Magnesium is a component of chlorophyll, an activator of many enzymes, involved in fat metabolism and nitrogen metabolism, and is 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 carbohydrate.
First, the symptoms of magnesium deficiency in vegetables, when vegetables are deficient in magnesium, the late growth period, the outstanding performance is the chlorophyll content decreased, and chlorosis, often from the lower old leaves began to lose green, and gradually developed to new leaves. The mesophyll of the dicotyledonous vegetables turns yellow and chlorotic, the veins are still green, and gradually change from pale green to yellow or white, with brown or purple-red spots or streaks of different sizes, and the leaves of the whole plant are severely deficient in magnesium. Necrosis occurs. The ratio of root to shoot is reduced, flowering is inhibited, and the color of the flower is pale.
1. Soy is deficient in magnesium. In the early stage of magnesium deficiency, the veins of the lower part become pale green, then turn into dark yellow, and brown spots occur, but the leaves are still green near the base and veins, and the leaf edges are curled downwards at the later stage. Mature, the output is not high.
2. Tomato is deficient in magnesium. The leaf veins of the old leaves are chlorotic and develop to the leaf margin. When the magnesium is moderately deficient, the stems and leaves grow normally. When the magnesium is severely deficient, it expands to the small veins. Only the main stem is still green, and finally the whole plant turns yellow.
Second, the excessive magnesium application of vegetables in the field conditions, generally do not appear too much magnesium caused by poor growth of vegetable plants. However, too much magnesium may cause root development to be hindered, and the xylem of the stem is not developed.
3. Magnesium fertilizers suitable for vegetables and application techniques The magnesium-containing fertilizers commonly used are mainly water-soluble magnesium fertilizers such as magnesium sulfate, magnesium chloride, magnesium nitrate, magnesium oxide, potassium magnesium fertilizer, soluble in water, and easily absorbed by crops. Calcium magnesium phosphate fertilizer, magnesium ammonium phosphate, dolomite and other fertilizers also contain magnesium, slightly water-soluble or poorly soluble in water, slow fertilizer effect, suitable for acidic soil.
1. Magnesium sulfate. It is a neutral salt that cannot be used to neutralize acidity and is suitable for soils with a pH greater than 6. It is often used to prepare mixed fertilizers or to be sprayed with liquid fertilizer.
2. Dolomite. It is a double salt composed of magnesium carbonate and calcium carbonate, containing 21.7% of magnesium oxide and 30.4% of calcium oxide. It is mostly used to neutralize soil acidity and improve soil. Often used to formulate compost.
3. Magnesium ammonium phosphate. For long-acting compound fertilizer, in addition to magnesium, it also contains 8% nitrogen, 40% phosphorus, slightly soluble in water, and all nutrients are effective.
Application technique: It should be applied together with other fertilizers, which can be used as base fertilizer, top dressing and foliar fertilizer.
The dolomite slightly soluble in water should be applied as a base fertilizer on acidic soil. According to the calculation of magnesium, generally 1.5-1.5 kg per 667 m2 is applied. Magnesium oxide or magnesium sulfate is preferably applied on alkaline soil. For top dressing, it should be applied early, using 1%-3% magnesium sulfate or 1% magnesium nitrate, spraying about 50kg per 667m2 of spraying fertilizer, and spraying several times continuously, the effect of magnesium nitrate spraying is better than magnesium sulfate.
Fourth, pay attention to the fertilizer effect of magnesium fertilizer depends on the soil, crop types and application methods. Magnesium fertilizer is mainly applied to magnesium-deficient soils and vegetable crops that require more magnesium. For example, in sandy soil, marsh soil, acid soil, and highly leaching soil, the fertilizer efficiency is better; the fertilizer applied on the legume crop is good. Under the conditions of large application of potassium fertilizer, calcium fertilizer and ammonium nitrogen fertilizer, it is easy to cause magnesium deficiency in crops, so magnesium fertilizer should be applied together. Water-soluble magnesium fertilizer should be used as top dressing, and slightly water-soluble magnesium fertilizer should be used as base fertilizer.
