Among the essential elements for the growth of vegetables, calcium is a medium-quantity element, and the content of calcium in the soil is very rich. In the natural cultivation state of vegetables, calcium should generally not be deficient. The reality is that calcium deficiency often occurs. For example, calcium deficiency causes umbilical rot in tomatoes and peppers, dry Chinese cabbage and lettuce, and brown spot in potatoes. The reasons are mainly the following situations.
I. Deterioration of soil conditions causes calcium deficiency
Due to repeated planting and other reasons, soil degradation has been caused by soil compaction, soil acidification, and soil salinization. When the soil is compacted, the aeration of the soil becomes worse, the factors such as water and nutrients are not coordinated, the effectiveness of calcium is reduced, the root system of the plant is stunted, and the fruit and vegetable vegetables with strong growth and need more calcium often show calcium deficiency; In acidified soils, the concentration of hydrogen ions increases, and hydrogen ions antagonize the absorption of other cations by vegetables, impede the absorption of calcium ions, and cause calcium deficiency in acidified soils. Soil salinization is similar to soil acidification. Increased sodium ions affect the absorption of calcium in the root system. Deterioration of the soil condition leads to a reduction in soil fertility, that is, a decrease in soil organic matter and microorganisms, hindering the conversion of effective nutrients in the soil, and further causing a series of deficiency symptoms including calcium deficiency.
Second, irrational fertilizer caused by calcium deficiency
Blindly pursuing yield and excessive application of chemical fertilizers, especially large amounts of ammonium nitrogen fertilizers, can cause calcium deficiency, which frequently occurs in vegetables such as cabbage and tomatoes. The main reason is that the physiological acidic ammonium nitrogen is too much, resulting in too much ammonium ion in the soil solution, which produces antagonistic effects with calcium and magnesium ions and affects the absorption of calcium and magnesium by vegetables. Potassium ion and calcium ion also have antagonism. Excessive application of potassium fertilizer can also cause calcium deficiency. However, there is less occurrence of large-scale application of potassium fertilizer.
Third, the lack of calcium caused by the development of vegetable roots
In the back-season cultivation of vegetable facilities, many vegetables are in an environment that is not suitable for their own growth and development. The growth and development of vegetables often appear obstacles, especially the absorption capacity of the root system is reduced, even if there are a lot of effective nutrients in the soil, including effective calcium ions Vegetables are also difficult to absorb.
IV. Infectious diseases cause calcium deficiency
When vegetables are infected with bacteria, they are often more likely to show symptoms of calcium deficiency and other nutrients. The main reason is that the physiological functions of vegetables are hindered. For example, tomato infected with virus disease, the umbilical rot and tendon rot also increased significantly.
Fifth, adverse environmental conditions caused by calcium deficiency
Vegetables encounter adverse environmental conditions, such as high temperature, low temperature, drought, water damage and other hazards, easily lead to calcium deficiency.
After the occurrence of calcium deficiency and other deficiency factors in vegetables, many vegetable farmers only pay attention to supplement calcium fertilizer and trace fertilizer, may be a temporary solution to the symptoms of nutrient deficiency, but did not solve the underlying problem, and even emphasis on excessive use of calcium fertilizer and other fertilizers, Due to the antagonism between ions, it is easy to cause other deficiency syndromes. Farmers should look for the reasons for their formation, treat them symptomatically, implement the “prevention-based, comprehensive prevention and control†policy, focus on the prevention of soil-based prevention, and fundamentally address the occurrence of calcium deficiency. Specific measures include the following.
First, fertilize the soil. Improve the soil fertility, so that the soil has a "fat, fertilizer, satiety, hungry," the buffer capacity, which is to prevent the lack of vegetables to produce the first condition. Of course, fertilizing the soil should change the concept of re-fertilization of chemical fertilizers and light application of organic fertilizers, changing only the three elements of soil nutrients (ie, nitrogen, phosphorus, and potassium), and neglecting the concept of three elements of soil nutrients (ie, minerals, organic matter, and microorganisms). To avoid blindly pursuing production and ignoring product quality. Promote the application of organic fertilizers and biological bacterial fertilizers to improve soil fertility, coordinate soil water, fertilizer and gas heat, and create a healthy soil environment for crops.
Second, cultivate robust seedlings and grown plants. Robust plants can enhance the ability to absorb nutrients and resistance to adverse environments, not only preventing the occurrence of a deficiency syndrome, but also increasing the disease resistance of crops.
Third, create the environmental conditions needed for the normal growth and development of vegetables. The environmental conditions suitable for the growth of vegetables not only prevent the occurrence of deficiency syndromes, but also improve the stress resistance and resistance of vegetables. Therefore, vegetable growers should strengthen their cultivation and management, especially under conditions of facility cultivation, regulate external conditions such as temperature, moisture, and air, strengthen water and fertilizer management, do a good job of prevention and control of pests and diseases, and prevent the physiological function of vegetables from declining, and thus produce physiological factors such as calcium deficiency. Diseases create conditions for the high yield and quality of vegetables.
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