Calcium is an indispensable element for crop growth, due to the development of agriculture and changes in farmers' concepts, the use of calcium fertilizer is becoming more and more common, the amount of use is also getting bigger and bigger, many growers ask, there are many types of calcium fertilizer products on the market, how to choose to use calcium fertilizer? How to use calcium fertilizer, the effect will be good?
First, the symptoms caused by calcium deficiency
Calcium in the body of the crop is relatively poor mobility, mainly through the transpiration of crop leaves to move upwards, once the soil calcium is insufficient, it is easy to show symptoms of deficiency. When calcium is deficient, it mainly shows the following symptoms.
1. Cause the occurrence of diseases
After the lack of calcium in crops, the most common is to split the fruit, such as grapes, pomegranates, tomatoes, etc. in the middle and late stages of growth, the peel cracks. At the same time, the resistance of crops to diseases is weakened, resulting in the occurrence of various diseases. The common bitter pox disease on apples, leaf scorch disease on vegetables, and umbilical rot disease on tomatoes are all diseases caused by calcium deficiency.
2. Crop growth is slow
Calcium is less mobile in the crop body, so it is easy to show symptoms of deficiency in the new leaf area. Once the new leaves lack calcium, the growth of the new leaves is slow, the leaves are yellow and curly, and in severe cases, the leaves are dry and fall off. Since crop growth requires auxin secreted by new slightly new leaves to regulate root absorption of nutrients, when the growth of new slightly new leaves is abnormal, it affects the absorption of nutrients by the roots, thus causing the problem of slow growth of crops.
3, crop yield, quality decline
Calcium deficiency affects the photosynthesis of crops, while inhibiting the ability of roots to absorb nutrients, resulting in weak crop growth and prone to premature aging. Moreover, calcium is an important component of fruit epidermal cells, and calcium deficiency will cause the crop stalk to be weak and the grain to be incomplete. For fruit trees, the tree is weakened, the transformation rate of various nutrients of the fruit is slower, the fruit is easy to crack and fall fruit, and the commodity rate is greatly reduced.
Second, the classification of calcium fertilizer production process
1, firing calcium fertilizer: such as quicklime, hydrated lime, etc., is made of limestone, dolomite, oysters, mussel shells, etc., the main component of calcium oxide, the content of 35-90%.
2, biological calcium fertilizer: such as shrimp and crab shells, animal bones, etc. crushed, its main component is calcium carbonate, calcium oxide content of 25-30%.
3. Chemical synthesis of calcium fertilizers: such as calcium superphosphate, calcium chloride, calcium nitrate, the calcium oxide content is about 20%, 48%, and 30%, respectively.
4, chelated calcium fertilizer: representative products such as lactose calcium citrate, EDTA chelated calcium and sugar alcohol calcium, sugar alcohol calcium is the chelation of sugar alcohol and calcium nitrate, its role is mainly sugar alcohol can quickly transport calcium ions, to achieve the purpose of rapid calcium supplementation, calcium oxide content is generally greater than 16%. Can be used for foliar spraying.
Third, the precautions for the selection of calcium fertilizer
1, according to the soil conditions of the reasonable selection of calcium fertilizer, such as acid soil can choose lime as calcium fertilizer, alkaline soil can choose gypsum as calcium fertilizer.
2, foliar spraying, to choose chelated calcium fertilizer or EDTA chelated calcium, should not use chemical synthesis of calcium fertilizer and fired calcium fertilizer, otherwise it will burn leaves, resulting in fertilizer damage.
3, the advantages and disadvantages of calcium fertilizer does not depend on the content of calcium, that is, "calcium supplementation is the key in absorption", plants only absorb ionized calcium, other compound states of calcium fertilizer need to be decomposed into ionized calcium after the plant can absorb.
Fourth, how to scientifically carry out calcium supplementation
At present, there are more calcium fertilizer products, such as common lime, gypsum, sugar alcohol calcium, lactose calcium citrate, calcium superphosphate, calcium nitrate, lime nitrogen, calcium chloride, calcium hydroxide and so on. In actual production, how do we choose to supplement crops with calcium? According to the cause and purpose of calcium deficiency, the appropriate product should be selected to supplement the crops with calcium.
1. Calcium deficiency caused by soil deterioration
Fertilizers are now used all year round, resulting in acidification of the soil. In this case, a large amount of calcium in the soil is adsorbed and fixed by the soil as a stable compound state that cannot be absorbed by crops and causes calcium deficiency, especially in the greenhouse vegetable planting process, which is more common.
In view of this situation, we should choose quicklime for calcium supplementation, and sprinkle 40-60 kg of quicklime per acre of land, which can not only supplement calcium for the soil, but also improve the acid-base balance of the soil, improve the content of effective calcium in the soil, thereby reducing the occurrence of calcium deficiency. In addition, when using fertilizers, more calcium, magnesium and phosphorus fertilizers, calcium nitrate, calcium superphosphate and other products can supplement nitrogen, phosphorus and potassium for crops at the same time, supplement a certain amount of calcium for the soil.
2. Foliar spray calcium supplementation
There is a critical period and a maximum nutrient uptake period for crops. The demand for a certain element in these two periods is relatively large and the amount is large, and the movement of calcium in the crop is poor, and it is easy to appear that the calcium absorbed by the root system cannot meet the demand during these two periods, such as the expansion period of the fruit.
In this case, we should choose the foliar spray method to supplement the crop with calcium through the leaves. Sugar alcohol calcium or chelated calcium can be selected during the young fruit stage and expansion stage of the fruit.
3. Increase the effective calcium content of the soil
Many soils have sufficient calcium content, but the soil solidifies into a stable compound state that cannot be absorbed by the roots and causes calcium deficiency. In the usual fertilization process, we should pay attention to the use of organic fertilizer and biological bacterial fertilizer, by supplementing the soil with organic fertilizer and beneficial microorganisms, increase the adglomerate structure of the soil, and the adjudicular structure can adsorb a large number of calcium ions to supply crops to absorb and prevent solidification by the soil, thereby improving the active state content of calcium elements and reducing the occurrence of calcium deficiency.
4. Reasonable watering
Calcium transport in the crop relies on the transpiration of leaves, and when the soil is dry, the transpiration effect is weak and can also cause calcium deficiency. Therefore, in agricultural production, it is necessary to strengthen field management, timely watering to improve soil moisture during drought, which is conducive to the absorption of calcium by crops and prevents calcium deficiency in crops.