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Symptoms of sulfur deficiency in vegetables. Vegetables are deficient in sulfur, plants are generally deficient in green, and late growth is inhibited. Generally, the yellowing begins on the young leaves (buds), and the veins are first greenish and spread throughout the whole leaves. When severe, the old leaves turn yellow and even white, but the mesophyll is still green. The stems are weak, the roots are slender and unbranched, the flowering is delayed, the shell rate is high, and the fruit is small. When the nitrogen supply is sufficient, the symptoms of sulfur deficiency mainly occur in the new leaves of vegetable plants. When the supply of nitrogen is insufficient, the symptoms of sulfur deficiency occur on the old leaves of vegetables.
Excessive sulfur application symptoms in vegetables. Excessive application of sulphur fertilizer in field conditions can cause abnormal growth and metabolism of vegetable plants, and the leaves are dark red or dark yellow. The leaves have water-stained areas, which develop into white necrotic spots in severe cases.
Sulfur fertilizer type and application method suitable for vegetables. The commonly used sulfuric acid fertilizers in production mainly include gypsum, sulfur, calcium, ammonium sulfate and potassium sulfate.
Gypsum is the most important sulphur fertilizer. It is directly pulverized into gypsum by gypsum ore. It is slightly soluble in water. Generally, it should pass through No. 60 mesh to be applied to vegetable fields. Agricultural gypsum has three kinds of gypsum, plaster and phosphorus.
Raw gypsum: ordinary gypsum, containing 18.6% sulfur. It is white or off-white and slightly soluble in water. It should be ground before use and passed through a 60 mesh sieve.
Plaster: Also known as alabaster, it is made by the heat of dehydration of raw gypsum. It is easy to grind, the color is pure white, and the hygroscopicity is strong. After water absorption, it becomes ordinary gypsum. It is easy to form a block and should be stored in a dry place.
Phosphorus-containing gypsum: It is the residue produced by the decomposition of sulfuric acid into phosphate rock powder to obtain phosphoric acid. The main component is gypsum, about 64%, containing 17.9% sulfur, which is acidic and easy to absorb moisture.
Gypsum is applied to the soil as a fertilizer, which not only provides sulfur fertilizer, but also provides calcium fertilizer. Gypsum should be applied when the soil available sulfur is less than 10 mg/kg. Can be used as base fertilizer, top dressing and seed fertilizer. The dry land is used as the base fertilizer, and 15-25 kg of gypsum powder per acre is applied to the surface, and the soil is mixed. For seed fertilizer, the dosage per acre is 3-4 kg.
In addition to being used as fertilizer, gypsum is mainly used to improve alkaline soil. When applied, it is deeply turned over after application of soil surface, and washed with salt to remove salt. The plaster has long aging effect, except for the effect of the year, sometimes the effect of the second year and the third year. Better, don't have to apply every year.
Sulfur is mostly powdery, hardly soluble in water, irritating to the skin, easy to catch fire, and should not be added to the mixed fertilizer. It is generally granulated with bentonite. In soils with high leaching strength, the fertilizer efficiency is better than that in dry soil, and the fertilizer effect is better than that of gramineous vegetables in cruciferous, leguminous and bulbous vegetables.
Sulfur fertilizer can be used as base fertilizer and top dressing. Generally, the dosage per mu is about 5 kg. Mix as much as possible with the soil when applying. As the base fertilizer is removed, the application period should be earlier than gypsum, and the dosage per acre is 1-2 kg. Used to improve alkaline earth, the application method is the same as that of gypsum. However, the dosage should be reduced accordingly.
In areas with high temperatures and heavy rains, organic matter is less likely to accumulate, and sulfate ions are more lost, making it a region that is prone to sulfur deficiency. Sandy soil is also prone to sulfur deficiency. When the effective sulfur content in the soil is less than 10 mg/kg, vegetable plants are highly likely to have sulfur deficiency. However, the soil water and water are poorly ventilated, and the poisoning of sulfur may also occur.
Therefore, sulfur fertilizer should be applied to sulfur-deficient soil. There are more sulphur, such as cruciferae and legumes. High-yield fields and long-term application of non-sulfur fertilizers should pay attention to the application of sulfur-containing fertilizers.
Pollution-free vegetable sulfur fertilizer application technology
Sulfur is a component of sulfur-containing amino acids, proteins, and many enzymes that form and are found in glycoside oils of onions, garlic, and cruciferous plants. In recent years, due to the long-term application of high concentrations of non-sulfurized fertilizers (such as urea, ammonium phosphate, potassium chloride, etc.), some plants that require more sulfur (such as soybeans, onions, garlic, etc.) have poor growth and development.
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