How to choose and scientifically apply chemical fertilizers? These little common-sense tips are worth knowing

Chemical fertilizer refers to fertilizer made by chemical methods or by mining ore and processing it. It is also called inorganic fertilizer, and includes nitrogen fertilizer, phosphate fertilizer, potash fertilizer, micro-element fertilizer, compound fertilizer, and so on. So how should chemical fertilizers be chosen? Below, the editor will explain in detail some little common-sense tips on choosing and scientifically applying chemical fertilizers.

I. How to choose a good compound fertilizer

1. Choose products made by legitimate manufacturers

This is because legitimate manufacturers have very advanced production equipment and production technology, and the products they make have uniform granules, balanced nutrients, and stable quality. Moreover, the product formulas are developed by experts through long-term trials based on soil nutrient conditions and crop characteristics, with reasonable formulas, strong targeted effect, complete nutrients, and sufficient content, so they can be used with confidence.

2. Choose compound fertilizer reasonably according to local soil conditions

Fertilizers are divided into acidic and alkaline types, and soils are the same. For example, for saline-alkali land, an acidic compound fertilizer whose nitrogen source is ammonium nitrate should be chosen. It can not only supply the nutrients needed by crops, but also reduce soil alkalinity. At the same time, it also avoids the adverse effects of “chlorine damage” and “salt damage” on crops.

3. When choosing compound fertilizer, be sure to calculate the input-to-output ratio well

When choosing compound fertilizer, be sure to calculate the input-to-output ratio well and choose compound fertilizer with a reasonable price. This is because the key issue in increasing agricultural production and income lies in lowering agricultural costs. Choosing a fertilizer with good quality and a reasonable price is very important; otherwise, the loss will outweigh the gain.

II. What issues should be noted when applying compound fertilizer

1. Compound fertilizer is generally used as base fertilizer or seed fertilizer

When used as base fertilizer, before sowing, apply it during land preparation, generally to 10-20 cm below the plow layer; when used as seed fertilizer, be sure to keep fertilizer separated from seeds, generally applying it 5-6 cm below the plow layer.

2. Fertilization should be reasonable

Applying compound fertilizer does not mean the more the better. Blindly applying too much compound fertilizer not only increases costs, but also easily causes problems such as burning seeds and burning seedlings, affecting the crop's reasonable absorption of nutrients. When using it, be sure to follow the product instructions and, at the same time, calculate a reasonable fertilization amount based on the past fertilization amount in the local area.

3. Applying compound fertilizer is not once and for all

This is because although compound fertilizer can largely meet the crop's needs for various nutrients during growth and development, during rapid growth periods such as the heading and grain-filling stages, the demand for nitrogen is very large, and nitrogen fertilizer must be topdressed as appropriate. Otherwise, it will have a great impact on yield, even if the nitrogen raw material of the compound fertilizer is long-acting urea.

III. How to prevent misunderstandings in chemical fertilizer application

Some farmers, when fertilizing crops, use fertilizer improperly or with inadequate techniques, resulting in low fertilizer use efficiency, increased fertilization costs, and even crop damage leading to reduced income.

Misunderstanding one: using calcium magnesium phosphate fertilizer as topdressing. Calcium magnesium phosphate fertilizer is not easily dissolved in water and has a slow fertilizer effect. When used as topdressing, especially after the middle stage of crop growth, its use efficiency is relatively low and the effect is also poor. The correct application method is: calcium magnesium phosphate fertilizer can only be applied as base fertilizer mixed with organic fertilizer, and it also has a good effect when used as seed dressing fertilizer.

Misunderstanding two: shallow application, broadcast application, or excessively high concentration application of nitrogen fertilizers such as urea and ammonium bicarbonate. Urea is an amide-form nitrogen fertilizer with relatively high nitrogen content. After being applied to the soil, apart from a small amount being directly absorbed and used by plants, most must be transformed into ammonium nitrogen through the action of urease secreted by microorganisms before it can be absorbed and used by crops. Ammonium bicarbonate is unstable in nature, and shallow application on the surface has low use efficiency. At the same time, shallow topdressing of nitrogen fertilizer in large amounts and at excessively high concentration can cause the volatilized ammonia gas to scorch crop stems and leaves, causing fertilizer damage. The correct application method is: nitrogen fertilizer used as topdressing should be applied in furrows or holes, at a depth of 5-10 cm, and covered with soil after application. When used as foliar fertilizer spray, the concentration should be well controlled. For wheat, rice, cotton, corn, and so on, 0.8%-1% is suitable; for vegetables, the spray concentration should be lower.

Misunderstanding three: directly mixing seeds with superphosphate. Superphosphate contains 3.5%-5% free acid and is highly corrosive. Directly mixing it with seeds will reduce the seed germination rate and seedling emergence rate. The correct application method is: when used as topdressing, it should be applied deeply in furrows. When used as seed fertilizer, it should be applied 5-6 cm below or beside the seeds, using soil to separate the fertilizer from the seeds.

