Correct use of Fertilizer for Fruit trees

The correct use of fertilizer in fruit trees is one of the key links in the production of pollution-free fruits. The correct use of fertilizer in fruit trees is one of the key links in the production of pollution-free fruits. The national agricultural industry standards promulgated and implemented by the Ministry of Agriculture last year also clearly stipulated the guidelines for the use of fertilizers for the production of green food (fruits), requiring that the principle of fertilization should be mainly organic fertilizers, supplemented by chemical fertilizers, to maintain or increase soil fertility and soil microbial activity, and at the same time, the fertilizers used should not adversely affect the orchard environment and fruit quality. Combined with the implementation of the standard and the demand for fertilizer in fruit production, this paper expounds the fertilizer and its use in fruit trees. 1. Types of fertilizers (1) types of fertilizers allowed to be used 1. Farm fertilizers: farm fertilizers refer to all kinds of organic fertilizers used locally and locally. It is made from a large number of biological substances, animal and plant residues, excreta and biological waste. It is rich in organic matter and humus and various major elements and trace elements needed by fruit trees, as well as hormones, vitamins and antibiotics. It mainly includes compost, retting manure, barnyard manure, biogas fertilizer, green manure, crop straw fertilizer, mud fertilizer and cake fertilizer and so on. 2. Commercial fertilizers: commercial fertilizers refer to those that are sold in the form of commodities in accordance with the provisions of national laws and regulations and under the management of the state fertilizer department. Including commercial organic fertilizer, humic acid fertilizer, microbial fertilizer, organic compound fertilizer, inorganic (mineral) fertilizer and foliar fertilizer and so on. It is mainly processed into organic fertilizers from animal and plant residues, excreta, other biological wastes, and diseases, or inorganic fertilizers in the form of mineral physics or chemical industry. 3. Other fertilizers: refer to foods that do not contain toxic substances, organic by-products of the textile industry, as well as bone meal, bone glue waste, amino acid residue, poultry and livestock processing waste, sugar factory waste and other organic matter, fertilizer that has been registered and allowed to be used by the agricultural department. (2) prohibited fertilizers 1, cities without harmless treatment or containing metals, rubber and harmful substances; 2, nitrate nitrogen fertilizers and unrotten human feces and urine; 3, fertilizer products that have not been registered. Second, fertilization methods (1) early application of base fertilizer at present, the organic matter of most orchards is less than 1%, and some orchards are even less than 0.5%, which is far from meeting the requirements of high-quality and high-yield orchards, so it is necessary to increase the amount of base fertilizer. If the dual needs of tree growth and soil improvement are considered at the same time, the application rate of organic fertilizer should be controlled at the standard of 2-3 jin per jin of fruit. Therefore, for a middle-class orchard with a yield of about 1500 kg per mu, the amount of organic fertilizer should not be less than 3000 kg. The most suitable time for applying base fertilizer is before and after fruit harvest, before fruit harvest for weak trees and after fruit harvest for strong trees. Secondly, it is applied at the beginning of the flower spike in spring. Dry and unwatered orchards in mountainous areas can not be irrigated immediately after applying base fertilizer, so base fertilizer can also be applied during the rainy season. But organic fertilizer must be fully mature fertilizer, fertilizing speed should be fast, and pay attention to do not hurt the thick root. When the source of organic fertilizer is insufficient, on the one hand, straw weeds can be mixed with organic fertilizer, on the other hand, the limited organic fertilizer should follow the principle of ensuring local and centralized distribution layer of root system, and centralized hole application should be adopted. in order to give full play to the fertilizer effect of organic fertilizer. Concentrated hole application is to dig a hole 50 cm deep and 30-40 cm in diameter from the edge of the crown, the number of which depends on the amount of fertilizer, and then mix the organic fertilizer with the soil at 1:3 or add some straw, fill the hole and water again. In addition, phosphorus and potassium fertilizer and even zinc fertilizer and iron fertilizer can be mixed with organic fertilizer to improve its utilization rate. (2) reasonable topdressing 1. Proper topdressing of nitrogen fertilizer: nitrogen is the basis for the growth and fruit of fruit trees. the application of nitrogen fertilizer within a certain limit can obviously improve the photosynthetic performance of leaves and increase tree potential and yield. But beyond the limit, it is easy to cause the branches and leaves to flourish, it is difficult to form flowers, and the fruit quality decreases. And after a large amount of nitrogen application (often irrigation after fertilizer), due to the limited absorption capacity of the root system, the excess nutrients will be leached, resulting in a great waste of fertilizer, or even too much fertilizer at one time. Therefore, while emphasizing the increase of investment in orchards, we should also take into account the needs of trees and the benefits of fertilization, and should not invest a lot of money blindly. The suitable amount of nitrogen fertilizer should be determined according to the comprehensive consideration of soil fertility, fertilizer conservation capacity and tree type. generally, 1-2 years of trees can recover 50-100 grams of urea each time, 150-200 grams of 3-4-year-old trees, and trees after 5-6 years. Generally, the amount of urea per mu should not exceed 15 kg per mu, and the amount of urea per mu is about 30-45 kg per year. 2. Topdressing nitrogen according to the ground: under the condition of insufficient organic matter, proper topdressing of available nitrogen fertilizer in barren land can obviously improve the photosynthetic performance of leaves, thus increase the accumulation level of photosynthate in