-50. The mixture is applied into a circular trench with a depth of 20-30cm and backfilled and compacted to form a stable soil with enhanced water retention capacity in the root zone of the camellia oleifera. S5. Steps for water collection, sedimentation, and reuse at the toe of the slope: A sedimentation tank is set up in the catchment area at the foot of the slope. The sedimentation tank has a depth of 0.6-1.2m and the bottom of the tank is covered with a layer of crushed stone with a thickness of 10-20cm. Sedimentation basins are used to intercept sediment carried by slope runoff, allowing the water to clarify and then be reused through pipelines for supplementary irrigation of camellia oleifera forests, thereby reducing soil erosion and improving water resource utilization.

[0006] The above technical solution also includes a slope vegetation soil stabilization step: Plant ground cover plants that are resistant to trampling and have well-developed fibrous roots in the original soil strip area between the terraces. The ground cover plants are one or more of Bahia grass, Bermuda grass, or white clover. Ground cover plants are planted in strips, with strip widths of 0.5-1.0m and strip spacing of 0.6-1.2m. The root systems of ground cover plants reinforce the topsoil to inhibit slope erosion.

[0007] Using the above technical solution, ground cover plants are cut during the dry season, and the cut vegetation residues are used to cover the slope in situ to reduce soil moisture evaporation and enhance the surface's resistance to erosion.

[0008] Using the above technical solution, in step S3, the volume ratio of organic filler in the permeable matrix is ​​20-40%.

[0009] Using the above technical solution, in step S4, the biochar has a particle size of 2-10 mm and is used to form a stable porous structure in the soil to enhance the root zone's water retention capacity.

[0010] Using the above technical solution, the coverage rate of the ground cover plants is controlled at 60-85% to balance the soil and water conservation effect with the aeration needs of the Camellia oleifera root system.

[0011] Using the above technical solution, in step S4, the soil and water conservation composite layer is filled in a layered structure in the annular trench, consisting of a fine soil layer, a biochar mixed layer and a decomposed organic fertilizer layer from bottom to top, wherein the biochar mixed layer is located in the middle area 10-20 cm from the ground surface.

[0012] Using the above technical solution, the decomposed organic fertilizer is pre-wetted before being mixed with biochar and fine soil, so that its moisture content is controlled at 30-45% to enhance its binding ability with the surrounding soil particles.

[0013] Compared with the prior art, the present invention has the following beneficial effects: This invention effectively weakens the continuous accumulation and erosion capacity of slope runoff by dividing and preparing forest land in hilly areas and setting intermittent terraces and undisturbed soil strips along contour lines in the slope cultivation area, thereby improving the overall stability of the slope. Combined with the soil stabilization structure and permeable buffer layer on the water-facing side of the terraces, the runoff is slowed down, diverted, and infiltrated at the terraces, reducing the risk of sediment transport from the source. Water collection and slow-release ditches are set up on the inner side of the terraces and filled with organic fillers to form a permeable matrix, which can retain water during rainfall and slowly release and infiltrate after rain, improving the water conditions of the slope and root zone. A soil-retaining and water-retaining composite layer is set up in the Camellia oleifera planting hole through a ring trench, and combined with biochar, layered filling, and pre-wetting treatment with decomposed organic fertilizer, the stability of the root zone soil structure and water holding capacity can be enhanced. This invention can effectively control soil and water loss in Camellia oleifera forests in hilly areas and significantly improve the water use efficiency of hilly areas without large-scale hard engineering. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Furthermore, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., described below refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the technical features involved in the various embodiments of the invention can be combined with each other as long as they do not conflict with each other.

[0015] This invention provides a method for soil and water conservation in camellia oleifera forests in hilly areas, comprising the following steps: S1. Steps for dividing and preparing woodland in hilly areas: Select camellia oleifera forest land in hilly areas with a slope of 10-25°. Divide the forest land into a buffer zone on the slope, a cultivation area on the slope, and a water catchment area at the foot of the slope according to the slope position. In the cultivation area on the slope, strip land preparation is carried out along the contour line. The strip land preparation adopts the method of alternating discontinuous terrace strips and original soil strips. The width of the terrace strip is 1.8-2.5m. The original soil strips that have not been turned over are retained between adjacent terrace strips. The width of the original soil strips is 0.4-0.7m. This design avoids the continuous accumulation and accelerated discharge of surface runoff across the entire slope. By spatially zoning and controlling the direction of operations, the erosive effect of water flow on the slope soil is weakened. Setting up stepped zones along contour lines can effectively cut off the slope-to-slope runoff channels, allowing rainwater to remain on the slope and gradually infiltrate into the soil. The intermittent layout and retention of a certain width of undisturbed soil strips can help maintain the stability of the original soil structure on the slope and prevent the formation of continuous disturbance zones after land preparation. Thus, while meeting the needs of camellia cultivation operations, it can also improve the overall erosion resistance and soil stability of the slope.

