At present, in the orchard fertilization due to the influence of traditional habits, people only pay attention to the input of nitrogen, phosphorus, and potassium fertilizers, but the calcium supply is insufficient, and the physiological diseases caused by calcium deficiency increase year by year, resulting in apple bitter pit, pox spot disease Occurrence of such a large area has caused great economic losses to the fruit farmers. I stationed in September 2002 and conducted soil analysis and analysis of 29 apple high-yield farms in Zhaoyuan City, Shandong Province. The results showed that the average replacement soil calcium in 21 orchards was 832 mg/kg, which was higher than that of apple bitter pits. The critical value of 1000mg/kg is lower than 168mg/kg, and the remaining 8 soils have an average substitutional calcium content of 1139mg/kg, which is slightly higher than the critical value of calcium required for bitter apple disease, indicating that a large part of orchard soil replacement calcium is satisfied. Apple needs normal development. Based on several years of experimental studies, the authors have summarized a set of techniques for identifying calcium deficiency symptoms in apples and comprehensive calcium supplementation techniques, which are presented below. 1 The Role of Calcium Calcium is an essential nutrient for apples and an important component of cell walls. In the absence of calcium, cells do not divide normally. In severe cases, the growth point is necrotic and physiological diseases are easily caused. Calcium can not only inhibit fungal invasion, reduce the infection rate of diseases, but also reduce the toxic effects of certain ions in the soil. 2 Calcium Deficiency Symptoms Calcium in the fruit tree is easy to form insoluble calcium precipitate and is fixed, belonging to the nutrients that can not be transferred and reused. Therefore, the symptoms of calcium deficiency in apple are first manifested in the newborn tissue: 1 root symptoms. The formation of multi-branched short and thick root groups, the masses called "broom root", severe root death. 2 leaves symptoms. Results The tree shoots stopped growing prematurely, the young leaves curled, the edges of the leaves were yellow, and the veins in the leaves had necrotic spots. 3 fruit symptoms. When the fruit is nearly mature (in early September), it begins to appear. As the time delays, the condition further expands and spreads. Small brown necrotic spots appear on the surface of the fruit. The pulp shrinks into a sponge and the fruit heart is water-stained and forms bitter pit disease. , woody scab, and water heart disease, especially the apple bagging caused by the lack of calcium and more serious physiological diseases. 3 The calcium supplementation technology test survey found that soil acidity (pH 3.1 adjust soil pH, increase soil exchangeable calcium content soil acidity is closely related to the effectiveness of the soil calcium, generally acidic orchard soil calcium Inadequacies must adjust the pH of the orchard soil to a suitable range.The reason that the acidity of the orchard soil is stronger than the soil parent material and climatic factors is mainly caused by unreasonable fertilization, such as potassium sulfate and potassium chloride commonly used in production. Ammonium chloride and Other physiological acid fertilizers, after the application of soil cations (NH4 +, K +) absorbed by fruit trees, leaving acid roots.And then some orchards long-term use of superphosphate fertilizer itself contains large amounts of free acid, which will make the soil acidic year by year Strengthen the method to solve the soil acidity: 1 change the fertilizer, nitrogen fertilizer is mainly urea, phosphate fertilizer is changed to calcium magnesium phosphate fertilizer, potassium fertilizer uses potassium sulfate, 2 calcium supplement, generally calcium carbonate 60--70kg per 667 square meters, with Improve soil acidity, thus directly increasing the exchangeable calcium content of the soil.With 2--3 years of application, the soil pH can be adjusted to 6.5--7.5; Too much nitrogen fertilizer will affect the absorption of calcium 3.2 Increasing organic fertilizer and improving the retention of calcium on the soil Increasing organic fertilizer is effective in increasing soil organic matter content, improving soil physical and chemical properties, and enhancing the ability of soil to maintain calcium. According to the survey, after repeated application of organic fertilizer, orchards with soil organic matter content greater than 1.3% in successive years, there are few occurrences of calcium deficiency in apple, which is due to high soil organic matter content, good soil aggregate structure, and increased soil calcium. At the same time, the organic fertilizer is generally neutral and alkaline, which can reduce the activity of cationic iron and aluminum in the soil, reduce the influence of cations in the soil on the activity of substitutional calcium, and ensure the absorption of calcium by the root system; A large number of trace elements can continue to provide calcium and microelement nutrition for apples.Therefore, the orchard should increase the amount of organic fertilizer, generally reaching more than 4000kg per year per 667 square meters. 3.3 Foliar spray fertilizer, the whole study of calcium supplementation proves that young The fruit period is the most prolonged period for apple to absorb calcium.Because of the poor mobility of calcium, calcium supplementation must be implemented. The time should begin two weeks after the apple is dropped. , Foliage 350 times liquid amino acid calcium or 800 times liquid ammoniacal calcium liquid fertilizer, spraying once every 12 - 14 days, and even spray 2 - 3 times.The bagging of apples before bagging even 2 Subsequent foliar calcium fertilizer to ensure sufficient calcium nutrition in young fruit; 40 to 50 days before fruit picking, and then sprayed once; for long-term storage after fruit picking, dipping with 4% calcium chloride solution 3 Minutes, washed with clean water and then stored, can prevent diseases during storage, extend the storage period, increase economic efficiency.
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