1. Soil application
Calcium fertilizer is applied directly to the soil, allowing the plant to absorb calcium through the roots. This method is suitable for use in the early stage of plant growth or when the soil is severely deficient in calcium, and can be used as basal fertilizer or top dressing.
Soil application of calcium fertilizer generally choose alkaline or neutral calcium fertilizer, such as limestone, gypsum, calcium nitrate, etc., the amount and time of application should be determined according to soil type, crop type, growth stage and other factors. In general, acidic soils require more alkaline calcium fertilizer, and alkaline soils require less neutral or acidic calcium fertilizer.
Crops require more calcium fertilizer during the vigorous growth and fruiting periods, and less calcium fertilizer during the dormant and germination stages. Calcium fertilizer applied to the soil should be mixed evenly with other fertilizers, and avoid being applied at the same time with chlorine-containing fertilizers or trace element fertilizers to avoid antagonism.
2. Foliar application
Calcium fertilizer is dissolved in water and sprayed on the foliage of the plant to allow the plant to absorb calcium through the leaves. This method is suitable for use in the late stage of plant growth or fruit development, and can be used as top dressing or for the prevention and treatment of calcium deficiency.
Foliar calcium fertilizer generally chooses fast-acting or water-soluble calcium fertilizer, such as calcium nitrate, calcium magnesium sulfate, boron calcium Caboron, AminoCa etc., and the application concentration and frequency should be determined according to the needs of crops and climatic conditions. Generally speaking, the concentration of foliar application should not be too high, so as not to cause leaf burns, and it is generally controlled between 0.2% ~ 0.5%.
The frequency of foliar application should be appropriate to avoid waste or excessive accumulation, and it is generally sprayed every 10~15 days. Foliar applications should be carried out in the morning or late afternoon and avoid when the sun is strong or the temperature is too high.
3. The period of use of calcium fertilizer
Generally speaking, calcium fertilizer needs to be applied at the beginning of planting and during the vigorous growth period, which is the period when the plant grows most rapidly and can better absorb and utilize calcium. Moreover, during the fruiting and flowering periods, it is also necessary to apply calcium fertilizer appropriately to improve the quality and yield of crops.
4. Reasonable combination of other fertilizers
Calcium fertilizer cannot be used with ammonium nitrogen fertilizer, potassium fertilizer, etc., otherwise it will reduce the effect of calcium fertilizer. At the same time, calcium fertilizer should not be used with fertilizers with high phosphorus content, because phosphorus and calcium can form insoluble calcium phosphate precipitates in the soil, reducing fertilizer efficiency. Therefore, when using calcium fertilizer, it is necessary to reasonably mix other fertilizers.
5. Apply in moderation
The amount of calcium fertilizer needs to be determined according to the type of crop, growth, soil condition and other factors. Generally speaking, when using base fertilizer, 10-20 kg of lime or gypsum per acre needs to be applied, or 50~100 kg or superphosphate should be applied.
In the application process, it is best to mix with organic fertilizer, evenly sprinkle calcium fertilizer on the soil surface, and then plough into the soil, which can not only improve soil acidity and alkalinity, but also improve sufficient calcium fertilizer for crop growth.
7. Manifestations of calcium deficiency in plants
(1) Wheat: the growth point and stem tip die, the plant is dwarf or clustered, the young leaves often cannot be expanded, and the leaves that grow often lack green. The root system is short, with many branches, and the root tip secrets a transparent fluid that is attached to the root tip like a sphere.
(2) Corn: the plant is short, the leaf edge is sometimes white serrated and irregularly broken, the tip of the stem is hooked, the tip of the new leaf is adhered and cannot be stretched normally, and the tip of the old leaf is also brown and scorched.
(3) Potato: pale green stripes appear on the edge of the young leaves, and the leaves are shrunken. In severe cases, the terminal buds die, and the lateral buds grow outwards in clusters. The roots are susceptible to necrosis, the tubers are small, there are deformed strings of small tubers, and the vascular cells on the surface and inside the tubers are often necrosis.
(4) Rice: The symptoms first occur in the roots and the tender parts of the ground, and the plants are short and decay before they are old. Young leaves are curled and withered. The front end of the new leaves and the leaves are green and yellow, and the old leaves are still green, with less fruit and more grains.
(5) Soybean: the leaves are curled, small gray-white spots will appear on the old leaves, the leaf veins will turn brown, the petioles will be weak and drooping, and they will soon wither and die. The tip of the stem is hook-like and curly, and the new young leaves cannot be stretched and are easy to die.
(6) Peanuts: scars appear on the back of old leaves, and then brown dead patches occur on the front of the leaves, with many empty pods and seeds that are not full.
(7) Cotton: the plant is short, the leaves are aging, there are few fruit branches, there are few boll sets, the growth point is seriously inhibited, it is hook-shaped, and the leaves fall off in advance. In severe calcium deficiency, the new petioles droop and fester.
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(8) Tobacco: The leaf color is light green, and the apical bud is bent downward, and the tips and edges of the young leaves are withered. The plant is dwarfed, unusually dark green, and when extreme lacking, the terminal bud dies. The lower leaves are thickened, and sometimes there are some dead reddish-brown spots. If there is a lack of calcium during the flowering period, the flowers and buds have a tendency to wither. The top of the corolla is so dead that the pistil protrudes prominently, and dead spots may appear on the corolla.
(9) Tomato: the upper leaves turn yellow, the lower leaves remain green, the growth is stunted, and the top buds often die. The young leaves are small and tend to turn brown and die. Near the apical stems often have blight. The roots are thick and short, and there are many branches, and the flowers fall off less, and the top flowers are particularly easy to fall off. Umbilical rot occurs in the fruit, and in the early stage of fruit expansion, the flesh of the umbilicus appears water-soaked necrosis, and then the diseased tissue collapses, blackens, shrinks and sinks.
(10) Cucumber: The leaf edge is like inlaid with gold edge, transparent white spots appear between the leaf veins, most of the leaf veins lose green, and the main veins can still remain green. The plant is dwarfed, the internodes are short, the top nodes become dwarfed obviously, the new leaves are small, and the later stage is dry from the edge inward. When calcium deficiency is severe, the petiole becomes brittle and easy to fall off, and the plant begins to die from the top, and the dead tissue is grayish-brown. The flowers are smaller than normal, the fruits are smaller, and the flavor is poor.
(11) Apple: The young leaves on the new branches appear faded or necrotic spots, and the leaf tips and leaf margins are curled downward. Older leaves may partially die. Bitter pox disease often occurs on the fruit, sunken spots appear on the surface of the fruit, and the flesh tissue becomes soft and has a bitter taste. Apple heart disease is also caused by calcium deficiency, the flesh is translucent and water-stained, expanding radially from the center to the outside, and finally the pulp is filled with juice in the intercellular space, resulting in internal decay.
(12) Peach: The young leaves of the top branches are dried up from the tip of the leaf and the leaf edge or along the midrib, and the tip of the twig is dry and a large number of leaves are lost in severe cases.
(13) Grape: between the veins and leaf margins of young leaves, then needle-like necrotic spots appear near the leaf margins, and the stems and vines wither at the top of the top.