With the rise of growing vegetables in greenhouses, soil-borne diseases have intensified. At present, soil-borne diseases in greenhouses have become one of the major problems that threaten the safe production of vegetables. To solve this problem, crop rotation is one of the most effective methods. Therefore, today we will learn about the crop rotation technology in greenhouses. Change the stubble without changing the soil, one acre is worth two acres?, "Plant the land without changing the stubble, and you will be blinded nine times out of ten years", "There is no need to ask about crop rotation, it is better than applying manure at the end of the year?" These agricultural proverbs from Chinese folk have been passed down for countless generations. , How many years, there are not many sentences, but the principle is very simple, that is, farming must carry out crop rotation.
The concept of crop rotation technology
Crop rotation refers to the planting of different types of vegetables on the same farmland in the same greenhouse according to a certain number of years. For example, tomatoes, celery, cucumbers, green onions, etc. These vegetables usually belong to different families in terms of biological classification. The process of changing vegetable varieties is called cropping. If it is not replaced, it is called repeated cropping, and continuous cropping is continuous cropping.
Continuous cropping obstacles
Continuous cropping and repeated cropping will cause very serious harm to the growth of some vegetables. The growth will become weaker and weaker, the yield will drop significantly, and the quality of vegetables will become worse and worse. We usually call it continuous cropping disorder, and it is also called soil disease in many places.
1. Reasons for obstacles to continuous cropping in greenhouses
The main reasons for obstacles to continuous cropping in greenhouses include the following aspects:
(1) Insufficient soil nutrients Uniform
Continuous cropping will cause the soil nutrients to be out of balance. Different types of vegetables have different nutrient needs during the growth process, so the levels of nutrient absorption are also different.
(2) Primary salinization of soil
Continuous cropping will also cause secondary salinization of greenhouse soil, which is what we often call anti-alkali, and anti-alkaline soil due to mineral Excessive ion concentration will hinder the absorption of water by vegetable roots, and may even cause water to leak out from the exposed roots and stems, thus affecting the normal growth of vegetables.
(3) Vegetables produce autotoxicity
There is also a strange phenomenon in continuous cropping, which causes vegetables to produce autotoxicity, that is, vegetables poison themselves. This is because some vegetable root exudates and plant residues will release some toxic substances, such as phenolic acid compounds such as benzoic acid, when they rot and decompose in the soil. These substances have an inhibitory effect on the growth of the vegetable's own root system, such as new roots becoming branched and slowing growth. Moreover, these substances are not suitable for decomposition and can accumulate in the soil with the increase in the number of continuous vegetable cropping and cropping, thus affecting subsequent crops of vegetables. have serious consequences for their growth.
(4) Continuous cropping will aggravate pests and diseases
Continuous cropping will cause the continuous accumulation of vegetable pests and diseases. This is because each vegetable or the same type of vegetables grows in a specific growth environment. There will be specific germs and pests. Due to the suitable temperature and humidity and other environmental conditions in the greenhouse, these pathogens and pests often stay in the soil with diseased remains or attach themselves to the surface of the walls of the greenhouse, where they can survive longer. If the next crop of vegetables is planted with the same kind or the same Types of vegetables provide suitable hosts for these pathogens and pests, giving them a rich source of food, so that they can multiply quickly. In particular, the number of pathogens and pests living in the soil, such as Fusarium that causes melon wilt and nematodes that cause root-knot nematodes, will accumulate and increase, causing serious harm to the growth of subsequent crops of vegetables. .
In fact, it is not difficult to solve the obstacles to continuous cropping. These hazards will be eliminated by themselves after crop rotation. Therefore, the key lies in us mastering the scientific method of crop rotation. Before understanding this method, let’s first understand what types of vegetables we commonly cultivate.
How to carry out crop rotation and stubble
In order to do a good job in crop rotation and stubble, we must first understand the vegetables involved in the crop rotation, their genetic relationships, and their biological classification. Belongs to that family.
