GB/T 16453.1-2008Technical specification for comprehensive control of soil and water conservation - Technique for erosion control of slope land (English PDF)

3.1 Soil and water conservation tillage

3.1.1 Soil and water conservation tillage is a tillage method designed to enhance soil erosion resistance, conserve soil and water, mitigate soil erosion, and boost crop yields on slope land. It involves implementing various measures such as altering microtopography, increasing ground plant cover, and enhancing soil infiltration based on agricultural practices carried out annually. And it can be classified into the following four types:

Type I, it involves altering microtopography for soil and water conservation, and mainly includes practices such as contour tillage, ridge and furrow planting, pot-hollowing (burrowing) planting, drought-resistant and high-yielding furrows, and contour furrows in fallow lands.

Type II, it involves increasing ground plant cover for soil and water conservation, and mainly includes practices such as grass and cropping rotation, intercropping, interplanting, strip intercropping, rational close planting, sowing green manure in fallow lands and so on.

Type III, which is a type of soil and water conservation tillage aimed at improving soil infiltration and enhancing soil erosion resistance, mainly involves practices like deep ploughing, subsoiling, increase organic manure fertilizer application, stubble sowing and so on.

Type IV, which is a type of soil and water conservation tillage aimed at reducing soil evaporation, mainly involves practices like plastic film mulching and straw mulching.

3.1.2 Before implementing soil and water conservation tillage, comprehensive planning shall be carried out at small watershed level to effectively manage slope land in its entirety. Various types of terraces shall be set up based on conditions such as different topography, soil quality, and rainfall, and then soil conservation tillage shall be carried out and small slope-specific storage and drainage works shall be constructed accordingly. For slope land with a gradient below 25° that has not been terraced, soil conservation tillage shall be adopted.

3.1.3

While adopting soil conservation tillage, small-scale slope-specific storage and drainage facilities shall be provided on the inner as well as outer sides of the upper part of the slope land to prevent external water from entering.

3.1.4

The specific practices and relevant specifications and dimensions of various soil conservation tillage have different adaptation conditions; thus, they shall be determined reasonably based on the varying topography, soil quality, rainfall, and agricultural practices in different regions, tailored to local conditions.

3.2 Terrace

3.2.1 Depending on the different ground gradients, terraces can be divided into steep slope terraces and gentle slope terraces. Depending on the different materials used for making the field ridges, terraces can be divided into earth ridge terraces, stone ridge terraces, and plant ridge terraces. Depending on the different sections of terraces, they can be divided into bench terraces, sloping terraces, interval terraces, and back-slope terraces (see Figure 1). Depending on the different purposes of terraces, they can be divided into dry crop terraces, rice terraces, orchard terraces, tea garden terraces, rubber plantation terraces, etc.

Figure 1 Schematic diagram for the sections of three types of terraces

3.2.2 Comprehensively plan the management of slope land by taking small watersheds as the unit. Then, determine applicable practices based on specific conditions, such as constructing terraces, adopting soil conservation tillage, or providing small slope-specific storage and drainage works. For areas to be developed as terraced areas, specific planning for terraces shall be carried out. Based on this, design and construction shall be carried out accordingly.

3.2.3 When the slopes above the terraces are slope lands or waste lands, small-scale slope-specific storage and drainage facilities shall be arranged to prevent surface runoff from entering the terraced area. Small-scale storage and drainage facilities shall also be arranged in terraced areas in southern China, so as to properly manage excess rainwater and ensure the safety of the terraces. The technical requirements for small-scale slope-specific storage and drainage facilities are as specified in GB/T 16453.4.

Generally, the criteria for safeguarding terraces against rainstorms shall be established against a 10-year maximum rainfall, lasting for a duration of 3 to 6 hours. In arid and semi-arid regions, the criteria may be established against a 20-year maximum rainfall, lasting for a duration of 3 to 6 hours. Depending on the rainfall characteristics of each region, locally prevalent short-duration, high-intensity rainfall events that are most likely to cause severe soil erosion and water loss shall be considered.