First, the purpose of topdressing is different. In spring and autumn, vegetables are in a vigorous growth stage. The purpose of topdressing is to further promote plant growth. Most of the vegetables in the winter are in the middle and late growth stages. Due to the large amount of fruit, the nutrient consumption of the plants is too much, the growth is weak, and even premature aging occurs. In this case, the purpose of top dressing is mainly to enhance the growth of the plants, promote the expansion of the fruit, and avoid the root system. Aging, leaf senescence, premature senescence of plants.
Second, the amount of topdressing differs with the arrival of winter. The outside temperature gradually decreases, and the ground temperature in the shed also decreases. For vegetables, the growth of stems and leaves of vegetables is reduced, photosynthesis and transpiration are decreased, and root activity is decreased. Reduced, the ability to absorb water and fertilizer decreased. This is obviously different from the spring and autumn season when the temperature and ground temperature are more suitable for vegetable growth. Therefore, when topdressing in winter, it is necessary to change the practice of watering and fertilizing a lot.
The third is the application of fertilizers. Spring and autumn, high temperatures, high ground temperature, the impact of general compound fertilizer on vegetable roots is not obvious. In winter, due to the low temperature and ground temperature, the melting of the compound fertilizer into the water will further reduce the water temperature. After the application, it will not only cause the ground temperature to fall, but also cause damage to the vegetable roots, and the nutrient utilization rate of the compound fertilizer is low. The nutrient effect of the root system is poor, and even the accumulation of salt damage in the tillage layer causes the vegetables to have roots, yellow leaves and yellow heads. Therefore, in winter, topdressing should change the practice of applying general compound fertilizer in spring and autumn, and use all-water-soluble fertilizer and functional fertilizer as the main fertilizer for topdressing.
(Xue Yuhua)
Farmers Daily
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