1. Biological classification of vegetables
Among our common vegetables, vegetables such as cucumber, zucchini, bitter melon, loofah, melon, watermelon and other melons belong to the Cucurbitaceae; pak choi , Chinese cabbage, cabbage, cauliflower, broccoli, radish, etc. belong to the cruciferous family; solanaceous vegetables such as tomatoes, eggplants, peppers, and potatoes belong to the Solanaceae family; leguminous vegetables such as kidney beans, cowpeas, and snow peas belong to the Fabaceae family; carrots, Celery, coriander, and fennel belong to the Apiaceae family; leeks, garlic, scallions, onions and other onion and garlic vegetables belong to the Liliaceae family; lettuce, chrysanthemum, chicory, and artichokes belong to the Asteraceae family; mint, nepeta, basil, perilla, etc. Fragrant leafy vegetables belong to the Lamiaceae family; spinach belongs to the Chenopodiaceae family.
2. Principles that should be followed in crop rotation
With these, we can easily create a crop rotation system.
But to develop an efficient crop rotation system, in addition to choosing vegetables belonging to different families and genera for crop rotation, we also need to pay attention to the following principles:
(1) Try to choose vegetables with fewer pests and diseases to participate in the crop rotation
Onions and garlic vegetables and some vegetables with special aromas, such as celery, coriander, nepeta, perilla, fennel, spinach, chrysanthemum, mint, etc., have fewer pests and diseases. They should be compared with melon vegetables. , solanaceous vegetables, Chinese cabbage, cauliflower and other vegetables with more pests and diseases should be rotated and cropped.
(2) Nutrient-consuming vegetables should be rotated with land-growing vegetables
Leguminous vegetables such as kidney beans, cowpeas, and snow peas are more drought-resistant than other vegetable types. Rhizobium bacteria can fix nitrogen in the air and improve the physical structure of the soil. They are land-growing vegetables. Their participation in crop rotation is beneficial to fertilizing the soil.
(3) Vegetables that require more fertilizer should be rotated with vegetables that require less fertilizer.
For example, green onions, garlic, leeks, onions, etc. have weak roots and absorb nutrients from the soil. There are fewer nutrients, leaving more nutrients for subsequent crops. Therefore, they are good precursors to other vegetables, especially solanaceous and melon vegetables.
(4) Grain and vegetable rotation, flood and drought rotation
If conditions permit, grain and vegetable rotation, flood and drought rotation can also be carried out, which can effectively control soil-borne diseases.
In addition, you can also refer to several principles for crop rotation: match tall-stem vegetables with short-stem vegetables, such as tomatoes and spinach; match light-loving vegetables with shade-tolerant vegetables, such as watermelon and Strawberries; pair deep-rooted vegetables with shallow-rooted vegetables, such as cucumbers and cabbage; pair upright vegetables with creeping vegetables, such as peppers and strawberries; pair long-growing vegetables with short-growing vegetables, such as tomatoes and celery, Rapeseed, etc.
When appropriate, we can also repair sheds, which also have a good effect of reducing stubble, but due to the waste of light and heat resources and land, they are generally not used.
3. Crop rotation time
How long does it take to rotate a vegetable to avoid continuous cropping obstacles? This should be determined based on the occurrence of plant diseases and insect pests, the degree of resistance to continuous cropping, and the impact on soil fertility and other factors. Generally speaking, vegetables with serious soil-borne diseases and insect pests require a longer rotation time. Watermelons, muskmelons, tomatoes, cucumbers, winter melons, and eggplants are the least tolerant of continuous cropping. They are vegetables that avoid continuous cropping and generally require 3 to 4 crop rotations; beans, cowpeas, peppers, potatoes, Chinese cabbage, lettuce, green onions, onions, Garlic and other vegetables are not easy to be continuously cropped and generally need to be rotated for 2 to 3 crops; vegetables such as pumpkin, edamame, cabbage, cabbage, radish, cauliflower, celery, spinach, chrysanthemum and other vegetables are resistant to short-term continuous cropping and can be tolerated unless serious diseases occur. In this case, 1 to 2 crop rotations are enough, but additional base fertilizer must be applied.
When specifically arranging vegetable rotations, we need to comprehensively consider a variety of factors. A better rotation model needs to take into account both high-quality and high yields and market demand in order to obtain maximum economic benefits.