Scientific Fertilization Methods and Technical Points for Plum Cultivation

I. Fertilizer Types

1. Base fertilizer: Base fertilizer is a fertilizer that can supply plum trees with various nutrients over a relatively long period. It is generally dominated by slow-release farmyard manure, such as compost, barnyard manure, crop straw, green manure, fallen leaves, etc. An appropriate amount of quick-acting nitrogen fertilizer can be added to the base fertilizer to meet the large amount of nitrogen needed by plum trees during early spring germination and flowering. Applying base fertilizer in autumn is best. In autumn, the soil temperature is relatively high, and the farmyard manure applied can fully decompose in that same year. At the same time, in autumn the root system has another growth peak, wounded roots heal easily, and new roots can grow to continue absorbing nutrients. Applying base fertilizer in spring has very little effect on the early spring germination and growth of plum trees.

2. Topdressing: According to the fertilizer requirements of plum trees at each phenological stage, a certain amount of quick-acting fertilizer is applied in stages during the growing season.

The topdressing time for plum trees is generally divided into the following periods:

(1) Topdressing before flowering: To meet the large amount of nutrition needed by plum trees during germination and flowering, quick-acting nitrogen fertilizer can be applied about 10 days before plum tree germination.

(2) Topdressing after flowering: At this time, young fruit and new shoots are both entering their growth peak. To avoid competing for fertilizer with each other, quick-acting nitrogen, phosphorus, and potassium fertilizers should be applied in time to reduce physiological fruit drop, increase the fruit-setting rate, and promote the simultaneous growth of young fruit and new shoots.

(3) Topdressing during fruit enlargement and flower bud differentiation: After physiological fruit drop and before the fruit enters the rapid enlargement stage, applying quick-acting nitrogen, phosphorus, and potassium fertilizers can greatly improve photosynthetic efficiency and promote the accumulation of nutrients in the tree. This is beneficial both for fruit enlargement and for flower bud differentiation.

(4) Topdressing in the late fruit growth stage: Apply fertilizer from when the fruit begins to color until the harvest period. This time, phosphorus and potassium fertilizers should be the main focus. Quick-acting nitrogen fertilizer is best applied as foliar spraying together with pesticide spraying, so as to avoid promoting late-autumn growth and affecting nutrient accumulation in the tree. This fertilization is extremely important for tree growth, high and stable yield, fruit quality, and the yield of the following year.

II. Fertilization amount. Generally, young vigorous trees with few fruits and soil with high fertility should be fertilized less, while large weak trees, trees with many fruits, and mountainous and wasteland areas with poor fertility should be fertilized more. For adult plum trees, apply about 50 kg of farmyard manure per plant as base fertilizer. For each topdressing, apply 250 g each of urea and potassium fertilizer per plant, and 1.5-2.5 kg of superphosphate. The concentration for urea foliar spraying is 0.3‰-0.5‰.