1. Performance and Causes of Continuous Cropping Obstacles in Facilities Vegetables
1.1 Continuous Performance of Vegetable Vegetables
Facilities agriculture is a brand-new production mode under the concept of modern agricultural production. Vegetable cultivation is the main form of agricultural production. In the process of cultivation of facilities for vegetables, continuous cropping is a very serious hazard. Continuous cropping is the main cause of aggravation of pests and diseases. There are several major hazards in continuous cropping. First, the soil acidification is serious. Continuous cropping will lead to increased acidification of the soil. The acidic soil environment is not conducive to the growth of vegetables. Second, the scarcity of trace elements and the scarcity of trace elements are the main hazards of continuous cropping in the cultivation of vegetable facilities. In particular, trace elements such as calcium, magnesium, and sulfur are less likely to cause deformity and growth disorders in vegetables. Third, the severity of soil diseases has increased. As continuous cropping will lead to serious breeding of various pathogenic fungi and bacteria in the soil, such as tomato bacterial wilt and cucumber wilt disease, etc. will continue to increase. Fourth, secondary salinization occurs in the soil. In the continuous cropping land, the soil salinity is very high, generally exceeding 200% of the normal land mass. The salinized soil has a very negative impact on the growth of vegetables.
1.2 Analysis of Continuous Crop Obstacles to Facilities Vegetables
1.2.1 Causes of serious soil acidification.
The main reason for soil acidification is that the amount of fertilizer used in the cultivation of vegetables is inaccurate. In some areas, large amounts of chemical fertilizers are used to promote the growth of greenhouse vegetables. In particular, some physiological acidified fertilizers are used more often, resulting in a decrease in the buffer capacity of the soil and failure to recover the soil. Because of its own ion balance ability, it causes the p H value of the soil to decrease again and again, causing serious acidification. In addition, during the production of greenhouses, there is less natural rainfall, and the accumulation of acid ions in the soil leads to soil acidification. According to research, the PH value of the soil in vegetable greenhouses grown for five consecutive years decreased by 1.5-2 points compared with the general land mass. Acidification environment has a great influence on the germination of vegetable seeds and the development of root system.
1.2.2 The causes of insufficient trace elements in soil.
Trace elements are the key to the growth of vegetables. During the cultivation of facilities for vegetables, many households plant vegetables with relatively simple varieties. Continuous planting will selectively absorb nutrients in the soil, resulting in a trace element in the soil. Less content. In addition, during the cultivation process, some users use more nitrogen, phosphorus and potassium fertilizers, which are insufficient for the supplement of trace elements, resulting in the lack of trace elements in the soil.
1.2.3 Causes of serious soil pests and diseases.
The continuous cropping of vegetables will lead to a decrease in the number of pathogenic antagonistic bacteria in the soil, and the root exudates of vegetables will also provide good conditions for the growth of a variety of underground pathogens, resulting in a continuous increase in the number and types of pathogenic bacteria in the soil, coupled with the growing farmers in the management process. The indiscriminate use of chemical fertilizers and pesticides has resulted in the suppression of beneficial microorganisms in the soil and aggravated soil diseases.
1.2.4 Causes of increased secondary salinization in soil.
The secondary salinization of soil is mainly related to fertilization. Due to unscientific fertilization, the contents of various elements in the soil are unbalanced. For example, there are more nitrogenous fertilizers and phosphate fertilizers, and less potassium is used. The use of trace element fertilizers is ignored. , It has a certain influence on the development of the roots of vegetables, which causes vegetables to absorb no more nutrients from the soil, and the environment of greenhouses is generally closed. The lack of natural rainwater washing, the high temperature inside the greenhouse, the evaporation of soil moisture will cause the lower layer The salt content in the soil increased, and a serious secondary salinization phenomenon was formed on the surface of the soil.
2. Ways to control the continuous crop damage caused by vegetable facilities
2.1 Adhere to Scientific Rotation
In the agricultural production process, continuous cropping is generally not recommended. Crop rotation is the basis for the growth of crops. Scientific and rational crop rotation can reduce soil deterioration and reduce pest and disease incidence. It is also the main way to break down the continuous cropping hazards of vegetable installations. For example, in the cultivation of vegetables, it is possible to adopt the mode of paddy-upland rotation and dryland rotation. The effect of rotation between paddy and dry land is good. It can achieve the goals of washing acid and salt and optimizing the microbial community. It is good for soil acidification, salinization and various diseases. The inhibitory effect.
2.2 Adhere to Scientific Fertilization
Excessive use of chemical fertilizers is the main cause of continuous crop failure in vegetable facilities. In order to increase the growth level of vegetables, it is necessary to effectively control the amount of chemical fertilizers, formulate fertilization, and provide the nutrients needed for vegetable growth. At the same time, we should adhere to the application of organic fertilizer during the fertilization process to reduce the use of chemical fertilizers, combine organic fertilizers with chemical fertilizers, use organic fertilizers to improve soil structural performance, and use some chemical fertilizers to provide trace elements for vegetables. At the same time, the mixed use of organic fertilizers and chemical fertilizers can also effectively control the lack of nutrients caused by continuous cropping, optimize the pH of the soil, and coordinate with inorganic non-enrichment to ensure balanced nutrition and improve plant resistance.
2.3 Adhere to biological control
In the process of continuous vegetable planting, pests and diseases are relatively serious. The biological control method is a green and recyclable control method widely popularized at present. It has good control effect on the pests and diseases caused by continuous cropping, and will not cause harm to vegetables. The beneficial microorganisms can be used to treat some pathogenic bacteria in the soil, cultivate beneficial microorganisms, and invade the nutrition and space of the pathogenic bacteria, so that the living space of the pathogenic bacteria is compressed, thus realizing the effective prevention of diseases and insect pests. At present, the most common way is to introduce antagonistic bacteria and inoculate beneficial microorganisms, which can increase the number and role of soil microbial populations.
2.4 Controlling the Greenhouse Environment
2.4.1 Control lighting.
Lighting conditions are the key point in the cultivation of vegetables, and they are also a prerequisite for ensuring the healthy growth of vegetables. Especially in the early spring and early winter season, the temperature is low, the lack of light affects the photosynthesis of vegetables, and the lack of light can also lead to a comparison of the environment in the greenhouse. Dark, providing conditions for the occurrence of pests and diseases. In this regard, it is necessary to control the lighting conditions during the cultivation of vegetables in the facility. Generally, a non-drip film with good light transmission is selected, and a light curtain can also be set to maintain the cleanliness of the film surface and increase the light level.
2.4.2 Humidity and temperature control.
Humidity and temperature are important parameters in the greenhouse. During the humidity and temperature control process, it is necessary to actively create a suitable environment for the growth of vegetables, and to prevent the occurrence of high-humidity, high-temperature and other environments, and to prevent the occurrence of pests and diseases caused by continuous cropping. For example, during the cultivation of vegetables, it is necessary to control the number and total amount of watering. If severe weather occurs, such as heavy rainfall, drainage should be performed in time to prevent waterlogging disasters, and in particular, large quantities of underwater water must be avoided. Infiltration into the soil leads to rotted vegetables.
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