In fact, fertile soil is not hard to find. As long as soil management methods are used well, there is hope to turn barren soil into fertile soil. As long as there is enough soil fertility, choose crops and varieties that adapt to the climate in this area, and good planting management methods, it is not difficult to obtain high yield. The following are eight common dimensions of soil problems, from the occurrence of problems to how to diagnose and how to repair them, which are explained as follows:
1. Improper soil pH and soil acidification
(1) Reasons for the problem: Some soils that are too acidic (below 5.0) or too alkaline (above 7.5) tend to make the plant nutrients in the soil ineffective, making crops unable to adapt, especially soil acidification is the most common in our farming, which is not caused by a large amount of rainwater leaching and parent material acidity, plants absorbing a large amount of positive ion nutrients, improper application of too many acidic fertilizers and too many organic acids, and the soil buffering capacity is poor.
(2) Diagnosis of soil pH value: Commonly used methods are pH electrode method and litmus test paper color method. When determining pH value, soil should be mixed with water before determination, and it cannot be determined in dry soil, because determining soil pH value is to determine the concentration of hydrogen ions in aqueous solution.
(3) Solutions to 3)pH discomfort:
Application of neutralizer: alkaline substances such as lime (such as agricultural lime, dolomite powder, etc. ) should be applied to acidic soil, and organic matter should be applied to the neutralized soil. Acidic substances (such as sulfur powder, dilute sulfuric acid, etc. ) should be used in alkaline soil, but the soil should not be over-neutralized, which can be improved by gradually neutralizing year by year. The application of organic substances in acidic soil or alkaline earth contributes to the availability of various nutrients. Emergency foliar fertilizer can temporarily improve the properties of soil that is over-acidic or over-alkaline, which is a temporary solution but not a permanent cure. Thoroughly improving the soil is the permanent cure. Second, the soil organic matter is lacking.
(1) Cause of the problem: In rainy, high temperature and humid environment, soil organic matter decomposes rapidly, especially on the hillside. In China, the soil in most areas is short of organic matter. When the soil is short of organic matter, the amount of chemical fertilizer applied by farmers will increase, resulting in waste and even inability to produce crops. Instead, it will increase soil diseases and cause great pollution to the environment. To change this situation, we must start with increasing soil organic matter, so as to get twice the result with half the effort. Pay special attention to the protection of soil organic matter, because soil organic matter has many benefits:
Improve soil physical properties: improve soil aggregate structure, make soil soft and promote ventilation and drainage. Increase soil water retention capacity. Slowly release the nutrients needed by plants. Clamping micronutrients can help the dissolution of plant nutrients. Increase the buffering capacity of soil and alleviate the acid-base reaction of soil. Absorb and exchange plant nutrients, improve the slow release performance of fertilizer. Provide rich food for soil beneficial microorganisms, so that soil microorganisms can resist a large number of germs. Reduce man-made or natural toxic substances and their functions. Some ingredients help plants grow. It can reduce the sharp change of soil temperature. It can be seen from the above that in order to realize the above ten functions, it is necessary to improve the content of soil organic matter.
(2) Diagnosis method of organic matter deficiency: In addition to the analysis of soil organic matter content by professional agricultural technology departments, it can also be observed by naked eyes. For example, the soil is hard after drying, or the color is very red and yellow, and there is no granular structure. These are all characteristics of lack of organic matter.
(3) Solutions to the lack of organic matter: applying organic fertilizer to increase the source of soil organic matter, or planting green manure crops. Rotation should be adopted in planting, especially leguminous rotation is most beneficial to improve soil organic matter. In management, it is necessary to increase the use of plastic film and reduce soil erosion and topsoil loss, which is also one of the methods to maintain soil organic matter. In recent years, the application of humic acid and peat soil is also very helpful to the increase and stability of soil organic matter.
Third, the physical properties of soil are poor.
(1) Cause of the problem: The soil is acidic. When it lacks organic matter, its physical properties are poor, its aggregate structure needs to be improved, its water-holding capacity is poor, it is easy to dry, and it is particularly hard when it is dry. This is a typical barren soil. Too thick or too sticky soil can also constitute problem soil. If it is too thick, the water retention is poor; Too sticky soil is too dense and the drainage is not smooth, resulting in poor root growth.
