1. In the whole growth period, it is mainly based on topdressing nitrogen fertilizer. It masters the fertilization principle of “early topdressing and promoting growth, medium-controlled fertilizer prevention and long-term follow-up, and then heavy topdressing and attacking yieldâ€. Many mature vegetable fields that grow vegetables all year round will have some soil aging. The main performance is the increase of pathogens and residual toxicity, soil compaction, lack of organic matter, due to the large application of compound fertilizer, diammonium and other chemical fertilizers, neglecting the application of organic fertilizers, causing soil compaction, reduced permeability, aerobic microbial activity decline, root dysplasia, easy Affected by the disease.
2. Excessive application of chemical fertilizer, the pH value of the vegetable field is increased, and the soil salinization is aggravated. The application of trace element water-soluble fertilizer is insufficient. The trace elements such as zinc, boron, iron and molybdenum in the soil for many years are widely absorbed by vegetables, and when they are not supplemented, these trace elements will be reduced year by year, which seriously affects the growth and development of vegetables. The soil layer is shallow, and the vegetable plots are mostly used for manual excavation. The intercropping of intercropping plants is less digging, the soil layer is gradually shallower, which affects the root extension, while the lettuce field does not appear because of the long time of planting vegetables. The above phenomenon, thus the utilization rate of fertilization is high, and the effect of increasing production is remarkable.
The principle of lettuce fertilization:
In order to make the lettuce grow normally and obtain good benefits of increasing production and income, it is necessary to fertilize properly, so that the vegetable land maintains a proper nutrient concentration, so that the lettuce maintains a moderate plant "seepage" effect. The principle of scientific fertilization is:
1. Add a large amount of decomposed organic fertilizer. Especially for cooked vegetables, it is advisable to stop using chemical fertilizers and a single nitrogen fertilizer.
2. Persist in applying organic fertilizers such as plant straw, manure and human and animal manure throughout the year to improve the agglomerate structure of the soil and make the water, fertilizer, gas and heat significantly coordinated. The acidified or alkalized soil should be modified. In addition to the application of organic fertilizer, moderate fertilizer should be applied. If the soil is acidic, lime or grass ash is neutralized, the soil is alkaline, and ammonium sulfate or superphosphate can be applied. Calcium regulation to improve the acidification properties of the soil.
3. Implement reasonable rotation of different vegetables. Whether it is lettuce or cooked vegetables, it is not advisable to plant the same vegetables on the same vegetable field for several consecutive times. It should be repeated for a long time.
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