[0016] S2. Ladder stabilization and corrosion reduction structural treatment steps: A soil stabilization structure is installed on the water-facing side of each terrace. This structure includes a low retaining wall formed by compacted original soil, with a height of 15-25 cm. A permeable buffer layer, composed of a mixture of crushed stone and coarse sand with a mass ratio of 2-4:1 and a thickness of 6-12 cm, is laid on the water-facing side of the retaining wall. This combination of the retaining wall and the permeable buffer layer slows, diverts, and infiltrates the slope runoff at the terraces, reducing the risk of sediment transport downstream. The low retaining wall, by creating a certain height difference, can reduce... The weak runoff's scouring energy prevents sediment from flowing directly across the embankment, while compacting the original soil improves the embankment's resistance to scouring and collapse. Setting up a crushed stone and coarse sand permeable buffer layer in front of the retaining embankment utilizes its large porosity and surface roughness to diffuse and slow down the water flow before it enters the embankment, reducing the frontal impact on the embankment and promoting the conversion of water from "surface flow" to "infiltration." This achieves erosion reduction of runoff, sediment retention, and soil moisture replenishment without the use of hard engineering, thereby reducing the risk of sediment moving downstream with the water.

[0017] S3. Steps for treating water collection and slow-release ditches within the ladder belt: Water collection and slow-release ditches are constructed near the inner side of each terrace. These ditches are laid along contour lines, with a width of 30-45 cm and a depth of 25-40 cm. Organic filler, consisting of chopped straw, decomposed branches, or rice husks, is placed at the bottom of the ditches and mixed with the topsoil to form a porous, permeable substrate. This substrate temporarily stores runoff during rainfall and slowly releases water into the lower soil layers after rainfall, preventing concentrated outflow of runoff in a short period. The ditches, located on the inner side of the terraces, collect runoff on-site after it is weakened by the terraces, preventing direct outflow. The organic filler at the bottom, mixed with the soil, forms a loose, porous structure, which increases short-term water storage capacity, reduces water flow velocity, and minimizes mud erosion within the ditches. Furthermore, the water absorption and slow-release properties of the organic filler allow the stored water to gradually infiltrate into the root zone after rainfall, thus achieving peak flow reduction, minimizing concentrated outflow, and simultaneously improving the water retention capacity of the slope soil.

[0018] S4. Steps for combined soil and water conservation treatment in slope cultivation areas: In the planting holes of Camellia oleifera on slopes, a soil-retaining and water-retaining composite layer is set up using a circular trench application method. This composite layer is formed by mixing well-rotted organic fertilizer, biochar, and fine soil, with a mass ratio of 100-120:5-8:30-50. The mixture is applied into a circular trench 20-30 cm deep and then backfilled and compacted. This creates a stable soil structure with enhanced water retention in the root zone of the Camellia oleifera. The circular trench application creates a continuous improvement zone around the root zone, avoiding localized loosening caused by spot application. It can be dispersed or migrated with runoff; well-rotted organic fertilizer can provide organic matter and enhance soil cohesion and water and fertilizer retention capacity; the porous structure of biochar can improve infiltration and water storage space; fine soil is used for filling and transition to ensure that the mixed layer is closely combined with the original soil; placing the mixture at a depth of 20-30cm and backfilling and compacting can reduce rainwater erosion disturbance without affecting surface operations, forming a more stable rhizosphere soil, thereby improving water retention under rainfall conditions and water supply capacity during dry seasons, and reducing the risk of soil loosening, water loss and fertilizer loss in planting holes under slope conditions.

