What specific contents does the planning of a walnut orchard include?
Because walnut has a wide range of adaptation, the selection of the orchard site is not very strict, and the planning of the orchard is also relatively extensive. As long as scientific planning is carried out according to the topography and climate characteristics of a certain region, the unfavorable factors of establishing the orchard can be weakened or eliminated, which is beneficial to future production and operation. Before establishing the orchard, a detailed investigation should be conducted into the basic conditions of the orchard site, including the socioeconomic situation, walnut production situation, climatic conditions, topographic and soil conditions, and water conservancy conditions, so as to provide a basis for the planning and design of the orchard. For larger orchard establishment areas or orchard establishment on mountain land, surveying work for area, topography, and soil and water conservation projects should also be carried out. After surveying flat land, draw a plan showing prominent topographic changes and ground features; for mountain land, contour surveying should be carried out, and a 1:1000 topographic map should be drawn, with contour density and elevation difference shown on the topographic map, and land use status, soil distribution maps, water conservancy maps, etc. drawn based on the topography for planning use. The specific orchard planning contents mainly include the following aspects:
1. Division of production plots The division of orchard plots is very important for future management. The division of plots must meet the following requirements: first, the climate and light conditions within the plot are roughly consistent; second, it is convenient to prevent soil erosion within the orchard; third, it is convenient to prevent wind damage within the orchard; fourth, it is convenient for transportation within the orchard.
For hilly and mountainous land, the whole orchard should mainly be divided into several units according to changes in topography and terrain. In specific division, it must be integrated with the unified planning of orchard infrastructure such as orchard roads, drainage and irrigation systems, and shelterbelts. Within the same plot, the soil type, slope aspect, and climatic conditions should be roughly similar, and its area size and shape should be adapted to the site conditions and should not be artificially divided. When the mountainous terrain is complex, one slope can be treated as one plot.
The shape and size of plots should vary according to topography and terrain. The long side of a plot on mountain land should be parallel to the contour lines. When the slope surface is large, plots should be arranged as upper, middle, and lower plots according to horizontal position. In mountainous and hilly areas with relatively poor natural conditions, a plot area of 30-45 mu should be used as one plot, and a plot should not cross a watershed or a large ditch; in plain areas suitable for planting, the plot area should be 50-100 mu, and a rectangular shape is preferred.
2. Road system Correct and reasonable road system planning can facilitate management, reduce labor intensity, and improve work efficiency. For the convenience of walnut orchard management and transportation, roads of different widths should be set up according to needs. Roads at all levels should be planned as a whole and coordinated with plots, shelterbelts, drainage and irrigation systems, etc. Generally, the road system of large and medium-sized walnut orchards consists of three levels: main roads, branch roads, and operation roads. Main roads are required to be 4-5 m wide, run through the whole orchard, and be able to allow large trucks to pass; branch roads are roads connecting the main road to the operation areas, generally 3-4 m wide, and able to allow tractors to pass; operation roads are the main routes for production activities within the production areas, required to be 2-3 m wide, and should be able to allow small cars and agricultural machinery to pass. In small walnut orchards, in order to reduce non-production land, main roads and small roads may be omitted, and only branch roads may be set up.
In mountainous and hilly areas, main roads are required to be built around the mountain, with a width of 3-5 m. Branch roads are set between plots, with a width of 2-3 m, and should be able to allow horse carts, small cars, and agricultural machinery to pass. Operation roads are set within or between plots, 1-2 m wide, mainly used for farming operations.
When designing roads in mountainous areas, they can incline upward along the slope, or go around the mountain along the cross slope in a zigzag bend. Roads along the slope should be set on the watershed line and not on the water collection line, so as to avoid being washed away by water. Generally, drainage ditches should be built on the inner side of the road, and the road surface should be inclined inward to extend its service life.
3. Drainage and irrigation system The irrigation system is one of the important measures to ensure high and stable yields in walnut orchards. In flatland walnut orchards, surface irrigation channels include three levels: main canals, branch canals, and lateral canals. Main canals lead water to the orchard and run through the whole orchard. Branch canals lead water from the main canals to the orchard plots. Lateral canals lead water from the branch canals to the spaces between walnut rows and between plants. In the planning and design of irrigation channels, the orchard's topographic conditions and the height of the water source position should be considered, and they should be combined with roads, shelterbelts, and drainage systems. Channels should have a longitudinal gradient to reduce scouring and silting. Generally, the gradient of main canals is 1/1000, and the gradient of branch canals is 1/500. If the gradient is too small, water flow is not smooth; if the gradient is too large, scouring is severe.
For orchards on hilly and mountainous land, the design of water storage, water conveyance, and irrigation networks should be considered first. Where water sources can be used, sites should be selected to build small reservoirs or water storage ponds for irrigation. Pipeline irrigation is most suitable for orchards on hilly and mountainous land, adopting water-saving irrigation measures such as gravity irrigation, drip irrigation, and subsurface irrigation.