Continuous cropping obstacles for vegetables and countermeasures Continuous vegetable obstacles refer to the continuous cultivation of the same vegetables on the same plot. Even if conventional fertilizer and water management are performed, the phenomenon of poor plant growth, yield decline, and quality deterioration will occur. 1, pests and diseases increase. After continuous operation of the facility, the growth of some beneficial microorganisms (ammonium bacteria, nitrifying bacteria, etc.) is inhibited due to the physicochemical properties of the soil and changes in light, temperature, humidity, and gas, and some harmful microorganisms rapidly reproduce, and the natural balance of soil microorganisms suffers. Destruction not only results in obstacles to the decomposition process of the fertilizer, but also the occurrence and spread of pests and diseases, and increases year by year, especially common forms of leaf mold, gray mold, downy mildew, root rot, blight and whitefly. There are basically no overwintering phenomena such as maggots and spotted maggots, so that producers can only rely on increasing drug dosage and frequent drug use, resulting in serious pollution to the environment and agricultural products. 2. Secondary salinization and acidification of soil. The large amount of facilities used for cultivation and cultivation, as well as the constant year-old coverage, have changed the water balance in the natural state, and the soil has not been fully showered with rain. In addition to the high temperature and large evaporation of soil moisture, the fertilizer and other salts in the underlying soil will rise along the soil capillaries as the deep soil moisture evaporates, eventually forming a thin layer of white salt on the soil surface, that is secondary soil salt. Staining phenomenon. At the same time, due to the excessive application of chemical fertilizers, the application of organic fertilizers is too little, and the buffer capacity and ion balance capacity of the soil are destroyed, resulting in a decrease in the pH value of the soil, ie soil acidification. The increase of the concentration of soil solution increases the osmotic potential of the soil, and the germination of the crop seeds and the water absorption and absorption of roots are not performed normally. 3, the accumulation of plants from toxic substances. This is a type of growth inhibition that occurs within the species. Under continuous cropping conditions, the ecological environment of the soil has a great influence on plant growth. In particular, the metabolic products of plant residues and pathogens have a toxic effect on plants and together with the secretion of plant roots. The self-toxic substances together affect the metabolism of the plant and eventually lead to autotoxicity. 4, element balance damage. Due to the selectivity of vegetable nutrient absorption, some elements are overabundant, and some elements are excessively accumulated. Therefore, a single gargle tends to damage the balance of mineral elements in the soil. The antagonism between nutrient elements often affects the absorption of certain elements by vegetables and is prone to symptoms of deficiency of nutrients, eventually impeding fertility and reducing yield and quality. Countermeasures: First, apply straw bioreactor technology. Straws are transformed into carbon dioxide required for plant growth under the action of microbial strain scavenger, heat-resistant disease spores, enzymes, organic and inorganic nutrients, soil porosity in 20 cm plowing layer is more than doubled in the reactor planting layer. The increase of beneficial microbial populations, moderate water, fertilizer, gas, and heat have a permanent effect on continuous cropping of soil in greenhouses. The second is to increase organic fertilizer. The organic fertilizer has a comprehensive nutrient content and regulates pH, salinity, ploughability, and buffering properties of the soil. Greenhouse vegetable plots each season with high-quality farmhouse fertilizer 30 cubic meters per mu is appropriate. The use of straw to cover the field, return fertilizer to the field technology, can play a role in soil improvement, moisturizing, conservation of earthworms. Apply 150-200 kg per mu of commercial bio-organic compound fertilizer containing more than 30% organic matter. Because of its reasonable ratio of nutrition and nutrition, it also contains more organic components, which can meet the nutrient demand for vegetable growth. Then topdressing nitrogen and potassium can be fertilized. The third is balanced fertilization. The unreasonable application of chemical fertilizers, especially the excessive use of nitrogen fertilizers, is the dominant factor in the continuous development of soil barriers in vegetable greenhouses. Therefore, balanced fertilization is a key measure for greenhouse vegetable production, high yield, high quality, and high efficiency. Reasonable application of N, P and K. The general principle is to control nitrogen, stabilize phosphorus and increase potassium. In general, root and tuber vegetables are dominated by phosphorus and potassium fertilizers, with nitrogenous fertilizer; leafy vegetables are dominated by nitrogen fertilizers, suitable for phosphorus and potash fertilizers; fruits and vegetables are dominated by nitrogen and potassium fertilizers, with phosphate fertilizers. Application of nitrogen fertilizer, potassium fertilizer 50% as base fertilizer, phosphate fertilizer 100% as base fertilizer. The basal fertilizer should be fully mixed with the soil and the top dressing should be combined with irrigation for flushing or burying. Appropriate use of high-efficiency instant fertilizer and bio-fertilizer can prevent the occurrence of deficiency syndrome. According to the law of nutrient demand at different stages of crop growth, combined irrigation and supplementation should be applied to the corresponding fertigation. The fourth is a rational rotation. The use of different vegetable crops for differences in nutrient requirements and resistance to diseases and pests, and reasonable rotations, intercropping, and intercropping can also reduce the occurrence of soil and soil-borne diseases. The fifth is deep-disinfection. Deep plowing can increase soil tillage layer, break soil compaction, improve soil permeability, improve soil physical and chemical properties, and eliminate continuous cropping obstacles. Combining deep-displacement soil preparation with cotton granules for chemical disinfection can also effectively reduce the occurrence of continuous cropping obstacles. Sixth, adjust soil pH. Soil acidification caused by continuous cropping of vegetables is a common phenomenon. The pH value of the soil in the shed should be checked every year. When PH≤5.50, 50-100 kg of lime can be used per acre when turning the soil. Mix well with the soil. Can increase the PH value, but also have a killing effect on the soil bacteria.
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