[0019] S5. Steps for water collection, sedimentation, and reuse at the toe of the slope: A sedimentation basin is set up in the catchment area at the foot of the slope. The sedimentation basin is 0.6-1.2m deep and the bottom of the basin is covered with a layer of gravel with a thickness of 10-20cm. The sedimentation basin is used to intercept the sediment carried by the slope runoff. After the water is clarified, it is reused in the camellia oleifera forest for supplementary irrigation through pipelines. In this way, the rainy season runoff that was originally discharged can be transformed into a usable water source, which not only reduces the loss of soil and water on the slope, but also improves the water security capacity during the dry season and the overall water resource utilization efficiency.

[0020] Furthermore, it also includes a slope vegetation soil stabilization step: planting trampling-resistant, well-developed fibrous ground cover plants in the original soil strip area between the terraces. The ground cover plants are one or more of Bahia grass, Bermuda grass, or white clover. The ground cover plants are planted in strips with a strip width of 0.5-1.0m and a strip spacing of 0.6-1.2m. The root system of the ground cover plants is used to reinforce the surface soil to inhibit slope erosion. The reason for planting trampling-resistant, fibrous-rooted ground cover plants such as Bahia grass, Bermuda grass, or white clover in the original soil areas between the terraces, and for using strip planting with controlled strip width and spacing, is to use plant roots to firmly stabilize the topsoil and inhibit rainwater erosion without disturbing the soil over a large area. Strip planting can form continuous interception and deceleration zones on the slope, weakening the flow velocity and sand-carrying capacity of runoff, while avoiding excessive competition for water and fertilizer with camellia due to full coverage. It balances soil and water conservation with the growth needs of camellia, thus more stably inhibiting slope erosion and improving the overall soil conservation capacity in conjunction with the terrace structure.

[0021] Furthermore, ground cover plants are mowed during the dry season, and the resulting vegetation residue is used to cover the slope in situ to reduce soil moisture evaporation and enhance the surface's resistance to erosion. Mowing reduces the transpiration water consumption of ground cover plants during the dry season, lessening water competition between them and camellia oleifera. The in-situ vegetation residue forms a cover layer on the soil surface, blocking sunlight and wind, and slowing down soil moisture evaporation. At the same time, this cover layer can buffer the impact of raindrops at the beginning of rainfall, reducing the risk of surface soil being broken up and washed away by water. Thus, under the alternating conditions of dry and rainy seasons, it enhances the water retention capacity and erosion resistance of the slope surface.

[0022] Furthermore, in step S3, the volume ratio of organic filler in the permeable matrix is ​​20-40%, thus achieving a balance between water storage capacity and structural stability. When the proportion of organic filler is 20-40%, it can provide sufficient temporary storage space through its water absorption and porous structure, allowing rainwater runoff to be effectively retained and slowly released in the ditch, without causing a decrease in the overall strength of the matrix or collapse under long-term wet conditions due to an excessively high filler ratio.

[0023] Furthermore, in step S4, the biochar has a particle size of 2-10 mm and is used to form a stable porous structure in the soil to enhance the root zone's water retention capacity.

[0024] Furthermore, the ground cover plant coverage is controlled at 60-85%. This allows the ground cover plants to provide continuous protection to the slope through leaf shading and root network, effectively reducing direct impact from raindrops and surface runoff erosion, and lowering the risk of topsoil loss. At the same time, it avoids excessive moisture on the slope due to overly dense coverage, which could affect soil aeration or intensify competition for water and nutrients between the ground cover plants and the Camellia oleifera root system. Thus, while ensuring soil stabilization and erosion reduction, it also maintains the soil environment required for normal respiration and growth of the Camellia oleifera root system, balancing soil and water conservation with the aeration needs of the Camellia oleifera root system.

[0025] Furthermore, in step S4, the soil-retaining and water-retaining composite layer is applied in a layered structure within the annular trench, consisting of a fine soil layer, a biochar mixed layer, and a decomposed organic fertilizer layer from bottom to top. The biochar mixed layer is located in the middle area 10-20cm below the surface. The middle biochar mixed layer is located within the main activity depth range of the camellia root system, which can form a stable pore structure in this layer to effectively retain and slowly release infiltrated water, thereby improving the water holding capacity of the root zone. The upper decomposed organic fertilizer layer is more conducive to improving the fertility and structure of the surface soil and participates in the initial water absorption and buffering effect during rainfall.