Misunderstanding four: mixing zinc fertilizer and phosphate fertilizer for application. Because there is a serious “antagonistic effect” between zinc and phosphorus, if zinc sulfate is mixed with superphosphate for application, the fertilizer effect of zinc sulfate can be inhibited to a large extent, reducing its effectiveness. The correct application method is: zinc fertilizer and phosphate fertilizer should be applied separately. Phosphate fertilizer as base fertilizer and zinc fertilizer as seedling fertilizer, or zinc fertilizer as base fertilizer and phosphate fertilizer as seedling fertilizer. In this way, the fertilizer effects of phosphorus and zinc fertilizers can be improved.

Misunderstanding five: dissolving borax in cold water for spray application. After borax is dissolved in cold water, “recrystallization” quickly occurs, causing the borax solution to precipitate out and lose its fertilizer effect. The correct application method: first put boron fertilizer into a thermos bottle, add boiling water to dissolve it, tightly close the stopper and bring it to the field, then add cold water to the required concentration. The effect will be greatly improved.

IV. Six misunderstandings in urea application

Urea contains 46% nitrogen and is a high-quality chemical nitrogen fertilizer used relatively often in rural areas. According to the author's understanding, some farmer friends are still not very clear about the properties of urea and still have the following six misunderstandings when using it.

Misunderstanding one: mixing urea with ammonium bicarbonate. After urea is applied to the soil, it must be converted into ammonia before it can be absorbed by crops, and its conversion speed under alkaline conditions is much slower than under acidic conditions. After ammonium bicarbonate is applied to the soil, it shows an alkaline reaction, with a pH of 8.2-8.4. Mixed application of ammonium bicarbonate and urea in farmland will greatly slow the speed at which urea is converted into ammonia, easily causing loss of urea through leaching and volatilization. Therefore, urea and ammonium bicarbonate should not be mixed or applied at the same time.

Misunderstanding two: broadcast application on the soil surface. When urea is broadcast on the soil surface, at room temperature it takes 3-5 days of conversion before it can be absorbed by crops. Most of the nitrogen is volatilized during the process of urea converting into ammonium, and the use efficiency is only about 30%. If broadcast on alkaline soil, nitrogen loss is even faster and greater. Therefore, nitrogen should not be broadcast on the soil surface.

Misunderstanding three: using urea as seed fertilizer. During the production process, urea often produces a small amount of biuret. If the biuret content exceeds 2%, it will poison seeds and seedlings. When urea enters seeds and seedlings, it can denature proteins and affect seed germination and seedling growth.

Misunderstanding four: irrigating immediately after applying urea. Urea is an amide-form nitrogen fertilizer, and after application it must be converted into ammonium nitrogen before it can be absorbed and used by crops. The conversion process varies in duration depending on soil quality, moisture, temperature, and other conditions, generally taking 2-10 days to complete. If irrigation or drainage is carried out immediately after urea application, or if it is applied before heavy rain in dryland, the urea will dissolve in water and be lost.

Misunderstanding five: mixing urea with alkaline fertilizers. After urea is applied, it must be converted into ammonium nitrogen before it can be absorbed and used by crops in large amounts. Under alkaline conditions, most of the ammonium nitrogen will become ammonia gas and volatilize. Therefore, urea cannot be mixed or used at the same time with alkaline fertilizers such as lime, plant ash, and calcium magnesium phosphate fertilizer.

Misunderstanding six: applying urea to celery. Celery needs a large amount of nitrogen fertilizer as topdressing throughout its growth period, but urea must not be applied. This is because topdressing with urea increases celery fiber and makes it thicker, causes plant aging and slow growth, and gives it a bitter taste when eaten, resulting in poor quality. Celery is suitable for application of ammonium bicarbonate, ammonia water, and organic fertilizers, which helps improve quality.

V. Series of knowledge on balanced fertilization

1. What is balanced fertilization

Balanced fertilization means that all crop plants can reasonably absorb, in certain proportions and amounts, the various nutrients needed for their healthy growth. It also means maintaining a balance between the nutrients crops obtain from the soil and the nutrients returned to the soil through fertilization, air, and water, so that crops are high-yielding and the soil does not become exhausted.

2. How to carry out balanced fertilization

The purpose of producing and using compound fertilizer is to meet the requirements of scientific fertilization and economical fertilization in agriculture and to achieve balanced fertilization. Because using compound fertilizer can save the costs of storage, transportation, and application, achieve reasonable fertilizer formulas, and ensure yield-increasing effects, especially special compound fertilizers produced for local soil nutrients and crop varieties, the effect is even better. Therefore, choosing a suitable special compound fertilizer is the key to achieving balanced fertilization and is also an important measure for developing high-yield, high-quality, and high-efficiency agriculture.

3. What effects can balanced fertilization bring

Because the proportions and amounts of various nutrients in balanced fertilization are reasonable, it can reduce fertilization costs; balanced nutrient absorption makes plants robust, strengthens their ability to resist pests, diseases, and drought, and naturally gives crops high yields and a bumper harvest.