A Complete Analysis of the Key Points of Pollution-Free Pomegranate Fertilization Technology
1. Five major advantages of developing pomegranate production. (1) Strong adaptability and a wide cultivation range; it can be cultivated in mountainous areas, hills, or flat sandy land. (2) Propagation and cultivation are simple and labor-saving; seedlings can be raised by cuttings or layering and root very easily; the fruit rind is hard and thick, there are fewer pests and diseases, and bagging for protection is unnecessary. (3) Bearing...
I. Fertilization PeriodsThe key to whether the fertilization periods are scientific and reasonable lies in seizing the several critical periods of nutrient demand during the growth and development of the pomegranate tree. Pomegranate fertilization is divided into base fertilizer and topdressing. Base fertilizer generally uses high-quality organic fertilizer, which can supply the pomegranate tree with various nutrient elements in a balanced way throughout the year. Base fertilizer is best applied in autumn, incorporated with deep plowing of the soil. At this time, the pomegranate root system is in its second growth peak, with many new roots emerging and fast growth; cut roots heal and regenerate easily, and the white absorbing roots that form can absorb part of the nutrients, which helps restore tree vigor and increase reserve nutrients. Moreover, most of the organic matter is fully decomposed in the soil and can be absorbed and used during the spring flowering and budbreak period of the pomegranate.
The determination of topdressing periods is mainly based on the progress of phenological phases and the needs of growth and fruiting for timely nutrient supplementation. (1) Topdressing before budbreak and after flowering: mainly to supplement the deficiency of stored nutrients, improve the fruit-setting rate and new shoot growth, with compound fertilizer as the main type. (2) Topdressing during the swelling period: to promote new shoot growth and flower bud differentiation; apply an appropriate amount of nitrogen fertilizer and more phosphorus and potassium fertilizer, with ternary compound fertilizer as the main type. (3) Topdressing before harvest: mainly quick-acting potassium fertilizer, which can promote fruit swelling and improve fruit quality; generally applied 15 days before harvest. (4) Topdressing after harvest: mainly for varieties that consume more nutrients or trees with weakened vigor, to strengthen tree vigor and increase stored nutrients.
II. Reasonably Determining the Fertilization Amount
1. Organic fertilizer serves as the basic fertilizer for pollution-free pomegranates. Judging from the fertilization level of pomegranate production in our region, the organic fertilizer application rate per mu for pollution-free pomegranate production should be 4000-5000 kg, while in production the rate per mu is only 600-800 kg. Organic fertilizer application is seriously insufficient, which increases the application amount of chemical fertilizers. This is also one of the reasons for the decline in pomegranate quality. Organic fertilizer can improve the soil, increase soil capacity, reduce environmental pollution, and significantly improve pomegranate yield and quality.
2. Soil testing and formulated fertilization. Soil testing fertilization plays a great role in improving the fruit-setting rate and maintaining sustained and stable yield increases. The determination of the fertilization amount based on soil testing must not only consider factors such as the nutrient demand for growth in the pomegranate orchard, fertilizer utilization rate, and pomegranate growth conditions, but also require comprehensive analysis and appropriate increase or decrease according to circumstances. According to measurements, for a pomegranate orchard with a yield of 2300 kg per mu, the more suitable amounts and combination ratio of nitrogen, phosphorus, and potassium are: pure nitrogen 21.2 kg/mu, pure phosphorus 18.4 kg/mu, pure potassium 9.6 kg/mu, with N:P2O5:K2O at 14:18:18. However, the suitable formula ratio is related to pomegranate yield and the soil contents of N, P, and K nutrients. Therefore, the suitable application amount of various fertilizers should be determined according to the yield and level of different pomegranates and the fertilizer supply capacity of the soil.
III. Fertilization Methods
Fertilize scientifically according to the nutrient demand characteristics of pomegranates and the properties of various chemical fertilizers. For young trees, use circular trench application, positioned at the outer edge of the tree canopy; for trees in full bearing period, use radial trench application. According to the root distribution, the radial trenches should be dug shallow on the inside and deep on the outside. The end near the central trunk is about 10-20 cm, and the end away from the central trunk is about 30-40 cm. For clay soil that is hard and compact and soil with strong fertilizer retention, deeper application may be appropriate to guide the root system to expand downward, while sandy soil loses nutrients easily and should be fertilized shallowly. The positions of the radial trenches should be changed every year to achieve the goal of soil improvement throughout the orchard.
IV. Scientifically Combined Application of Micronutrient Fertilizers
With the continuous increase of pomegranate yield and the repeated use of old pomegranate orchards, large amounts of nutrient elements are taken away from the soil every year, resulting in the deficiency of some trace elements. At present, pomegranate orchards in various places have been affected in quality and yield due to deficiencies of trace elements such as zinc and boron. When pomegranates lack zinc, spring budbreak is later, fine leaves are clustered, leaves are small, flower buds are reduced, fruit is difficult to set, fruit is small; in the early disease stage, the root system of young trees develops poorly, while old diseased trees show root rot, the canopy is sparse and cannot expand, and yield is very low. Preventive measures: (1) Soil application method: apply 0.1 kg of zinc sulfate per tree in combination with fertilization; this method has a long effective period. (2) Foliar spraying: spray zinc sulfate solution 1-2 times 2-3 weeks before flowering. The preparation ratio of the zinc sulfate solution is 36%, namely zinc sulfate 1 kg, quicklime 0.7 kg, and water 200 kg. This method can not only reduce the production of small fruit but also improve the fruit-setting rate. When pomegranate orchards lack boron, irregular necrosis appears at the top shoots in the initial stage, and the upper leaves turn yellow; with moderate deficiency, the terminal buds die and growth stops; in the final stage, the top shoots wither. Preventive measures: around the beginning of the flowering period, spray 1220.2% borax or 0.1% boric acid as foliar fertilizer 2-3 times; borax 20 g per tree can also be applied in combination with fertilization. When micronutrient fertilizers are applied to the roots, they should generally be combined with spring or autumn fertilizer application, and care should be taken not to apply too much, so as to avoid fertilizer damage.