(2) The method to diagnose the poor physical properties of soil: touch and grade by hand to judge whether it is too sticky or too sandy; Observe whether the soil pores are too dense. When touching by feeling, take a small amount of soil sample, wet it with water and rub it, which is sandy soil with gravel feeling; Very sticky, but can be kneaded into strips, containing more sticky particles. The porosity of soil and the structure of clods or aggregates can be easily observed with naked eyes.
(3) Solve the problem of poor physical properties of soil:
Poor drainage: The economical method for poor regional drainage is to choose water-resistant crops or varieties, or plant them on high ridges. The drainage system can adopt simple drainage or pipeline drainage method, and the construction of drainage system should pay special attention to the economic benefits of drainage efficiency and service life. Poor soil structure: poor soil porosity or aggregate structure, generally by adding organic matter, with lime. For soils with strong alkalinity, only organic matter can be applied. For deep soil improvement, deep soil can be loosened by deep tillage or fertilization. The soil is too sandy or sticky: In addition to selecting crops or varieties that can adapt to this bad soil, foreign soil and organic matter can be used to improve this bad texture. Fourth, the soil nutrients are unbalanced.
(1) Cause of the problem: Unbalanced or excessive application of chemical fertilizers will lead to antagonistic absorption among nutrient elements, regardless of large, medium and trace elements, which can be excessive. For example, crops with excessive nitrogen are prone to deficiency and cold, lush foliage, easy to get sick, and difficult to bloom or set fruit.
(2) Diagnosis of nutrient imbalance: The nutrient imbalance in soil is invisible to the naked eye, but it can be known through plant growth observation, or through phytochemical analysis combined with soil analysis and diagnosis. Soil should also be analyzed and diagnosed regularly, which is as important as physical examination, especially in the intensive cultivation system, which needs to be diagnosed at least once every three or four years.
(3) The key to solve the imbalance of soil nutrients:
Understand the characteristics of crop varieties: because various crops have different nutrient requirements for soil, we must first understand the fertilizer requirements of crop varieties. In the process of growth, the deficiency of nutrients is supplemented by leaves. Then improve the soil properties, such as acid-base discomfort can be adjusted to balance nutrient absorption. If it is caused by excessive and unbalanced nutrients, it will take a long time to improve. Organic matter with high maturity (such as compost and humus peat soil) can be used for adsorption to reduce excessive harm and control it in a balanced state. Cooperative rotation system: the soil nutrients are unbalanced, and different rotation crops can absorb a lot of nutrients to reduce the harm to the soil, so as to achieve a state of nutrient balance, and with appropriate fertilization, the deficiency of soil nutrient imbalance can be improved. Balanced fertilization: When paddy field rotation cannot be carried out on the hillside, it is unrealistic to only rely on rainwater to leach excessive nutrients. In addition to the above-mentioned organic matter with high maturity, it can also be remedied by excessive antagonistic elements, such as the lack of trace elements caused by excessive phosphorus, that is, deep irrigation fertilization or foliar fertilization; If excessive potassium fertilizer is easy to cause magnesium deficiency, magnesium fertilizer such as magnesium sulfate or magnesium silicate should be used as a counterweight to greatly reduce the harm caused by excessive nutrients. Five, salt and heavy metal accumulation and pollution
(1) Cause of the problem: Pollution, improper irrigation water or excessive use of chemical fertilizers will all cause the accumulation of soil salt and heavy metals. Because soil has adsorption capacity, it is the result of long-term accumulation.
(2) Diagnosis of salt accumulation and heavy metal pollution: The most accurate thing is to determine the content of salt and heavy metals through chemical analysis. The accumulation of salt can also be observed with the naked eye. White powder or crystalline salts can be observed in the sun-dried topsoil during diagnosis, and white material will appear when the salt accumulates too much.