First, the symptoms of magnesium deficiency in vegetables, when vegetables are deficient in magnesium, the late growth period, the outstanding performance is the chlorophyll content decreased, and chlorosis, often from the lower old leaves began to lose green, and gradually developed to new leaves. The mesophyll of the dicotyledonous vegetables turns yellow and chlorotic, the veins are still green, and gradually change from pale green to yellow or white, with brown or purple-red spots or streaks of different sizes, and the leaves of the whole plant are severely deficient in magnesium. Necrosis occurs. The ratio of root to shoot is reduced, flowering is inhibited, and the color of the flower is pale.
1. Soy is deficient in magnesium. In the early stage of magnesium deficiency, the veins of the lower part become pale green, then turn into dark yellow, and brown spots occur, but the leaves are still green near the base and veins, and the leaf edges are curled downwards at the later stage. Mature, the output is not high.
2. Tomato is deficient in magnesium. The leaf veins of the old leaves are chlorotic and develop to the leaf margin. When the magnesium is moderately deficient, the stems and leaves grow normally. When the magnesium is severely deficient, it expands to the small veins. Only the main stem is still green, and finally the whole plant turns yellow.
Second, the excessive magnesium application of vegetables in the field conditions, generally do not appear too much magnesium caused by poor growth of vegetable plants. However, too much magnesium may cause root development to be hindered, and the xylem of the stem is not developed.
3. Magnesium fertilizers suitable for vegetables and application techniques The magnesium-containing fertilizers commonly used are mainly water-soluble magnesium fertilizers such as magnesium sulfate, magnesium chloride, magnesium nitrate, magnesium oxide, potassium magnesium fertilizer, soluble in water, and easily absorbed by crops. Calcium magnesium phosphate fertilizer, magnesium ammonium phosphate, dolomite and other fertilizers also contain magnesium, slightly water-soluble or poorly soluble in water, slow fertilizer effect, suitable for acidic soil.
1. Magnesium sulfate. It is a neutral salt that cannot be used to neutralize acidity and is suitable for soils with a pH greater than 6. It is often used to prepare mixed fertilizers or to be sprayed with liquid fertilizer.
2. Dolomite. It is a double salt composed of magnesium carbonate and calcium carbonate, containing 21.7% of magnesium oxide and 30.4% of calcium oxide. It is mostly used to neutralize soil acidity and improve soil. Often used to formulate compost.
3. Magnesium ammonium phosphate. For long-acting compound fertilizer, in addition to magnesium, it also contains 8% nitrogen, 40% phosphorus, slightly soluble in water, and all nutrients are effective.
Application technique: It should be applied together with other fertilizers, which can be used as base fertilizer, top dressing and foliar fertilizer.
The dolomite slightly soluble in water should be applied as a base fertilizer on acidic soil. According to the calculation of magnesium, generally 1.5-1.5 kg per 667 m2 is applied. Magnesium oxide or magnesium sulfate is preferably applied on alkaline soil. For top dressing, it should be applied early, using 1%-3% magnesium sulfate or 1% magnesium nitrate, spraying about 50kg per 667m2 of spraying fertilizer, and spraying several times continuously, the effect of magnesium nitrate spraying is better than magnesium sulfate.
Fourth, pay attention to the fertilizer effect of magnesium fertilizer depends on the soil, crop types and application methods. Magnesium fertilizer is mainly applied to magnesium-deficient soils and vegetable crops that require more magnesium. For example, in sandy soil, marsh soil, acid soil, and highly leaching soil, the fertilizer efficiency is better; the fertilizer applied on the legume crop is good. Under the conditions of large application of potassium fertilizer, calcium fertilizer and ammonium nitrogen fertilizer, it is easy to cause magnesium deficiency in crops, so magnesium fertilizer should be applied together. Water-soluble magnesium fertilizer should be used as top dressing, and slightly water-soluble magnesium fertilizer should be used as base fertilizer.
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