trees, and play the role of "increasing carbon with nitrogen". The accumulation of photosynthate in turn promoted the growth of root system and improved the absorption capacity of root system. The thinness of trees and the difficulty of flower bud formation in barren land are all related to the level of carbon and nitrogen metabolism of plants. Therefore, properly increasing the amount of nitrogen fertilizer, increasing carbon with nitrogen and opening the road with nitrogen fertilizer are effective measures for strong trees to form flowers and yield in barren orchards. The methods of nitrogen topdressing are also different in different soils. Fertilizer began to take effect in 10-15 days after topdressing nitrogen in spring, 5-7 days in summer, and between them in autumn, which is mainly different from the level of soil organic matter and adsorption capacity. Generally speaking, the effect of fertilizer is not significant after topdressing for 20 days (high temperature season). In the barren land of mountain sand with low content of organic matter and poor fertility, the loss of nutrients with water is serious, the validity of fertilizer is shorter, and it often causes soil denitrification in the rainy season from July to August. Therefore, topdressing fertilizer in mountain sandy land should be applied frequently and less, and it is appropriate for nutrients in water to seep into the concentrated distribution layer of root system. After the rainy season, a small amount of nitrogen fertilizer can be applied to make up for the leaching loss. In the soil with high salinity and alkalinity, when the PH value is above 7.5, the content of available phosphorus in the soil is generally low, and fruit trees often have the phenomenon that twigs are not easy to form flowers because of phosphorus deficiency. This kind of soil topdressing phosphate fertilizer (soil or extra-root topdressing) is indispensable for early fruit and high yield, and topdressing phosphate fertilizer in the soil is easy to be fixed, so it is best to be mixed with high-quality organic fertilizer rich in nutrients. 3. Topdressing for trees: after the roots of fruit trees absorb nutrients, the distribution of nutrients is limited by the nutrition center, that is, nutrients are preferentially transported to the most active part of metabolism, and further promote the growth and development of this part. For example, when the new shoots are prosperous and grow, most of the fertilizer enters the parts of the new shoots, and further promotes the growth, but after the tip leaves stop growing, the central advantage of the growing part weakens or disappears, the difference of nutrients entering each organ decreases, and the distribution is more balanced. The auxiliary effect on the weak parts of the crown (such as short branches) is relatively greater, which is beneficial to the differentiation of buds. Therefore, the growth of trees is different, the amount of flowers and fruits is different, the purpose of fertilization is also different, so the period of fertilization should not be the same, fertilization must be combined with plant types. For trees with weak growth, including "small and old trees", in order to strengthen the growth of branches and leaves, we should focus on supplying nutrients when the new shoots are growing, preferably before sprouting, the early and long-term topdressing of the new shoots, topdressing combined with irrigation to promote the growth of new shoots and make the weak branches stronger. In order to alleviate the excessive growth of branches and leaves and promote short branches to differentiate buds, trees with prosperous growth but few flowers or no fruit should avoid the prosperous period and fertilize after the new shoots stop growing. The types of fertilization should also be adjusted according to tree conditions. The practice shows that nitrogen fertilizer has obvious effect on the growth of branches and leaves, and more nitrogen fertilizer is used in the rejuvenation of weak branches. Phosphorus and potassium fertilizer can alleviate overgrowth, so it is appropriate to increase the amount of phosphorus and potassium fertilizer and reduce the amount of nitrogen fertilizer for sterile trees. Topdressing is best sprinkled on the tree plate, immediately gently paddle the hoe, mix the fertilizer well, and then water it. When the tree plate is covered with grass, it can be sprinkled directly on the grass and then washed down with water, or a corner of the covered grass can be removed and sprinkled on the soil surface, then watered down, and then covered with grass. (3) extra-root fertilizer topdressing of fruit trees is to spray fertilizer directly on the aboveground branches and leaves of the tree body, which can make up for the deficiency of root absorption or as an emergency measure. Spraying fertilizer outside the root is not disturbed by the number of new roots and soil physical and chemical properties, but directly into the branches and leaves, which is beneficial to change the nutritional status of the tree more quickly. And after extra-root topdressing, the distribution of nutrients is not limited by the growth center, and the distribution is balanced, which is beneficial to the relaxation of tree potential and the promotion of weak parts. In addition, extra-root topdressing is often used for the correction of element deficiency such as zinc, iron and boron and the application of compound fertilizer. However, extra-root fertilizer spraying can not replace rhizosphere topdressing, and they have their own characteristics and should complement each other. The response of leaves to fertilizer elements was the most obvious 10-15 days after extra-root fertilizer spraying, then decreased gradually, and disappeared at 25-30 days, so if you want to play a role in a critical period, you should spray continuously every 15 days during this period. After autumn harvest, the flower and fruit development periods in spring and summer are two important periods for topdressing and spraying fertilizer outside the root. It will promote the development of floral organs, high fruit setting rate and stout short branches. In addition, the correction of element deficiency such as zinc and boron should also pay attention to the two key periods of autumn and early spring, and the effect of fertilizer spraying in these two periods is generally better than that in the growing season.