(3) Solving salt accumulation and heavy metal pollution: the accumulation caused by the application of a large amount of salt fertilizer in intensive cultivation of crops can be rotated in dry fields and paddy fields, and a large amount of soluble salts can be washed away in paddy fields; Or choose more salt-tolerant crops, because the salt tolerance of crops is different; The application of organic matter is also helpful for salt washing, because organic acids decomposed by organic matter can increase the solubility of salt. Heavy metal accumulation pollution can be absorbed by organic matter and reduced by dilution; If the pollution is serious, food crops or feed crops should not be planted to avoid pollution entering the human food chain; If you want to plant, you need to carefully choose non-edible plants, such as forest plants and fiber-specific crops.
Six, the problem of topsoil loss
(1) Cause of the problem: Topsoil is a valuable soil that has been naturally improved for many years. When a hillside lacks surface plant protection, the excellent topsoil is very thin and most of it will be washed away. The loss of topsoil is accompanied by the loss of fertilizer.
(2) Diagnosis of topsoil loss: This is quite easy to judge. As long as you look at whether the water flowing out of the rain is turbid or turbid, you can know whether the topsoil is lost.
(3) Solution of topsoil loss: Topsoil should be protected by covering or planting grass, especially planting grass in orchard is the most effective, and weeding is not needed in rainy season. On the surface, grass will absorb the fertilizer applied by competitors, but after the inhaled fertilizer is cut, covered or ploughed, it will return to the soil, which is very helpful for the topsoil fertility of perennial fruit trees. Planting grass can also make rainwater penetrate into the soil layer, increase organic matter and change the soil.
Seven. Soil diseases and insect pests
(1) Cause of the problem: There are many factors that cause soil diseases and insect pests, and it is easy to cause crop root diseases due to the propagation of pathogenic bacteria or the reduction of plant disease resistance. The occurrence of soil diseases is closely related to climate environment and irrigation water sources. The infectious bacteria of seedlings can not be ignored, and healthy seedling raising is very important.
(2) Diagnosis of soil diseases and insect pests: In order to accurately understand root diseases and identify pathogen species, special identification methods are needed. The causes of root death may be caused by biological or abiotic factors, or they may be mutually causal. The harm of nematodes to the root system is easy to observe, and the root system will have swelling, swelling or tumor-like symptoms.
(3) Solutions to soil diseases and insect pests: The treatment of soil diseases and insect pests includes chemical treatment, physical treatment (such as high temperature) and biological treatment. In addition, soil improvers can improve soil by chemical, physical, biological and other different ways, making pests and diseases difficult to reproduce or increasing crop resistance, so as to achieve the purpose of controlling soil pests and diseases. For example, applying organic matter or biological bacterial fertilizer to improve soil can also reduce the occurrence of soil diseases, but it should be noted that if the organic matter in feces is not decomposed, it is likely to cause many bacterial or insect infections.
Eight, continuous cropping soil problems
(1) Cause of the problem: The problem soil caused by continuous cropping is generally nothing more than a physical, chemical or biological problem in the soil, which is usually caused by the overgrowth of bacteria or worms, the accumulation of toxic substances and salts or the imbalance of nutrients.
(2) Diagnosis of continuous cropping: After continuous cropping, one or similar crops will have poor growth, which cannot be completely improved by fertilization, such as seedling withering and root rot. The growing point or new leaf is abnormal or does not stretch.
(3) To solve the problem of continuous cropping soil: it is best to take crop rotation, especially in dry and paddy fields. Organic matter can be used to improve or grow green manure. Organic matter can adsorb and decompose toxic substances and balance harmful microorganisms in soil. In addition, supplementing macronutrients, macronutrients and micronutrients can reduce the nutritional imbalance. Microbial fertilizers can also be used. Continuous cropping fields often have a large number of aboveground or underground roots, and these residues may also be the root of the problem. Therefore, clearing the residue in the field can reduce the harm of toxic substances or pests and diseases.
The above eight common problems do not exist in all soils. Therefore, we must first understand the characteristics of soil, determine where the problem lies, and then solve the problem. The fertility of soil will naturally change. With healthy soil, there will be healthy crops. As long as you are diligent in management and keep the soil fertile, the high yield of crops is close at hand.