The soil salinization of vegetable planting is serious, how to solve it effectively?

Soil degradation in vegetable fields is the most serious problem encountered in protected cultivation at present, which exists in almost all old sheds. The deterioration of vegetable soil includes three aspects: first, the deterioration of soil physical properties, which is manifested in hardening in production; Second, the deterioration of soil biological characteristics leads to imbalance of flora, which is characterized by high incidence of soil-borne diseases in production; The third is the deterioration of soil chemical properties, which is manifested in soil acidification and salinization in production. Among all these problems, soil salinization is the most prominent. Therefore, how can we effectively reduce soil salinization? It is also an urgent problem to be solved in vegetable planting at present. The author combines many years of plant protection experience to tell you different solutions!

First, the harm of soil salinization in vegetable fields to vegetables

Salinization of vegetable soil refers to the high salt content in the surface soil, which means that the EC value (conductivity) is too high. The so-called EC value is a standard to measure the salt content of soil. If the EC value is too high, the absorption capacity of root system will be inhibited during the growth and development of vegetables, resulting in a series of developmental obstacles of vegetables. The harm of soil salinization in vegetable fields to vegetables is mainly manifested in the following three aspects:

1, harm to root system

Root system is the most harmful to vegetables, because the living environment of root system is soil. When the EC value is too high, when the concentration of salt ions in soil water is greater than that in root water, not only the absorption of nutrients and water by plant roots is inhibited, but also the roots lose water under osmosis. In production, retting and root system aging will be shown.

The root system of vegetables is in dynamic balance, and new roots are constantly produced and aged. In the early stage, the growth of new roots was much greater than that of aging, so the growth performance was relatively strong. However, when soil salinization is serious, root system aging will accelerate. Our most intuitive feeling is premature senescence of seedlings. All premature senility has its roots.

2. Damage to leaves

After serious salinization of vegetable soil, as we said earlier, it will affect the absorption of water and nutrients by roots. Most of the leaves of vegetables show yellow leaves in Phnom Penh, which is actually a manifestation of leaf aging. And it starts from the lower leaves of plants and gradually spreads upward. It should be noted that root diseases can also cause leaf yellowing, but salinization is also a major cause.

In actual cultivation, we see that some leaves are black, green, black and green, but they are broken when rubbed. This phenomenon is mostly due to excessive application of nitrogen fertilizer and hormones leading to leaf aging. Normal leaves are bright green and shiny, just like being coated with oil. After rubbing by hand, it still unfolds naturally and has better toughness, rather than the dark green we imagined.

3. Harm to fruits

Soil salinization is particularly harmful to colored vegetables. Problems such as slow discoloration, chromatic aberration and late maturity are directly related to soil salinization. Due to the damage of salinization to roots and leaves, the absorption capacity of nutrients is inhibited and the accumulation of photosynthetic products is weakened. When encountering the above problems, we must first investigate our soil problems.

2. Where does the salt in soil salinization come from?

To reduce the harm of soil salinization, we must first understand the source of salt in salinization, so as to fundamentally solve the problem.

1, irrigation water

Excessive salt concentration in irrigation water is an important factor leading to soil salinization. Most of our irrigation water uses shallow water and salt water. The research shows that the EC value of shallow water and salt water is much higher than that of deep well water. After irrigation with irrigation water with high EC value, salt will accumulate in the soil and accelerate the formation of soil salinization.

In addition, the salt tolerance of different crops to saturated soil solution and irrigation water is completely different. For example, when the EC value of soil saturated solution is 4.7, it has no effect on the growth of watermelon, melon and other crops, but it will cause serious harm to tomatoes and cucumbers. Similarly, when the EC value of irrigation water is 3. 1

2. Fertilizers applied

Excessive fertilization is the main cause of soil salinization. Including chemical fertilizer and our usual manure.

(1), excessive application of chemical fertilizer.

The use of chemical fertilizer is a double-edged sword, which has obvious effects on increasing yield and improving quality, that is to say, appropriate dosage is beneficial to the growth of vegetables, but the more it is used, the higher the yield will be. Exceeding the critical value will not only increase production but also reduce production. Because all fertilizers are chemical synthetic fertilizers, whether it is our urea, diammonium phosphate, potassium sulfate, potassium chloride, etc. , are inorganic salts. Multi-purpose, abuse, vegetables can not be absorbed, long-term accumulation, forming soil salinization.

(2) Fertilizer

This is the last thing we vegetable farmers can understand. Many experts have emphasized that manure should be used as much as possible, because manure is the best organic fertilizer. It's right to keep livestock at home, but we ignore the premise that most chickens, cattle and sheep are farmed on a large scale. The main food source of these livestock and poultry is feed, and the most inseparable component in feed is salt. If you don't believe me, you can visit the farm and see the salt added in the feed, and you will understand why we don't recommend using manure in vegetable planting.

Therefore, it is not recommended to use the feces obtained from large-scale farming of livestock fed with feed. No matter how you ferment, salt still exists, because it won't volatilize and fix. Unless desalting, there are desalting devices in the process of manure fermentation in Japan, Europe and other western countries, but there is basically no such treatment in China. Of course, the manure produced by our own livestock can be fully utilized. We all know the importance of organic fertilizer to vegetable production, so manure can't be used. What should we use? Don't worry, I will mention the substitution of manure in the mitigation measures of salinization later.

