Apple orchard fertilization should be carried out early according to the growth规律 of the trees, ideally between September and October. The high temperatures and humidity at this time facilitate root healing and the decomposition of organic fertilizer. The entire garden should be fertilized one meter away from the trunk, with a depth of about 50 centimeters. The main type of base fertilizer is farmyard manure, with the amount of chemical fertilizer calculated at 1.5-2 kilograms per kilogram of fruit produced. Typically, 4,000-5,000 kilograms of organic fertilizer per acre, along with 40 kilograms of diammonium phosphate and 200 kilograms of草木灰, is recommended. The method of fertilization varies by garden, and for densely planted orchards, alternate-row fertilization can be used, fertilizing the rows not fertilized the previous year, which saves labor and effort.
The apple tree's root system is mainly distributed within the soil layer from 0 to 40 centimeters, with two peak growth periods throughout the year, and the autumn growth peak. The apple tree's nutrient absorption characteristics are: initially dominated by nitrogen, followed by potassium in the middle and later stages, and a relatively stable phosphorus absorption throughout the year. Therefore, the following points should be considered when applying fertilizer:
According to the yield load, the amount of fertilizer should be balanced. Apples absorb nitrogen, phosphorus, and potassium in a ratio of 1:0.5:1. Generally, to produce 100 kilograms of fruit, 0.8 kilograms of nitrogen, 0.4 kilograms of phosphorus, and 0.8 kilograms of potassium are required. According to information from China Agri-Resources Network, autumn is the late growth stage of fruit trees, and potassium fertilizer should be the main focus to promote fruit expansion and sugar accumulation, thereby enhancing quality.
Seize the Timing of Fertilization. Generally, apply base fertilizer after the harvest of fruits and when the root growth peak arrives, following the cessation of shoot growth in autumn. In Beijing, this typically occurs from September to October. This approach ensures that the fruit trees absorb the nutrients while preventing excessive shoot growth in autumn.
Combining the use of organic fertilizer, chemical fertilizer, and foliar feeding. Organic fertilizer is generally used as base fertilizer, with cow and sheep manure, and chicken manure both suitable options. Fertilization can be applied using specialized orchard spreaders, which are mostly of the spreader truck style. In terms of total fertilizer application, the amount of cow and sheep manure should follow the "one pound of fruit, one pound of fertilizer" guideline, while chicken manure can be halved. In autumn, fertilization should be based on this total amount, supplementing the deficiencies in spring fertilization with additional fertilizer quantity and types. Primarily, this depends on the tree's vigor and the year's yield and load, with attention to supplementing certain amounts of nitrogen fertilizer, potassium dihydrogen phosphate, and other foliar fertilizers.
Pay attention to the location and depth of fertilization. Generally, circular or semi-circular furrows are suitable for young trees. Strip, hole, radial furrow, and broadcast fertilization methods are more commonly used for mature trees. The depth of fertilization is usually around 40 centimeters, and as the tree canopy expands, the fertilization area and depth should also be increased accordingly, ideally targeting the main root distribution layer.
Typically, fertilization can be combined with deep plowing and soil improvement in orchards. Apple trees differ from field crops, as the soil nutrients around their roots, due to years of absorption by the root system, are already quite depleted and the soil is heavily compacted. Deep plowing and fertilization can improve the growth environment for the root system.