[0026] Furthermore, the decomposed organic fertilizer is pre-wetted before being mixed with biochar and fine soil to control its moisture content at 30-45%. The moderately moist decomposed organic fertilizer is more likely to combine evenly with fine soil and biochar during mixing and backfilling, reducing stratification, agglomeration, or floating phenomena that occur under dry conditions, thereby preventing it from being carried away by water flow under rainfall conditions. At the same time, the pre-wetting treatment allows the organic fertilizer particles to quickly form close contact with the surrounding soil after being put into the soil, improving its fixation and continuous water retention capacity in the root zone, and enhancing its binding ability with the surrounding soil particles.

[0027] Example 1 Embodiment 1 of the present invention provides a method for soil and water conservation in camellia oleifera forests in hilly areas, comprising the following steps: S1. Steps for dividing and preparing woodland in hilly areas: Select camellia oleifera forest land in a hilly area with a slope of 10°, and divide the forest land into a buffer zone on the slope, a cultivation area on the slope and a water catchment area at the foot of the slope according to the slope position; In the slope cultivation area, strip land preparation is carried out along the contour line direction. The strip land preparation adopts the method of alternating intermittent terrace strips and undisturbed soil strips. The width of the terrace strip is 1.8m, and the undisturbed soil strip is retained between adjacent terrace strips. The width of the undisturbed soil strip is 0.4m. It also includes slope vegetation soil stabilization steps: In the original soil strip area between the terraces, a ground cover plant with strong roots that is resistant to trampling is planted. The ground cover plant is Bahia grass. The ground cover plant is planted in strips with a strip width of 0.5m and a strip spacing of 0.6m. The root system of the ground cover plant reinforces the topsoil to inhibit slope erosion. The ground cover vegetation coverage is controlled at 60% to balance soil and water conservation with the aeration needs of the camellia root system. During the dry season, ground cover plants are cut and the cut vegetation residues are used to cover the slope in place to reduce soil moisture evaporation and enhance the surface's resistance to erosion. S2. Ladder stabilization and corrosion reduction structural treatment steps: A soil stabilization structure is installed on the water-facing side of each ladder. The soil stabilization structure includes a low retaining wall formed by compacting the original soil, with a height of 15cm. A permeable buffer layer made of a mixture of crushed stone and coarse sand is laid on the water-facing side of the retaining wall, with a mass ratio of crushed stone to coarse sand of 2:1 and a thickness of 6cm. By combining retaining walls with permeable buffer layers, the slope runoff is slowed down, diverted, and infiltrated at the terraces, reducing the risk of sediment moving downstream with the water. S3. Steps for treating water collection and slow-release ditches within the ladder belt: Water collection and slow-release ditches are set up near the inner side of each ladder. The water collection and slow-release ditches are arranged along the contour line, with a width of 30cm and a depth of 25cm. Organic filler material, consisting of chopped straw, is placed at the bottom of the water collection and slow-release ditch and mixed with the topsoil to form a porous permeable matrix. The organic filler material accounts for 20% of the volume of the permeable matrix. The permeable matrix is ​​used to temporarily store runoff during rainfall and slowly release water to the lower soil layers after rainfall to avoid concentrated outflow of runoff in a short period of time. S4. Steps for combined soil and water conservation treatment in slope cultivation areas: In the planting holes of Camellia oleifera in the slope cultivation area, a soil-retaining and water-retaining composite layer is set up in a ring trench. The soil-retaining and water-retaining composite layer is formed by mixing well-rotted organic fertilizer, biochar and fine soil. The mass ratio of well-rotted organic fertilizer, biochar and fine soil is 100:5:30. The biochar has a particle size of 10mm and is used to form a stable pore structure in the soil to enhance the water retention capacity of the root zone. The mixture is applied into a 20cm deep circular trench and backfilled and compacted to form a stable soil with enhanced water retention capacity in the root zone of the camellia oleifera. The soil and water conservation composite layer is filled in a layered structure within the ring trench, consisting of a fine soil layer, a biochar mixed layer, and a decomposed organic fertilizer layer from bottom to top. The biochar mixed layer is located in the middle area 10cm from the surface. Before being mixed with the biochar and fine soil, the decomposed organic fertilizer is pre-wetted to control its moisture content at 30% in order to enhance its binding ability with the surrounding soil particles. S5. Steps for water collection, sedimentation, and reuse at the toe of the slope: A sedimentation tank with a depth of 0.6m is set up in the catchment area at the foot of the slope. The bottom of the sedimentation tank is covered with a layer of crushed stone with a thickness of 10cm. Sedimentation basins are used to intercept sediment carried by slope runoff, allowing the water to clarify and then be reused through pipelines for supplementary irrigation of camellia oleifera forests, thereby reducing soil erosion and improving water resource utilization.

