Application Technology Of Magnesium Fertilizer For Non-pollution Vegetables
Magnesium is a component of chlorophyll, an activator of many enzymes, involved in fat metabolism and nitrogen metabolism, and is very important for regulating the activity of enzymes in plants. Magnesium content itself is an important quality standard. Increasing the application of magnesium fertilizer can increase the yield. Appropriate application of magnesium can increase the content of chlorophyll, carotene and carbohydrates.
1. Symptoms of Magnesium Deficiency in Vegetables
When vegetables are deficient in magnesium, symptoms appear in the later stages of growth, and the outstanding performance is the decrease of chlorophyll content and the occurrence of chlorosis, which often starts from the lower old leaves and gradually develops to new leaves. The mesophyll between the leaf veins of dicotyledonous vegetables turns yellow and chlorotic, the leaf veins are still green, and gradually changes from light green to yellow or white, and brown or purple-red spots or stripes of different sizes appear. Necrosis occurs. The root-to-shoot ratio is reduced, flowering is inhibited, and the color of the flowers is pale.
1. Soybean is deficient in magnesium. In the early stage of magnesium deficiency, the veins of the lower leaves turned light green, then dark yellow, and brown spots occurred, but the base of the leaf and near the veins remained green, and the leaf margins curled downwards in the later stage, turning yellow from the edge inward, early. Mature and low yield.
2. Tomatoes are deficient in magnesium. Vein tissue of old leaves loses its green color and develops towards leaf margins. Stems and leaves grow normally in moderate magnesium deficiency, and expand to small veins in severe magnesium deficiency. Only the main stem remains green, and finally the whole plant turns yellow.
Second, the symptoms of excessive magnesium application in vegetables
Under field conditions, symptoms of poor growth of vegetable plants due to excessive magnesium generally do not occur. But sometimes too much magnesium can cause the root development to be blocked and the xylem in the stem to be underdeveloped.
3. Magnesium fertilizer types and application techniques for vegetables
Commonly used magnesium-containing fertilizers mainly include water-soluble magnesium fertilizers such as magnesium sulfate, magnesium chloride, magnesium nitrate, magnesium oxide, potassium-magnesium fertilizer, etc., which are soluble in water and are easily absorbed and utilized by crops. Calcium magnesium phosphate fertilizer, magnesium ammonium phosphate, dolomite and other fertilizers also contain magnesium, which is slightly water-soluble or insoluble in water, and has a slow fertilizer effect, which is suitable for acidic soil.
1. Magnesium sulfate. It is a neutral salt, it cannot be used to neutralize acidity and is suitable for soils with a pH value greater than 6. It is mostly used to prepare mixed fertilizers, or mixed with liquid fertilizers for foliar spraying.
2. Dolomite. It is a double salt composed of magnesium carbonate and calcium carbonate, containing 21.7% magnesium oxide and 30.4% calcium oxide. It is mostly used to neutralize soil acidity and improve soil. It is often used to prepare mixed fertilizers.
3. Magnesium ammonium phosphate. It is a long-acting compound fertilizer. In addition to magnesium, it also contains 8% nitrogen and 40% phosphorus. It is slightly soluble in water, and all the nutrients it contains are effective.
Application technology: It should be applied together with other fertilizers, and can be used as base fertilizer, top dressing and foliar fertilizer.
Dolomite, which is slightly soluble in water, should be applied as basal fertilizer on acidic soil. Calculated by magnesium, generally 1-1.5kg per 667m2. Magnesium oxide or magnesium sulfate should be applied on alkaline soils. As top dressing, it should be applied early, with 1%-3% magnesium sulfate or 1% magnesium nitrate, spraying about 50kg of fertilizer solution per 667m2, and spraying several times in a row. The effect of magnesium nitrate spraying is better than that of magnesium sulfate.
Fourth, matters needing attention
Magnesium fertilizer efficiency depends on soil, crop species and application method. Magnesium fertilizers are mainly applied to magnesium-deficient soils and vegetable crops that require more magnesium. For example, the fertilizer effect is better on sandy soil, swamp soil, acid soil, and highly leaching soil; the fertilizer effect on legume crops is good. Under the conditions of applying a large amount of potassium fertilizer, calcium fertilizer and ammonium nitrogen fertilizer, it is easy to cause magnesium deficiency in crops, so magnesium fertilizer should be applied in combination. Water-soluble magnesium fertilizer should be used as top dressing, and slightly water-soluble magnesium fertilizer should be used as base fertilizer.
