Once the crisis of repeated cropping occurs, it will disturb the normal physical and chemical properties of the soil after a long time, which will eventually lead to a reduction in vegetable production, and even unsuitable for vegetable cultivation.
Among the vegetables planted, bitter gourd and other melon vegetables are the most affected by repeated cropping, followed by tomatoes and peppers, but it is the vegetable that can bring the most benefits to vegetable farmers, the more susceptible to the impact of repeated cropping.
Causes of continuous cropping obstacles
First, single continuous cropping leads to an uneven distribution of soil nutrients.
A certain vegetable crop has a preference for the absorption of certain nutrients. Long-term continuous cultivation of the same vegetable will inevitably lead to a lack of certain nutrients, and the balanced distribution of nutrients in the soil will inevitably be out of balance. In addition, the root distribution of different vegetables is different, and long-term single continuous cropping will cause a lack of nutrients in certain soil layers.
Second, a single continuous crop makes the soil harmful bacteria increase and stubborn.
Due to long-term continuous cultivation, vegetable root exudates and decomposed root residues in the soil provide rich nutrients and hosts for harmful bacteria. With the increase of continuous cropping years, the types and quantity of harmful fungi increase, the content of actinomycetes decreases, and the plots that cause about 70% of vegetable continuous cropping obstacles are caused by soil infectious diseases and insect pests.
Third, the self-toxic substances secreted by the root system.
Some crops can release some toxic substances through the decomposition of plant residues and root secretion, which can inhibit the growth of plants of the same species or the same family or the same family in the next crop. This phenomenon is called autotoxicity. Autotoxicity is one of the factors that cause continuous cropping obstacles in crops. A large number of experiments have shown that phenols and certain fatty acids can inhibit plant growth.
Fourth, changes in soil salinization and physical and chemical properties caused by continuous cropping and fertilization.
Long-term large-scale use of the same type of fertilizer will make the soil nutrients unbalanced, and eventually make the soil acidify and salt damage.
No workaround
Prevention and resolution of the hazards of double cropping should be focused on the two aspects of soil treatment and fertilizer use.
1. Soil treatment
Reduce harmful bacteria, diseases and insects in the soil through high-temperature stuffy sheds and chemical treatment, so as to achieve the effect of suppressing the damage of repeated cropping. Vegetable farmers can apply soil fumigant, such as lime nitrogen, to treat the soil when the temperature is the highest from July to September every year.
2. Reasonable fertilization
First, increasing the amount of high-quality organic fertilizers and keeping the structure of aggregates in the soil will not decrease will allow the soil to have continuous fertilizer supply capacity. Second, pay attention to the use of biological bacterial fertilizer. Third, the proportion of base fertilizer application should be adjusted according to the different fertility of the crops and soil.
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