[0028] Example 2 Embodiment 2 of the present invention provides a method for soil and water conservation in camellia oleifera forests in hilly areas, comprising the following steps: S1. Steps for dividing and preparing woodland in hilly areas: Select camellia oleifera forest land in a hilly area with a slope of 25°, and divide the forest land into a buffer zone on the slope, a cultivation area on the slope and a water catchment area at the foot of the slope according to the slope position; In the slope cultivation area, strip land preparation is carried out along the contour line direction. The strip land preparation adopts the method of alternating intermittent terrace strips and undisturbed soil strips. The width of the terrace strip is 2.5m, and the undisturbed soil strip is retained between adjacent terrace strips. The width of the undisturbed soil strip is 0.7m. It also includes slope vegetation soil stabilization steps: Plant ground cover plants that are resistant to trampling and have well-developed fibrous roots in the original soil strip area between the terraces. The ground cover plants are Bermuda grass. Ground cover plants are planted in strips, with strips 1.0m wide and 1.2m apart; the root system of the ground cover plants reinforces the topsoil to inhibit slope erosion. The ground cover vegetation coverage is controlled at 85% to balance soil and water conservation with the aeration needs of the camellia root system. During the dry season, ground cover plants are cut and the cut vegetation residues are used to cover the slope in place to reduce soil moisture evaporation and enhance the surface's resistance to erosion. S2. Ladder stabilization and corrosion reduction structural treatment steps: A soil stabilization structure is installed on the water-facing side of each ladder. The soil stabilization structure includes a low retaining wall formed by compacting the original soil, with a height of 25cm. A permeable buffer layer composed of a mixture of crushed stone and coarse sand is laid on the water-facing side of the retaining wall, with a mass ratio of crushed stone to coarse sand of 4:1 and a thickness of 12cm. By combining retaining walls with permeable buffer layers, the slope runoff is slowed down, diverted, and infiltrated at the terraces, reducing the risk of sediment moving downstream with the water. S3. Steps for treating water collection and slow-release ditches within the ladder belt: Water collection and slow-release ditches are set up near the inner side of each ladder. The water collection and slow-release ditches are arranged along the contour line, with a width of 45cm and a depth of 40cm. Organic filler material, namely rice husks, is filled into the bottom of the water collection and slow-release ditch and mixed with the topsoil to form a porous permeable matrix. The volume ratio of the organic filler material in the permeable matrix is ​​40%. The permeable matrix is ​​used to temporarily store runoff during rainfall and slowly release water to the lower soil layers after rainfall to avoid concentrated outflow of runoff in a short period of time. S4. Steps for combined soil and water conservation treatment in slope cultivation areas: In the planting holes of Camellia oleifera in the slope cultivation area, a soil-retaining and water-retaining composite layer is set up in a ring trench. The soil-retaining and water-retaining composite layer is formed by mixing well-rotted organic fertilizer, biochar and fine soil. The mass ratio of well-rotted organic fertilizer, biochar and fine soil is 120:8:50. The biochar has a particle size of 6mm and is used to form a stable pore structure in the soil to enhance the water retention capacity of the root zone. The mixture is applied into a 30cm deep circular trench and backfilled and compacted to form a stable soil with enhanced water retention capacity in the root zone of the camellia oleifera. The soil and water conservation composite layer is filled in a layered structure within the ring trench, consisting of a fine soil layer, a biochar mixed layer, and a decomposed organic fertilizer layer from bottom to top. The biochar mixed layer is located in the middle area 20 cm below the surface. Before being mixed with the biochar and fine soil, the decomposed organic fertilizer is pre-wetted to control its moisture content at 45%, thereby enhancing its ability to bind with the surrounding soil particles. S5. Steps for water collection, sedimentation, and reuse at the toe of the slope: A sedimentation tank with a depth of 1.2m is set up in the catchment area at the foot of the slope. The bottom of the sedimentation tank is covered with a layer of crushed stone with a thickness of 20cm. Sedimentation basins are used to intercept sediment carried by slope runoff, allowing the water to clarify and then be reused through pipelines for supplementary irrigation of camellia oleifera forests, thereby reducing soil erosion and improving water resource utilization.

