Different soil types require different fertilization methods

?Clay soil

Generally speaking, clay soil has a high organic matter content and a strong ability to retain nutrients, so nutrients are not easily lost. However, it has poor permeability, and after fertilization the nutrients are released slowly, making it difficult for crops to take root. People often say this kind of soil "nourishes old seedlings but not young ones." This soil is cold in nature, and organic matter decomposes and mineralizes slowly, so fully decomposed farmyard manure should be applied, preferably hot manures such as horse manure and sheep manure as a base fertilizer.

When applying chemical fertilizers, because the soil has a large buffering capacity and a strong ability to retain nutrients, applying a larger amount at one time will not cause seedling burn or nutrient loss. When topdressing chemical fertilizers, it should be done appropriately earlier, and it is advisable to "eat more, in smaller meals," appropriately reducing the number of applications. However, nitrogen fertilizer should not be applied in excess, lest the fertilizer effect be overly exerted later, causing crops to stay green and mature late, leading to reduced yields.

Clay soil has a heavy, sticky texture and a strong ability to adsorb and fix nutrients, and the diffusion rate of nutrients in the soil solution is slow. Therefore, attention should be paid to the placement of chemical fertilizers. For example, phosphate and potassium fertilizers should be placed as close to the root system as possible, and timely hoeing and loosening of the soil should be carried out to enhance soil permeability. Attention should also be paid to timely watering, using water to regulate fertilizer, so as to improve fertilizer efficiency.

Sandy soil

Sandy soil has a loose texture and many coarse particles, contains few soil nutrients, and does not retain water or fertilizer. It is advisable to apply more farmyard manure and organic fertilizer, or return straw to the field, or plant green manure crops and plow them under at the right time, so as to build up soil fertility and improve the soil structure year by year.

When applying chemical fertilizers, a large amount should not be applied at one time, as a large amount is easily lost. The principle of small amounts applied multiple times should be adopted, and fertilizers with low leaching loss should be used, such as ammonium nitrogen and potassium fertilizer. For chemical fertilizers, it is best to use concentrated application methods such as furrow application or hole application. To improve sandy soil, a method of mixing in soil while fertilizing can also be used, which both preserves nutrients and improves sandy soil. Organic fertilizers should be applied deeply, because shallow application makes them difficult to decompose or causes them to decompose too quickly. For sandy soil, it is advisable to use cold manures such as cow manure and pig manure as a base fertilizer, so that the soil quality gradually improves.

????Loam soil

Loam soil is a soil with relatively good agronomic properties. Its permeability, water- and fertilizer-retention capacity, and potential nutrient content fall between those of sandy soil and clay soil. It is suitable for the growth of all kinds of crops, and generally fertilization can be carried out at the right time and in the right amount according to yield requirements and the crop's growth period.

In principle, long-acting fertilizers should be combined with short-acting fertilizers, organic fertilizers with chemical fertilizers, macroelement fertilizers with medium- and microelement fertilizers, and nitrogen, phosphorus, and potassium fertilizers combined with one another.

Paddy fields and dry land

In paddy fields, because of the movement of water, nutrients in the solution are carried away, making it difficult for the applied fertilizers to accumulate in the soil and causing nutrient deficiency. At the same time, the water in the soil can also dilute the applied fertilizers, so even fertilizing near the crop roots will not harm the crop root system. When applying chlorine-containing fertilizers such as ammonium chloride and potassium chloride in paddy fields, there is also no need to worry about the accumulation of chloride ions in the soil. However, because paddy fields have a water layer, they easily cause soil oxygen deficiency, and under conditions of insufficient oxygen supply, some organic and inorganic toxic substances are produced. For example, applied organic fertilizers will accumulate organic acids under anaerobic decomposition conditions.

Therefore, when choosing organic fertilizers for paddy fields, attention should be paid to selecting fully decomposed organic fertilizers, otherwise too many reducing substances will be produced. At the same time, due to the vigorous activity of anaerobic bacteria, the consumption of oxygen in the water will also increase, further aggravating soil oxygen deficiency and causing damage to the crop root system. In paddy fields, some organic substances, such as nitrogen, sulfur, iron, and manganese, exist in low-valence forms, that is, nitrogen as nitrous acid, iron as ferrous iron, manganese as manganous manganese, and sulfur as hydrogen sulfide. Therefore, when applying nitrogen fertilizer in paddy fields, it is not advisable to choose fertilizers such as nitrates and potassium sulfate. This is because the former is the most easily dissolved nutrient and the fastest moving in water; besides being easily leached, it also easily forms toxic nitrites and causes denitrification, resulting in nitrogen loss. Applying ammonium fertilizer in paddy fields, however, can fully exert its fertilizer effect because it is relatively stable.

Dry land is the opposite of paddy fields. Fertilization on dry land not only does not cause nutrient leaching, but also allows nutrients to gradually accumulate in the soil, and it easily causes the salt concentration to become too high. Therefore, on dry land, fertilizing near the plant root area must be avoided.

At the same time, because sulfate radicals react with calcium hydroxide and calcium carbonate in the soil solution, they can form poorly soluble calcium sulfate, which will not increase the soil salt concentration; while the chloride ions in potassium chloride can react with calcium sulfate in the soil to form water-soluble calcium chloride, increasing the salt concentration of the soil solution. Furthermore, dry land does not easily produce denitrification as paddy fields do. In addition, crops that prefer nitrate nitrogen should be planted more on dry land. Therefore, for dry land, choosing nitrates such as ammonium nitrate and compound fertilizers based on ammonium nitrate is relatively suitable.

Saline-alkali soil

Saline-alkali soil is the general term for saline soil and alkaline soil. Saline soil mainly refers to salinized soil with a relatively high content of chlorides or sulfates; the soil is alkaline, but the pH value is not necessarily very high. Alkaline soil refers to soil containing carbonates or heavy phosphates, with a pH value that is alkaline. Saline-alkali soil has little organic matter, low soil fertility, poor physical and chemical properties, and many harmful anions and cations to crops, making it difficult to promote seedling growth.

The fertilization principle for saline-alkali soil is to mainly apply organic fertilizers and high-efficiency compound fertilizers, and to control the use of low-concentration chemical fertilizers. Organic fertilizer contains a large amount of organic matter and can buffer the harmful anions and cations in the soil, which is conducive to root development and seedling preservation. High-efficiency compound fertilizer has few ineffective components and little residue, but the amount applied each time should not be too much, so as to avoid aggravating secondary salinization of the soil. After applying chemical fertilizers, irrigation should be carried out promptly to reduce the concentration of the soil solution.