What are the varieties of calcium fertilizer? Which soils and crops are prone to calcium deficiency?

At present, calcium fertilizers commonly used in production are quicklime, which contains 94% ~ 96% calcium (CaO); hydrated lime, which absorbs water from quicklime and contains calcium 64% calcium 7526; carbonate lime, made from fine grinding of limestone and marl, is mainly composed of calcium carbonate; gypsum is mainly composed of calcium sulfate. In addition, some nitrogen, phosphorus and potassium fertilizers also contain a certain amount of calcium.

The application of calcium fertilizer can be divided into base fertilizer and topdressing fertilizer:

①-based fertilizer is mainly used to improve soil. Acidified soils cultivated in acidic soils or protected areas generally need to apply lime, 50 kilograms per 667 square meters, and gypsum 100 kilograms per 667 square meters on alkaline soils.

② topdressing. For plants that have appeared symptoms of calcium deficiency, 0.3% 0.5% calcium nitrate or calcium chloride can be sprayed continuously for 2 or 3 times, each time at an interval of 7 days, with a better corrective effect.

Which soils and crops are prone to calcium deficiency?

Calcium-deficient soils in China are mainly distributed in acid red soils and sandy soils with low exchange capacity in the south of China. The pH of saline soil in the coastal areas of North China, Northwest and Northeast China and Southeast China is more than 9, and the soil is mainly composed of sodium and low exchangeable calcium, some of which are only 1 mg / 100g soil, which can easily lead to calcium deficiency in crops. It should be pointed out that sometimes the soil is not deficient in calcium, but high salinity in the soil will affect the absorption of calcium by crops and lead to symptoms of calcium deficiency in crops, which should be distinguished.

The demand for calcium varies from crop to crop. The crops that need more calcium are purple grass, asparagus, bean, pea, soybean, sunflower, sweet clover, peanut, tomato, celery, Chinese cabbage, potato, sugar beet, grape and so on, while cereal crops such as rice and wheat, pineapple and peach trees need less calcium. Therefore, in the same kind of soil, crops that need more calcium are prone to calcium deficiency.