In recent years, due to improper use of chemical fertilizers by some peasants, the utilization rate of chemical fertilizers has been low, the cost has increased, and even crops have been damaged by fertilizer. The use of calcium, magnesium phosphate fertilizer as top dressing is slower than that of calcium, magnesium and phosphate fertilizers, and the time for fertilizer application is short. It is used as topdressing, especially in the later stage of crop growth, which not only has low utilization rate but also has poor effect. Therefore, calcium magnesium phosphate fertilizer should be used as base fertilizer and organic fertilizer mixed application, or for dressing fertilizer application. In this way, fertilizers are gradually released for crop use and have long-lasting fertilizer effects, which helps the crop grow steadily without premature decline. The use of urea and ammonium bicarbonate as surface fertilizer to produce urea, although nitrogen content is high, it must be converted into ammonium ammonia after application to the soil before it can be used for crop absorption and utilization.
At the same time, urea is in a molecular state at the time of transformation, and it will be lost with water and soil, making it difficult to use crops. Ammonium carbonate surface application, easy to volatilize, and volatile ammonia will smoke the crop stems, leaves, causing damage. Urea and other nitrogen fertilizers are used as topdressing, and trenches should be used to cover the soil. For spraying foliar fertilizers, the application concentration should be well controlled and sprayed on wheat, rice, cotton, and corn, preferably at a concentration of 0.8%-1%, and sprayed on vegetables at a concentration of 0.3%-0.5%. Direct seed dressing with superphosphate Since the superphosphate contains 3.5-5% free acid, direct seed dressing will reduce the seed germination rate and emergence rate. Therefore, the use of superphosphate as a topdressing should be deepened; for seedlings, seed should be applied 5 cm to 6 cm below or to the side of the seed, separating the seed with mud.
Potassium sulfate and potassium nitride were weakly physiologically acidic when chemical potassium fertilizer was applied alone. After applied to the soil, potassium ions were absorbed and replaced by cations in the soil colloid, and the crops were difficult to use. Therefore, the application of potash fertilizers should be combined with nitrogenous fertilizers and phosphate fertilizers. In particular, phosphorus-deficient lands such as mountains, ridges, and newly reclaimed lands should be mixed with phosphate fertilizers in order to fully utilize the potash and phosphate fertilizers. The combination of zinc fertilizer and phosphorus fertilizer has serious "antagonism" effect between zinc sulfate and superphosphate. After the two are mixed and applied, the fertilizer effect of zinc sulfate will be inhibited and its effectiveness will be reduced. Therefore, phosphorus fertilizer should be used as base fertilizer, zinc fertilizer as seedling fertilizer, or zinc fertilizer as base fertilizer, and phosphate fertilizer as seedling fertilizer, which can improve fertilizer efficiency.
Ammonium chloride and potassium chloride are applied to sugar-cane, tobacco, watermelon, citrus and other chlorine-tolerant crops to degrade the sugar content of sugarcane and watermelon due to the action of chloride ions; tobacco reduces the burning performance; and citrus light causes chronic poisoning. Long-term lusterless, affecting photosynthesis, in severe cases lead to acute poisoning, leaving the old leaves unpeeled, the new leaves stiff, slow growth, and even dead. Therefore, ammonium chloride, potassium chloride and the like containing chloride ions are applied to chloride-resistant substances such as rice, wheat, corn, and cotton to exert their desired effects.