Apple tree nutrition diagnosis and scientific fertilization

　　 1 , the basic concept

　　 1 ) Sources of essential nutrients for fruit trees

The carbon, hydrogen, and oxygen required for fruit trees come from air and water, and the rest of the elements come from the soil. Therefore, in addition to carbon, hydrogen, and oxygen, plants mainly absorb these nutrients from the soil by roots .

　　 2 ) The shape of nutrients absorbed by fruit trees

Fruit trees mainly absorb inorganic ions in the soil, such as potassium ions, ammonium ions, nitrate ions, calcium ions, etc.; but they can also absorb certain soluble organic substances such as urea, amino acids, amides, nucleic acids and phosphoric acid. Main supply of fertilizer nutrient inorganic state ions, readily soluble in water, fertilizer soon; organic fertilizer nutrient supply both ionic state (decomposition) can form part of the organic nutrient supply.

　　 3 ) How fruit trees absorb nutrients

Crops absorb nutrients from the soil through the roots, but first the roots must be in contact with the nutrients, ie nutrients can be absorbed into the roots on the root surface. Nutrient How can we reach the root surface of it? One way is that the roots stretch directly to promote nutrients. This method is usually called interception. The nutrients intercepted by the roots are rare; the other is diffusion, that is, the nutrients move from the low concentration to the low concentration , and when the nutrient concentration near the root is higher than the root table, the nutrients spread to the root surface; approach is mass flow, i.e., mass flow, which is caused by the action of the leaf transpiration, transpiration consumed large amount of moisture near the root surface, is moved to cause the water around the roots, as it moves toward the water nutrient roots . The absorption of root nutrients by crops has two processes: active absorption and passive absorption. Passive absorption is a chemical physical process that does not require energy consumption , such as nutrients entering the cell through diffusion or charge balancing; active absorption is a process that consumes energy and is selective. Some people think that by passive absorption of nutrients into the free space (between the finger and the native cell wall membrane), the encounter called carrier material, carrier ions in the plasma membrane to the nutrient load in the cytoplasm, and the carrier is required energy Can work. Just as a car is a carrier, a car needs gasoline to move around. Therefore, if the plant supplies less energy to the roots, or if certain conditions affect the respiration of the roots and the lack of phosphorus, it will affect the absorption of nutrients by the plants.

　　 4 ) The purpose of rational fertilization

Reasonable fertilization requires that fertilization can achieve the following three objectives: 1 fertilization can enable plants to obtain high yield and quality; 2 obtain the best economic benefits with the least investment ; 3 improve soil conditions to create a good foundation for high yield and stability, that is, land use Combined with the land.

　　 5 ) The main basis for rational fertilization

The object of fertilization is mainly fruit trees. Therefore, fertilization must first consider the nutritional characteristics of fruit trees. Nutritional various crops are different, the same crop in different growth stages nutritional requirements are different. That is to say, different crops or crops have different requirements for the types, quantities and proportions of nutrients in different growth stages. Cereal crops and leafy vegetables require a lot of nitrogen , but legume crops require less nitrogen. Because they themselves have nodules to fix nitrogen in the air. Another example is that bananas require a lot of potassium, but they require less phosphorus. Therefore, crop nutrition characteristics are the most important basis for fertilization.

Secondly, fertilization mainly, so fertilization must be carried out according soil properties through, then the nature of the soil will inevitably affect the fertilization of the soils fed crop nutrition, wherein the main consideration is the amount of each nutrient in the soil, fertilizer supply and fertilizer And whether there are obstacles and so on.

Again, it is to consider the relationship between climate and fertilization, such as drought or dry season areas, regional and seasonal rain, cold and hot season how fertilization. In short, the climate affects the fertilization effect, and fertilization affects the adaptation and utilization of crops to climatic conditions. In addition, fertilization must be considered in conjunction with other agricultural technical measures.

