Walnut orchard selection

The selection of    walnut orchard is directly related to the success or failure of pollution-free walnut production and its economic benefits. To achieve the goal of early fruit, high quality, high yield, high efficiency and no pollution as far as possible, we should choose places with flat terrain, deep soil, fertile soil, leeward to the sun and convenient transportation. At the same time, the garden is required to have a good ecological ring with fresh air, pure water quality and no pollution, away from industrial and mining, mining and transportation lines that are easy to produce pollutants. Avoid planting walnut on the soil grown by willow and poplar to prevent the occurrence of root rot and avoid walnut continuous cropping for many years, which will greatly increase the density of root-knot nematodes and affect the growth and development of walnut; abandoned land due to the decline of soil fertility and production performance, do not choose stubble land and abandoned land.

   1. Requirements of climatic conditions in the founding land of walnut from the point of view of geographical distribution, most of the natural producing areas of walnut are relatively warm, and 30 °~ 40 °north latitude is the suitable cultivation area of walnut. As far as vertical distribution is concerned, walnut grows well in the area with an altitude of 700 to 1 300 meters. It can be planted in the areas where the frost-free period is more than 180days and the annual average temperature is 8-16 ℃. Walnut trees can withstand low temperatures of-20 ℃ during dormancy, and cold tolerance of some varieties can reach-30 °C. After sprouting in spring, the ability of cold tolerance decreases. If the temperature drops to-4 °C, the new shoots will be frozen, and the temperature in flowering and young fruit stage will be reduced to-2 °- 1 ℃, that is, the yield will be reduced by freezing, but it will not cause great damage to adult trees.

   walnut trees do not have strict requirements on atmospheric humidity, and their growth and fruit is still normal in a dry climate. Walnut growth and development is more sensitive to soil moisture, too drought and too wet are not conducive to walnut growth. When there is insufficient water in the seedling stage, the growth stops. In the fruiting period, under the condition of excessive drought, the growth of the tree is weak, the leaf is small and the fruit is small, which must be watered. A long sunny and dry climate can promote flowering and fruiting. Walnut in the case of poor drainage, long-term stagnant water, especially by pollution, will produce hypoxia, resulting in root rot, or even the death of the whole plant.

   walnut has strong adaptability to soil, whether in hills, mountains or Pingchuan, it can grow as long as the soil layer is thick and the drainage is good. Walnut trees grow better in the valley with loose soil and good drainage. Walnut trees grow well in neutral and slightly alkaline soil with groundwater level below 1.5m and pH of 7.08.2.

   2, the influence of topography the general requirements for the selection of walnut orchard site are leeward, sunny air circulation and abundant sunshine. The mountain area of our country accounts for more than 2 to 3 of the national land area, and walnuts are mostly cultivated on hillside land. The mountain area has the characteristics of good air circulation, sufficient sunshine and good drainage, but the mountain terrain is complex, the climate is changeable, the soil layer is thin, the fertilizer and water condition is poor, and the transportation is inconvenient, which brings some difficulties to the production and management of walnut. Therefore, when planting walnuts in mountainous areas, special attention should be paid to altitude, slope, slope aspect, slope shape and soil thickness, as well as walnut adaptation to temperature, light, water and other conditions. According to the difference of mountain topography, absolute height and relative height, the mountain can be divided into hilly zone, foothill zone, low mountain belt, middle mountain belt and high mountain belt. The slope of the mountain garden should be less than 20 °, such as the mountain is not undulating and the slope is relatively neat, especially in the mountainous area of southwest China, where the slope is more than 25 °can also be used properly.

Under the specific site conditions, the location and direction of the topography can affect the light, air temperature, soil and water conditions, and change with time. The walnut orchard had better be built on flat land and gentle slope, and the slope direction should be open to the sunny side. Judging from the existing distribution of walnuts, the places with plenty of water on both sides of the stream and riverbed are the best.

   3. The influence of slope direction on the selection of slope direction, in theory, sunny slope and semi-sunny slope are the best, but under the condition of sufficient light and no irrigation, walnut trees planted on semi-shady slope and shady slope are better than sunny slope and semi-sunny slope. Planting walnut trees in mountainous and hilly areas can produce high quality fruits because of the large temperature difference and good light conditions, which is beneficial to the production and accumulation of photosynthate. However, it will also produce some adverse ecological factors and affect the development of walnut.

The slope of    hills and mountains has a great influence on soil fertility and water condition. The larger the slope is, the more serious the erosion of Rain Water is and the more serious the nutrient leaching is, the poorer the soil is, the less water is, and the drier the soil is. Therefore, soil and water conservation projects must be planned in areas with large slopes. After comprehensive consideration of various ecological factors and preliminary determination of the garden site, the overall planning and design of the walnut orchard should be carried out, including garden regulation, main roads, drainage and irrigation system, establishment of shelterbelt, community division and variety collocation, etc.

   4, the influence of wind and sand and saline-alkali on sandy wasteland due to strong wind, large fluidity of sand and dust, and poor soil water storage capacity, so planting walnut on sandy wasteland should build protective forest as early as possible before the establishment of the garden, so as to achieve the purpose of preventing wind and fixing sand and improving the climatic environment of walnut orchard. Light saline-alkali land, through reasonable planning, improve the soil, set up drainage and irrigation system, and select suitable varieties for walnut production.