Can Chemical Fertilizers Be Used as Pesticides? Overapplication Harms the Soil
One of the biggest problems in agricultural production is the issue of pests, diseases and weeds. To prevent and control pests, diseases and weeds, pesticides are indispensable, and pesticides also have a certain toxicity, which affects both the environment and crops. So can chemical fertilizers be used as pesticides?
One of the biggest problems in agricultural production is the issue of pests, diseases and weeds. To prevent and control pests, diseases and weeds, pesticides are indispensable, and pesticides also have a certain toxicity, which affects both the environment and crops. So can chemical fertilizers be used as pesticides?
In fact, many fertilizers have killing and repellent effects on pests. Clever fertilization both increases soil fertility and prevents pests. It is good for human health, can prevent or reduce pests' resistance to pesticides, and can also protect the natural enemies of pests - truly killing several birds with one stone.
Below, the editor introduces several methods of using fertilizers instead of pesticides to control pests, for everyone's reference.
1. Phosphate fertilizer: Cotton bollworm is very sensitive to phosphorus during its egg-laying period and avoids it on contact. If a 2% superphosphate solution is sprayed during the cotton bollworm's egg-laying period, leaving 1 ridge unsprayed for every 5-6 ridges, the cotton bollworms can be driven to lay eggs in concentrated spots, making it easier to wipe them out all at once.
2. Nitrogen fertilizer: Urea, ammonium bicarbonate and ammonia water - these nitrogen fertilizers are volatile and have a certain irritating, corrosive and fumigating effect on pests. Using 250-800 grams of urea, plus 100 grams of washing powder, added to 150 kg of water and sprayed, can control pests such as red spider mites and aphids. Spraying a 1% ammonium bicarbonate solution during the pest outbreak period, once every 5-6 days, for 2-3 consecutive sprayings, has a marked effect on red spider mites, yellow spider mites, thrips, aphids and other pests with small bodies and weak tolerance, with a general kill rate of 80-90%. However, the concentration must be strictly controlled during use, and be sure to avoid too high a concentration, which can burn the crops.
3. Plant ash: That is, the residual ash after burning firewood, fallen leaves, straw, rice husks, etc. It mainly contains calcium oxide and potassium carbonate, and is alkaline. The plant ash used as a substitute for pesticides must be dry and not damp when used. Generally, use 10-15 kg of plant ash per mu, soak it in 50-75 kg of clean water, take it out and filter it after 24 hours, and spray the filtrate, which can effectively control aphids. Using 20-30 kg of plant ash, applied in furrows or holes around the roots of vegetables and melons, has a very good effect on controlling root pests of scallions, garlic, chives, melons and other vegetables.
4. Lime: In the rainy season, leafy vegetables in low-lying vegetable plots with high ground temperature are prone to snail damage, and chemical control is generally ineffective. On a sunny day after the dew has dried, when the air humidity is relatively low, spread sifted dry fine lime powder on the soil surface between the vegetable rows. In this way, when snails crawl over the lime, powder sticks to their bodies, causing their soft bodies to dry out and die, with remarkable results. On cloudy and rainy days, the lime powder easily clumps into larger granules on contact with water, losing its adhesion and becoming ineffective, so a sunny day should be chosen.
5. Green vitriol: Its chemical name is ferrous sulfate. For farm households lacking plant ash, use 1 part green vitriol mixed with 3000 parts clean water, let it fully dissolve, then pour it at the roots or between the rows of scallions, garlic, chives and other crops; it can effectively kill root maggots, with a control effect of over 8%.
6. Silicon-calcium fertilizer: For crops such as corn and soybeans, applying 30-40 kg of silicon-calcium fertilizer per mu can avoid damage from corn borers and bean pod borers. For crops such as rice and wheat, applying 20-30 kg of silicon-calcium fertilizer per mu can greatly reduce damage from armyworms.
7. Mixed use of fertilizer and pesticide: Adding 50% dichlorvos emulsifiable concentrate (at a concentration of 1%) to a 1% urea solution and spraying it can kill red spider mites harming citrus, cotton and flowers. Using 50 grams of 40% dimethoate emulsifiable concentrate and 250 grams of urea per mu, added to 50 kg of water and sprayed during the booting stage of rice, can both control rice pests and promote increased rice yield. At the seedling stage and early flowering stage of soybeans, using 50 grams of ammonium molybdate and 50 kg of 50% phoxim emulsifiable concentrate per mu, added to 50 kg of water and sprayed, can control molybdenum deficiency in soybeans and also control aphids and bean pod borers.
8. Others: Mix 1 part fresh rabbit, sheep or cow manure with 5 parts clean water evenly, and on a sunny day pour it around the roots of peppers, eggplants, tomatoes, Chinese cabbage, green beans and other crops; it can effectively drive away cutworms, scarab beetles, mole crickets and other underground pests.
The harms of pesticides and chemical fertilizers:
Causing changes in soil pH. Superphosphate, ammonium sulfate, ammonium chloride and others are all biologically acidic fertilizers, meaning that after plants absorb the nutrient ions in the fertilizer, hydrogen ions in the soil increase, easily causing soil acidification.
Long-term large-scale application of chemical fertilizers, especially continuous application of a single type of chemical fertilizer, can lead to this situation within a short period. After soil acidification, it can cause the release of toxic substances, or increase the toxicity of toxic substances, producing adverse effects on living organisms.
Soil acidification can also dissolve some nutrients in the soil, which under the action of rainfall and irrigation seep downward to recharge groundwater, causing nutrient loss, making the soil barren, affecting crop growth, leading to soil compaction and declining fertility.
Applying large amounts of chemical fertilizers and using the land without nourishing it causes soil organic matter to decline. Chemical fertilizers cannot compensate for the lack of organic matter, further affecting the survival of soil microorganisms, not only destroying the soil fertility structure but also reducing fertilizer efficiency.
Harmful substances pollute the soil. The mineral raw materials and chemical raw materials used to make chemical fertilizers contain various heavy metals, radioactive substances and other harmful components, which enter the soil with fertilization and cause pollution.