[0029] Comparative Example 1 The difference between Comparative Example 1, which describes a soil and water conservation method for camellia oleifera forests in hilly areas, and Example 1 is that continuous terraced land preparation is carried out along contour lines in the slope cultivation area, without retaining the original soil strips, and the terraces are interconnected.

[0030] Comparative Example 2 The difference between Comparative Example 2, which describes a soil and water conservation method for camellia oleifera forests in hilly areas, and Example 1 is that only a low retaining wall formed by compacted original soil is set up on the water-facing side of each terrace, and no permeable buffer layer formed by gravel and coarse sand is laid on the water-facing side of the retaining wall.

[0031] Comparative Example 3 The difference between Comparative Example 3, which describes a soil and water conservation method for camellia oleifera forests in hilly areas, and Example 1 is that a water collection ditch is opened on the inner side of the terrace, but the bottom of the ditch is not filled with organic fillers such as chopped straw, decomposed branches, or rice husks; it is just a bare soil ditch.

[0032] Comparative Example 4 The difference between Comparative Example 4, which describes a soil and water conservation method for camellia oleifera forests in hilly areas, and Example 1 is that only well-rotted organic fertilizer is applied as base fertilizer in the planting hole, and no soil and water conservation composite layer consisting of well-rotted organic fertilizer, biochar, and fine soil is set up.

[0033] Comparative Example 5 The difference between Comparative Example 5, which describes a soil and water conservation method for camellia oleifera forests in hilly areas, and Example 1 is that the ground cover plants are planted in a full-coverage manner, without strip planting or control of the coverage rate.

[0034] The following experiments were conducted on Examples 1-2 and Comparative Examples 1-5 to verify or understand their performance effects. The water and soil conservation performance comparison table of Examples 1-2 and Comparative Examples 1-5 is shown below.

[0035] Table 1. Comparison of Soil and Water Conservation Performance of Various Examples and Comparative Examples According to Table 1 above: As can be seen from the comparison between Example 1 and Comparative Example 1, the intermittent terraced strip and undisturbed soil strip alternating structure arranged along the contour line in the slope cultivation area can effectively weaken the continuous accumulation and accelerated discharge trend of slope runoff compared with the continuous terraced strip land preparation method in Comparative Example 1, thereby reducing the risk of slope erosion and improving the overall slope structure stability. The comparison results between Example 1 and Comparative Example 2 show that the combined structure of setting both a low retaining wall and a permeable buffer layer on the water-facing side of the stepped strip can more effectively reduce the runoff scouring intensity and promote water infiltration compared to setting only a retaining wall, thus significantly improving the erosion reduction and water retention effects. As can be seen from the comparison between Example 1 and Comparative Example 3, introducing organic filler into the water collection and slow release ditch inside the ladder belt and forming a permeable matrix with a porous structure can effectively store and slow release rainwater runoff. Compared with the water collection ditch structure without organic filler, it is more conducive to reducing concentrated discharge and improving the soil moisture conditions on the slope. Furthermore, the comparison between Example 1 and Comparative Example 4 shows that the use of a soil-retaining and water-retaining composite layer structure composed of decomposed organic fertilizer, biochar and fine soil in the Camellia oleifera planting area can effectively improve the stability and water retention capacity of the root zone soil. Compared with the method of applying only a single organic fertilizer, it is more conducive to maintaining the structural stability of the planting hole under rainfall and dry season conditions. Meanwhile, the comparison results between Example 1 and Comparative Example 5 show that by adopting strip planting for slope ground cover plants and reasonably controlling the coverage rate, the effect of slope soil stabilization and erosion reduction can be enhanced while avoiding adverse effects on the growth of Camellia oleifera, thereby achieving a balance between soil and water conservation and the growth needs of Camellia oleifera.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for soil and water conservation in camellia oleifera forests in hilly areas, characterized in that, Includes the following steps: S1. Steps for dividing and preparing woodland in hilly areas: Select camellia oleifera forest land in hilly areas with a slope of 10-25°, and divide the forest land into slope buffer zone, slope cultivation area and slope water catchment area according to the slope position; In the slope cultivation area, strip land preparation is carried out along the contour line direction. The strip land preparation adopts the method of alternating discontinuous terrace strips and undisturbed soil strips. The width of the terrace strips is 1.8-2.5m, and the undisturbed soil strips are retained between adjacent terrace strips. The width of the undisturbed soil strips is 0.4-0.7m. S2. Ladder stabilization and corrosion reduction structural treatment steps: A soil stabilization structure is set on the water-facing side of each ladder. The soil stabilization structure includes a low retaining wall formed by compacting the original soil, with a height of 15-25cm. A permeable buffer layer composed of a mixture of crushed stone and coarse sand is laid on the water-facing side of the retaining wall, wherein the mass ratio of crushed stone to coarse sand is 2-4:1 and the thickness is 6-12cm. By combining retaining walls with permeable buffer layers, the slope runoff is slowed down, diverted, and infiltrated at the terraces, reducing the risk of sediment moving downstream with the water. S3. Steps for treating water collection and slow-release ditches within the ladder belt: Water collection and slow-release ditches are set up near the inner side of each ladder. The water collection and slow-release ditches are arranged along the contour line, with a width of 30-45cm and a depth of 25-40cm. Organic filler material, such as chopped straw, decomposed branches or rice husks, is filled into the bottom of the water collection and slow release ditch and mixed with the topsoil to form a permeable matrix with a porous structure. The permeable matrix is ​​used to temporarily store runoff during rainfall and slowly release water to the lower soil layers after rainfall to avoid concentrated outflow of runoff in a short period of time. S4. Steps for combined soil and water conservation treatment in slope cultivation areas: In the planting holes of Camellia oleifera in the slope cultivation area, a soil-retaining and water-retaining composite layer is set up in a ring trench application method; the soil-retaining and water-retaining composite layer is formed by a mixture of decomposed organic fertilizer, biochar and fine soil, wherein the mass ratio of decomposed organic fertilizer, biochar and fine soil is 100-120:5-8:30-50. The mixture forming the soil-retaining and water-retaining composite layer is applied into a ring trench with a depth of 20-30cm and backfilled and compacted to form a stable soil with enhanced water retention capacity in the root activity zone of Camellia oleifera. S5. Steps for water collection, sedimentation, and reuse at the toe of the slope: A sedimentation tank is set up in the catchment area at the foot of the slope. The sedimentation tank has a depth of 0.6-1.2m and the bottom of the tank is covered with a layer of crushed stone with a thickness of 10-20cm. Sedimentation basins are used to intercept sediment carried by slope runoff, allowing the water to clarify and then be reused through pipelines for supplementary irrigation of camellia oleifera forests, thereby reducing soil erosion and improving water resource utilization.

