Fruit trees should pay attention to the application of organic fertilizer.

1. Organic fertilizers should be combined with chemical fertilizers. At present, more than 90% of organic fertilizers applied in orchards are farm manure. These fertilizers contain a large amount of nitrogen, phosphorus and potassium and a certain amount of medium elements (calcium, magnesium), trace elements (iron, boron, manganese, zinc, copper, etc.) and bioactive substances, which can not only provide comprehensive nutrition for fruit trees and promote their growth, but also have a long fertilizer efficiency, and can increase and renew soil organic matter. Promote the reproduction of microorganisms and enhance the soil water conservation, fertilizer conservation and fertilizer supply capacity. However, the application amount of organic fertilizer is limited due to the shortage of organic fertilizer. According to relevant reports, only 83.1% of the orchards in the main apple producing areas in Shaanxi apply organic fertilizer, and 42% of the orchards do not apply enough fertilizer, with an average amount of only 1630 kg per mu, which is far from the actual standard of 3000 kg. As a result, the nutrient elements in the soil can not meet the needs of producing high-grade fruits and maintaining strong trees. More importantly, fruit trees need a balanced supply of nutrients, although the nutrients in organic fertilizer are very rich, but the proportion and content of nitrogen, phosphorus and potassium can not fully meet the growth needs of fruit trees. Especially in the composting process of organic fertilizer, the content of nitrogen will further decrease. If only organic fertilizer is applied to meet the nitrogen demand, phosphorus and potassium will be excessive, resulting in waste; if phosphorus and potassium just meet the needs of fruit trees, nitrogen fertilizer will be insufficient. Therefore, the application of organic fertilizer alone can not meet the needs of fruit trees for nitrogen, phosphorus and potassium at the same time, and must be combined with chemical fertilizer. Second, the application of unripe organic fertilizer is harmful to fruit trees. 1. Farm manure for burned roots mostly comes from animal manure and is rich in a lot of organic matter. When these organic fertilizers are not mature, their nutrient status is slow and can not be directly absorbed and utilized by the roots of fruit trees. if they are applied, in the process of underground ripening, it is easy to generate heat to cause root burns (commonly known as "root burning"), leading to root rot. 2. Nutrition release and tree fertilizer are not synchronized. After applying non-rotten organic fertilizer in autumn, due to low soil temperature in autumn and winter and mixing with orchard soil layer, it takes a long time for these organic fertilizers to mature underground. According to the investigation of the soil excavation in the orchard where raw manure was applied 3 years ago but no organic fertilizer was applied in the next few years, it was found that some of the raw manure were still in the original state. In the spring of the second year, although the ground temperature went up, there was generally less Rain Water in the main apple producing areas in northern China in spring, and the ripening rate of organic fertilizer applied was still very slow. at this time, the tree needs a lot of nutrients to supply the tree to blossom and bear fruit. on the other hand, the limited organic nutrition released by slow-ripening organic fertilizer can not meet the needs of trees at all. At the same time, in the process of ripening, microorganisms will consume some of the original nutrient elements (such as nitrogen fertilizer) in the root soil of fruit trees, and the trees often show malnutrition. When entering the summer and autumn of the second year, with the increase of rainfall, the ground temperature increased rapidly, and the ripening rate of Mimba was obviously accelerated last year, releasing more organic nutrients that could be absorbed by the tree, resulting in faster growth of the tree, a large number of strips, poor fruit coloring, excess vegetative growth, poor flower bud differentiation, wasting a large amount of organic nutrients and maladjustment of tree nutrition supply. 3. It is extremely easy to provoke underground overwintering pests. Unrotten organic fertilizer contains a lot of animal organic matter, so it has become an ideal overwintering place for many fruit tree pests. It is especially easy to attract all kinds of beetles (grubs), peach heart borer, inchworm, boat caterpillar, pear net bug and so on, which are extremely disadvantageous to pest control in the coming year. Third, when composting and applying organic manure in composting, the composting site should be selected in a place of leeward, sunny, and high dry terrain, agricultural film or cement floor should be laid on the composting ground, the livestock manure in farm manure should be broken, the straw should be crushed below 5 cm, and about 3% of superphosphate and dung should be mixed and piled up. The main purpose of adding calcium superphosphate is to prevent the loss of nitrogen in organic fertilizer and increase the activity of microorganisms. After the pile is made, flatten the surface with a shovel, wipe it with mud about 10 centimeters thick or cover it with agricultural film, and press it tightly around to create an anoxic environment and make it mature as soon as possible. The farm manure pile can be mature in about 60 days. When the color of organic fertilizer changes from the original gray to purple and black, the texture is loose and there is a bad smell, it shows that it is mature and should be applied to the orchard in time. When the fully mature shed bar is applied into the orchard, the parts other than the vertical projection of the crown should be selected, and the fertilizer ditch with 30-40 cm wide and 30-40 cm deep should be excavated, and the organic fertilizer should be evenly mixed with appropriate amount of chemical fertilizer (nitrogen, phosphate fertilizer) and topsoil, and then put into the bottom of the fertilization ditch, and finally covered with the bottom raw soil, or spread throughout the orchard, and then turned into the soil layer.