Second, the partial application of nitrogen fertilizer, the ratio of nitrogen, phosphorus and potassium is imbalanced, thereby inhibiting the absorption and utilization of trace elements and forming yellow leaves.
Third, excessive application of fertilizer containing humic acid, change soil physical and chemical properties, acidification, is not conducive to root development and growth, nutrient absorption and transformation is not smooth, the leaves appear yellow due to malnutrition.
Fourth, only pay attention to the application of chemical fertilizers, neglecting organic fertilizers, soil porosity is reduced, permeability is poor, roots are not breathing well, resulting in yellow leaves caused by malnutrition.
The fifth is blind watering, the humidity in the field is too large, affecting root respiration and nutrient absorption, leading to yellow leaves.
Sixth, pests and diseases, especially after the hazard, the root absorption capacity is reduced, the leaf nutrient supply is insufficient, and in severe cases, dryness and death occur.
After the yellow leaves appear in the leek, it is necessary to distinguish between different situations and prevent them in advance. Generally, the following measures can be taken:
1. Add organic fertilizer, use NPK fertilizer reasonably, supplement trace elements, and ensure a balanced supply of nutrients. According to the characteristics of leek and fertilizer, the application of phosphorus and potassium fertilizer and trace elements should be paid during the raising period. It can be used in the middle to late September to mid-October, or before the shed, and the application of Chuxing potassium sulfate compound fertilizer is 50-75 kg per mu. Application of medium and trace element fertilizer 10 ~ 15 kg; spraying in the growing season 2 ~ 3 times chlorophyll, spray Shibao and other foliar fertilizer.
2, timely and reasonable watering. In the case of ensuring that the soil in the field is moist, the amount and frequency of watering are reduced. Generally, the interval between sandy soils is shorter, and the interval between clay soils is longer. After watering, the cultivating soil is loose and wet, increasing soil permeability.
3, prevention of pests and diseases, the use of high-efficiency and low-toxic pesticides to reduce the hazards of cockroaches. It can be watered once in the middle and late August to the middle of September and 3 to 5 days after the shed, generally 1000-1500 grams of Agricultural Dart or 1000-1500 grams of Xinnongbao per acre, or 5~ When 10 cm high, phoxim is poured, and 1500-2000 g per mu can be used.
Fertilization management of amaranth yellow leaves
First, the lack of trace elements. The amaranth with yellow leaves is generally not applied or sprayed with trace elements such as iron, copper and zinc, and yellow leaves are formed due to the lack of such elements.
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