Third, measures to reduce soil salinization in vegetable fields.

Only after finding the source of salinization salt in vegetable fields can we put forward targeted solutions.

1, vegetable field with less soil salinization.

For vegetable fields where soil salinization is not very serious, we need to improve our water and fertilizer management habits to keep the soil free of excess salt.

(1) to improve the quality of irrigation water.

When hydrating vegetables, try to use deep well water for irrigation, and try to use water. If we have to use water with high EC value, we need to take some measures to improve the water quality and minimize the influence of salt content on vegetables, such as adding some fertilizers containing good amino acids when watering, improving the salt tolerance of crops and reducing the stimulation of salt ions on vegetable crops.

(2) Using manure substitutes to supplement soil organic matter.

What to supplement soil organic matter without manure is the most concerned topic for most vegetable farmers. The answer is that it is better to use straw materials, including peanut shells, mushroom sticks and rice husks. , as well as corn, wheat and other ordinary straw, 3~5 square meters per mu. It should be noted that if straw is used, it can only be used after adding bacteria and water for suffocation fermentation and decomposition.

(3) Rational application of chemical fertilizers

Under the condition of modern technology, it is impossible not to use chemical fertilizer, even in the Netherlands, the most developed country in agriculture in the world. Growing vegetables is inseparable from nitrogen, phosphorus and potassium, which is what we often call chemical fertilizer. The problem now is that we are applying too much fertilizer, not lacking fertilizer, but that our vegetables simply can't absorb so much. If we want to use organic fertilizer instead of chemical fertilizer, the input-output ratio is unbearable for our vegetable farmers.

The only way out is to use less, lose weight and increase efficiency, which is also the original intention of our country to put forward zero growth of chemical fertilizers and pesticides. Under the premise of ensuring the same yield, the less chemical fertilizer is used, the less damage to the soil environment will be. If you want to use less, you must improve the utilization rate of fertilizer. Under the current technical conditions, it is a good choice to use water-soluble fertilizer for topdressing. At present, the utilization rate of compound fertilizer in China is basically around 30%, while the utilization rate of water-soluble fertilizer can reach 50%~80% or even higher.

The research shows that the utilization rate of compound fertilizer is not 30% as we said, and the old vegetable shed over 7 years is only about 12%, and the rest is left in the soil, which is how soil salinization comes from. Therefore, it is suggested that compound fertilizer should only be used as base fertilizer. The concept that the more fertilizer is used, the higher the yield. Whether it is solid or liquid, we must use fertilizer well and use less fertilizer.

When using compound fertilizer as base fertilizer, the more the better, but the proportion should be appropriate. At present, 80% vegetable farmers use balanced ternary compound fertilizer when using compound fertilizer as base fertilizer, which is what we call fool fertilizer. What is suitable for planting and what is not suitable for planting. So what is the correct formula? It is suggested that low nitrogen (nutrient content 8~ 12), medium phosphorus (nutrient content 14~ 16) and high potassium (nutrient content 18~22) should be used as base fertilizers for fruits and vegetables. If the nitrogen content is high, the phenomenon of virtual growth will appear at seedling stage, which can be controlled by spraying drugs. For leafy vegetables, it is suggested to use high nitrogen (above 18 nutrient), low phosphorus (about 5 nutrient) and low potassium (about 5 nutrient), because leafy vegetables need nitrogen most, followed by calcium and potassium. Therefore, when applying base fertilizer, it is necessary to apply fertilizer according to the types of vegetables, and no matter what types of vegetables, a formula is used, which leads to excessive application of chemical fertilizer and incomplete absorption of vegetables, and leaving them in the soil will increase the salt in the soil.

2. Vegetable fields with serious soil salinization

For the old shed area where soil salinization has been serious, it is generally divided into three steps to control fertilizer first and then improve it:

Step 1: firstly, straw is used instead of feed to feed the feces. This can't be done. It's no use using more soil improvers. The salt content in straw is less, and the biggest advantage is that it can loosen the soil.

Step 2: Control fertilizer. Fertilizer control is the premise of soil improvement. If the amount of fertilizer can't be reduced, the salt can't be reduced, and there is no way to improve the soil. As mentioned earlier, how to control fertilizer is to use water-soluble fertilizer instead of compound fertilizer for topdressing.

Step 3: Cultivate bacteria and improve the soil. Amino acids, humic acid and alginic acid can only alleviate soil salinization, but can not improve soil salinization. What can really improve the soil is bacteria, that is, only the activities of bacteria can really improve the soil, such as biological fertilizer or microbial inoculum containing Bacillus subtilis.

It should be noted that many of our vegetable farmers use a lot of bacterial manure, but it has no effect. The problem is the survival of bacteria. Because bacteria can only improve the soil if they survive in the soil for more than one month, if we only apply bacterial fertilizer, our soil will be seriously deteriorated, and the survival time of bacteria is generally only 7~ 15 days. Therefore, when applying bacterial fertilizer, we must pay attention to adding flora conditioner, so as to ensure the survival of bacteria.

In the salinization improvement of vegetable soil, reducing the amount of chemical fertilizer and improving the utilization rate are the premise, and soil improvement is the ultimate goal. When the problem of salinization is solved, there will be fewer pests and diseases, and the yield and quality of vegetables will be improved a lot.