2. The method for soil and water conservation in camellia oleifera forests in hilly areas according to claim 1, characterized in that, It also includes slope vegetation soil stabilization steps: Plant ground cover plants that are resistant to trampling and have well-developed fibrous roots in the original soil strip area between the terraces. The ground cover plants are one or more of Bahia grass, Bermuda grass, or white clover. Ground cover plants are planted in strips, with strip widths of 0.5-1.0m and strip spacing of 0.6-1.2m. The root systems of ground cover plants reinforce the topsoil to inhibit slope erosion.

3. The method for soil and water conservation in camellia oleifera forests in hilly areas according to claim 2, characterized in that, During the dry season, ground cover plants are cut and the remaining vegetation is used to cover the slope to reduce soil moisture evaporation and enhance the surface's resistance to erosion.

4. The method for soil and water conservation in camellia oleifera forests in hilly areas according to claim 1, characterized in that, In step S3, the volume percentage of organic filler in the permeable matrix is ​​20-40%.

5. The method for soil and water conservation in camellia oleifera forests in hilly areas according to claim 1, characterized in that, In step S4, the biochar has a particle size of 2-10 mm and is used to form a stable porous structure in the soil to enhance the root zone's water retention capacity.

6. The method for soil and water conservation in camellia oleifera forests in hilly areas according to claim 2, characterized in that, The ground cover vegetation coverage is controlled at 60-85% to balance soil and water conservation with the aeration needs of the camellia root system.

7. The method for soil and water conservation in camellia oleifera forests in hilly areas according to claim 1, characterized in that, In step S4, the soil and water conservation composite layer is applied in a layered structure within the annular trench, consisting of a fine soil layer, a biochar mixed layer, and a decomposed organic fertilizer layer from bottom to top, wherein the biochar mixed layer is located in the middle area 10-20 cm below the surface.

8. The method for soil and water conservation in camellia oleifera forests in hilly areas according to claim 1, characterized in that, Before being mixed with biochar and fine soil, the decomposed organic fertilizer is pre-wetted to control its moisture content at 30-45% in order to enhance its binding ability with the surrounding soil particles.

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