Hebei Messi Biology Co., Ltd. stated that magnesium is a forgotten nutritional element in China and many other countries. The application of magnesium fertilizer in Europe has a history of more than 80 years, and the application amount of magnesium fertilizer in Europe reaches one million tons (calculated as magnesium sulfate), which is the highest in the world. Magnesium deficiency in soil in China is also quite serious. Statistics from the agricultural sector show that there are 210 million mu of soil with moderate magnesium deficiency and 140 million mu of land with severe magnesium deficiency.
The Institute of Magnesium (IMI), which was established before September 2016, takes plant magnesium nutrition, the interaction of magnesium and other trace elements with other nutrients as the main research object, and proposes three combined orientations – the combination of industry, agriculture and business, and the foundation of plant nutrition. Combination with applied research, theory and practice. Faced with the serious shortage of magnesium in China’s land, the Institute of Magnesium is based in China and radiates to the world, which undoubtedly caters to the new needs of the Chinese market.
With the increase of intensive agricultural production, the problem of magnesium deficiency in crops has become increasingly prominent, and the demand for magnesium fertilizer application has become increasingly urgent. In the early 1960s, the application of magnesium fertilizer on the acidic red soil in southern my country could significantly increase the yield of rice and soybean. In the 1970s, rubber trees in Hainan Island showed a large area of yellow leaf symptoms due to magnesium deficiency, and crops such as peanuts, rapeseed, potatoes, sugar beets, and corn also showed good responses to the application of magnesium fertilizers. After the 1980s, with the improvement of the multiple cropping index, the increase of crop yield, the large-scale application of high-concentration compound fertilizer, and the continuous reduction of the use of farmyard manure, the phenomenon of magnesium deficiency in crops has become more and more serious, and the effect of increasing the production of magnesium fertilizer has become more and more effective.
Soil magnesium content gradually decreases from north to south and from west to east
Magnesium content in soil in my country tends to decrease gradually from north to south and from west to east. The magnesium content (MgO) in the northern soil is generally 5-20g/kg, with an average of about 10g/kg. g/kg, the average is around 5g/kg.
Soil exchangeable magnesium content (extracted with 1.0 mol/L NH4OAc at pH 7.0) can better reflect the status of soil magnesium supply and can be used as a diagnostic index of soil available magnesium. For many plants, 60mg/kg is the critical value of magnesium deficiency, and the status of soil magnesium supply is also affected by other cations. Soil exchangeable magnesium saturation (%) is also an index to measure the soil’s magnesium supply capacity. When the saturation of exchangeable magnesium is lower than 10%, there is a possibility of magnesium deficiency. Its value varies according to the magnesium requirement of the crop:
The exchangeable magnesium saturation of pastures that need more magnesium is between 12% and 15%, while the demand of most crops is 6% to 10%, the value of legume crops is not less than 6%, and the value of general crops cannot be lower than 4%. %. In addition, it is generally required that the soil Ca/Mg ratio should be between 12-17. When the exchangeable Ca/Mg ratio is greater than 20, magnesium deficiency is prone to occur. The exchangeable K/Mg ratio is required to be between 0.4 and 0.5, and it is lacking when the soil K/Mg ratio is higher than 1.0. Therefore, excessive application of potassium fertilizer and lime will induce magnesium deficiency in crops. The form of nitrogen fertilizer applied will also affect the effect of magnesium fertilizer. NH4+ has an antagonistic effect on the absorption of Mg2+, while NO3- can promote the absorption of Mg2+ by crops. The degree of adverse effect of different nitrogen fertilizer types on magnesium absorption was: ammonium sulfate>urea>ammonium nitrate>calcium nitrate. Therefore, the appropriate amount of nitrogen, phosphorus and potassium fertilizers, combined with the application of organic fertilizers or nitrate nitrogen fertilizers, is conducive to the effect of magnesium fertilizers.
According to the results of the Ministry of Agriculture’s soil test and formula fertilization test, 44% of the soil in my country has an exchangeable magnesium content lower than 50mg/kg, and the proportion of cultivated land lower than 25mg/kg is as high as 36%. The results of Xu Minggang’s magnesium application experiments on 22 kinds of crops showed that when the soil exchangeable magnesium content was lower than 50mg/kg, the application of magnesium fertilizer showed an increase in yield, and when it was lower than 25mg/kg, the average yield increased by more than 10%.
The provinces of Fujian, Jiangxi, Guangxi and Hainan in tropical and subtropical humid areas of South my country are the regions with the most severe magnesium deficiency. Various crops have different requirements for magnesium. Generally, fruit trees, leguminous crops, root and tuber crops, tobacco, sugar beet, etc. need more magnesium than cereal crops; fruit vegetables and root vegetables need more magnesium than leafy vegetables. Magnesium has a good yield-increasing effect on crops such as citrus, grapes, vegetables, potatoes, sugarcane, tobacco, oil palm, sugar beet, perennial pasture, rubber and olive, and attention should be paid to the application of magnesium fertilizer on these crops.
The acidity and alkalinity of the soil should be considered when applying magnesium fertilizer
1. Slow-acting magnesium fertilizers such as magnesium oxide, magnesium hydroxide, magnesium carbonate, dolomite powder, and calcium-magnesium phosphate fertilizer should be applied to strongly acidic soil. Soil acidity, eliminate H+, Al3+, Mn2+ poison.
2. Magnesium sulfate and kabeinite should be applied to weakly acidic and neutral soils. Magnesium fertilizer can be used as base fertilizer, topdressing and root topdressing.
3. Water-soluble magnesium fertilizer should be used as top dressing, while slightly water-soluble magnesium fertilizer should be used as base fertilizer. Use 2% to 5% MgSO4·7H2O solution foliar spraying to correct the symptoms of magnesium deficiency and get quick results. Spray once every 7-10 days, and spray 2-3 times continuously.
The magnitude of the effect of magnesium fertilizer is also related to the amount of application. For example, when too much magnesium fertilizer is applied to rubber, the magnesium content in leaves and latex will be too high, causing early coagulation of latex, increasing the barrier of degumming, which is not conducive to rubber production. According to reports, the magnesium fertilizer application rate (MgO) of food crops is 25-45kg hm-2; the magnesium fertilizer application rate (MgO) of economic crops is 40-60 kg hm-2; MgO) is 50-90kg·hm-2.