Pay attention to the problem when using foliar fertilizer
Foliar fertilizers have been widely used in agricultural production due to their characteristics such as quick effect, high utilization rate, low dosage, simple application method and obvious yield increase effect. So, how can we maximize the use of its benefits without adverse consequences? The author believes that the following points should be noted when using. First, the selection of leaf fertilizer targeted crop plants mainly absorb nutrients from the soil, the content of elements in the soil plays a decisive role in the growth of the plant. Therefore, before determining the selection of leaf fertilizer species, the contents of soil elements and soil acidity and alkalinity should be determined firstly, and the presence of elements in the plant body can also be determined conditionally, or the type of leaf fertilizer can be determined according to the external characteristics of the deficiency syndrome. And dosage. It is generally believed that in the case of under-application of basal fertilizer, foliar fertilizers containing nitrogen, phosphorus and potassium may be used. When sufficient basal fertilizer is used, foliar fertilizers mainly composed of trace elements may be selected. For example, the falling of bells of cotton is related to the deficiency of boron nutrition, so it is generally applied in the budding period 2-3 times, combined with topdressing of boron fertilizer, can obtain the effect of Baolei Baoling; the “cracking stem disease†of celery It is also caused by the lack of boron, can be sprayed with borax or boric acid to supplement. Second, the solubility of leaf fertilizer is better because the foliar fertilizer is sprayed directly into the solution, so the foliar fertilizer must be dissolved in water. Otherwise, the insoluble matter in the foliar fertilizer can not be absorbed after being sprayed on the surface of the crop, and sometimes it may even cause damage to the leaves. Therefore, the fertilizer used for spraying should have higher purity, less impurities, and generally no more than 5% water-insoluble matter in the fertilizer. Third, the acidity of leaf fertilizer should be suitable for different nutrient elements under different acid and alkaline conditions. To maximize the benefits of fertilizer, there must be a suitable range of acidity, generally requiring a pH of between 5-8. If the pH is too high or too low, in addition to the absorption of nutrient elements, it will also cause harm to the plants. Fourth, the concentration of leaf fertilizer should be appropriate because the foliar fertilizer is sprayed directly on the surface of the crop above the ground, different from the root fertilization, soil buffering effect is gone. Therefore, we must master the spraying concentration of leaf fertilizer. When the concentration is too low, the amount of nutrients that the crops are exposed to is small, and the use effect is not obvious. When the concentration is too high, the leaves are often burned to cause damage. However, the same fertilizer is sprayed at different concentrations on different crops and should be based on the type of crop. Such as urea: the general crop spraying concentration of 1%-2%; open field vegetables, fruits and other crops spraying concentration is generally 0.5%-1%, greenhouse spraying concentration of 1%-2% on vegetables; open ground vegetables, fruits The spray concentration on other crops should be controlled at 0.2%-0.4%, and the seedling spraying concentration on the nursery seedlings should not be higher than 0.2%. Trace elements can be applied as well as foliar sprays. However, because some trace elements are easily precipitated in the soil and lose their effectiveness, it is best to use foliar sprays for production. The spray concentration is usually 0.3%-0.5% aqueous solution. The application concentration of copper and molybdenum should be appropriately reduced. Fertilizer spraying period of vegetables in the middle of five, leaf fertilizer with the physicochemical properties of the fertilizer with the use of the decision of some nutrients easily deteriorated, so some foliar fertilizer to be used with the distribution, can not exist for a long time. Such as ferrous sulfate leaf fertilizer, the new preparation should be light green, no precipitation, if the solution becomes auburn or auburn precipitation, indicating that the low-priced iron has been oxidized into high-priced iron, fertilizer efficiency has been greatly reduced. If the ferrous sulfate solution is formulated with a slightly alkaline or high calcium content, precipitation and oxidation will be accelerated. Therefore, in order to reduce the formation of precipitates and slow down the oxidation rate, when preparing the ferrous sulfate solution, first add 10 ml of mineral acid per 100 liters of water, or add 100-200 ml (about 100-200 g) of vinegar to acidify the water. And then dissolve the ferrous sulfate with acidified water. Of course, some organic chelated iron fertilizers such as iron ferrous falfeate and iron polyflavonoids may also be used instead of ferrous sulfate. Sixth, leaf fertilizer spraying time should be appropriate in order to extend the wet time of the fertilizer solution is foliar, is conducive to the absorption of elements, leaf fertilizer spraying time is best selected in the evening before and after the wind is not much. This can delay the drying speed of the leaf droplets and facilitate the penetration of ions into the blades. Spray it evenly so that the front of the blade is wet. After spraying foliar fertilizer in case of heavy rain, it should be sprayed again. Seven, as an effective measure to adjust the deficiency of plants, it is widely used. However, in order to exert the maximum benefit of the leaf fertilizer, the most critical fertilizer application period should be selected according to the growth of different crops in order to achieve the best results.