With the increase in the year of land cultivation, the yield per unit area of ​​crops has been continuously increasing. In particular, the amount of organic fertilizers has been decreasing year by year, the phenomenon of defertilization and lack of elements in soils has become increasingly prominent, and the farmers’ response has become more and more intense. In the production practice, farmers are unclear about the timing and symptoms of defertilization and nutrient deficiency, and often cannot apply fertilizers to the disease and seize crops for high yields. The following describes the main symptoms and countermeasures of de-fertilization and nutrient depletion in maize.
First, remove fat. Farmers think that the crops are deferred, mainly due to the lack of nitrogen, phosphorus, and potassium element fertilizers, and they are mainly manifested in the early stage. However, in the production, the small amount of fertilizer needed in the early stage of the seedlings will not appear in the early stage of crops. Taking corn as an example, defertilization began to show up around ten leaves of corn. If corn lacks nitrogen, phosphorus and potassium, it must check the leaves. In the absence of nitrogen fertilizer, generally the first leaf underneath is obvious, starting from the tip of the leaf to the petiole where it is more neat; yellow phosphorus deficiency symptoms and nitrogen deficiency The same, the difference is that the yellow leaves appear light purple; after checking the nitrogen and phosphorus, then check the symptoms of potassium deficiency, potassium deficiency leaves, generally in the absence of nitrogen, phosphorus top leaves, where leaves yellow, both sides of the veins Greenish, with a charred appearance at the tip of the blade, is an apparent potassium deficiency. After finding out the reasons for the lack of fat, corresponding measures can be taken.
Second, the lack of factors. It refers to the lack of trace element fertilizers in crops.
1. Deficiency of magnesium and zinc deficiency are first manifested in old leaves. Magnesium deficiency appears yellow stripes on the old leaves of the corn and develops toward the tip of the leaf. The edges and tips of the leaves are light purple and die wither. In the absence of zinc, white bands appear on both sides of the old leaves. In the 3-5 leaf stage of young seedlings, young leaves with zinc deficiency were yellowish-white, with green margins and withering at later stages.
2. The symptoms of copper deficiency, sulfur, iron, and boron are mainly manifested in the upper leaves. When the copper is lacking, the top heart leaves turn yellow, and the growth is hindered. The veins of the leaves are chlorotic, and the plants are clustered and withered and die. When the corn lacks sulfur, the upper part of the new leaves is yellow, the leaves are thin, and the plants are dwarfed and stiffened. In the absence of iron, the young leaves in the upper part of the plant were chlorotic and yellow. In severe cases, the veins were yellow and the whole leaves turned white. In the absence of boron, the upper leaves turn yellow, with yellow-green stripes, and the leaves are soft and sagging, accompanied by black shifts.
3. In the absence of calcium and boron, the symptoms are reflected in the tip meristem. When the corn lacks calcium in the middle and later stages, the top new leaves stick to each other, there is a black jelly, the old leaf coke is yellow, and the leaves are jagged. In the absence of boron, white spots appear on the upper leaves, and the white lines are synthesized. The growth points are inhibited, and it is difficult to develop and the growth and development are seriously impeded.
three. Countermeasures. The first is to do everything possible to increase the use of agricultural fertilizer, increase the strength of poles and trees, and improve soil grade levels. The second is to implement shallow anti-15-20 centimeters, deep loose 35-45 centimeters, and expand the area of ​​autumn land. The third is the use of various elements of fertilizers due to time, place, crops, and demand, increasing the use of micro fertilizers. The fourth is to increase the use of mixed fertilizer and fungus fertilizer.
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