　　 6 ) Do fertilizer utilization

Fertilizer utilization refers to the percentage of nutrients absorbed by the seasonal crops from the applied fertilizers as a percentage of the total nutrients in the fertilizer. The utilization rate can be obtained by field test and indoor chemical analysis according to the following formula:

Uptake in vivo fertilization crop area of the element of the element body subtracts crop fertilizer absorption zone divided by the total percentages of the value obtained by the feed element fertilizer.

In the current cultivation techniques management, utilization of fertilizer approximately in the range: Nitrogen of 30 - 50% phosphorus 10--15% potassium 40--70%.

　　 7 ) Nutrition critical period, critical value and maximum nutrient efficiency period

The nutrient critical period and maximum efficiency period of fruit trees are most closely related to fertilization effects. The critical period of nutrition refers to the amount of nutrients required by fruit trees during a certain growth period, although there are not many, but if there is a lack or excessive or imbalance between nutrients, it will have a significant adverse effect on crop growth and development. For most crops, the critical period generally occurs in the early growth stage, and the critical period of phosphorus occurs earlier, followed by nitrogen and later potassium. Therefore, phosphate fertilizer is commonly used as a seed fertilizer in production to ensure sufficient phosphorus in the early stage of crop growth.

Threshold is the nutrient content in the crop below a certain concentration, its growth or yield decreased significantly, and showed symptoms of nutrient deficiency, nutrient concentration in this case is called "nutritional critical" value.

Fertilizers applied at different times have great differences in the effect of increasing yield. One of the periods has a good nutritional effect of fertilizers. This period is called the maximum efficiency period of nutrition . That is to say, the economic output of each unit has the highest economic output. Maximum efficiency is often consistent with the period when crops require the most nutrients.

　　 2 , the four laws

　　 1 ) Equal importance law

CROP essential element in any quantity, are equally important, any one of the special features of nutrients not be instead of other elements, it is equally important legal and non-legal instead of nutrients.

　　 2 ) Minimum nutrient law

Fruit trees need to absorb various nutrients for growth and development. These nutrients, whether they are large amounts of elements or trace elements, are equally important. However, it is only the nutrient elements with the least relative content in the soil that limit the yield and quality of fruit trees. The yield and quality increase and improve with the increase of this nutrient within a certain limit. In production practice, if we can't find this limiting factor, it is difficult to increase the yield and quality of fruit trees even if we continue to provide other nutrients. Using a fruit tree fertilizer to meet the needs of this nutrient, then another relatively minimal content of nutrients will become an important factor limiting the yield and quality of fruit. This is the famous minimum nutrient rate.

The minimum nutrient rate was proposed by the German chemist Li Bixi. He once said: if the soil in a certain kind of essential nutrient deficiencies or lack of time, even if other nutrients are present, this soil will become barren. That is to say, the factor limiting production in a certain soil is one of the most inadequate nutrients. The minimum nutrient law reminds us find the lack of nutrients in crop yield in the most affected, as well as the proper relationship between the proportion of various nutrients in the fertilizer should be. The minimum nutrient is not fixed. After some minimum nutrient is solved, another nutrient may rise to the minimum nutrient.

In order to better illustrate the meaning of the minimum nutrient rate, it can be explained by the barrel principle. Production potential of fruit trees like a barrel around the city with a different width planks, when the ratio of the length of these boards are suitable, you can filled a bucket of water. If this surrounded stave different lengths, so that the number of barrels filled with water, is restricted shortest piece of wood, and water storage casks and how much of this as the only extended piece of wood and increase. When the plank is lengthened, another shorter plank will become a limiting factor in the storage capacity of the bucket. The law of minimum nutrient means that the yield is limited by the nutrient that is most lacking in the fruit tree . To some extent, the yield varies with the increase or decrease of this nutrient. In practice, the following points should be mastered: 1. The minimum nutrient refers to the least amount of soil in the soil, not the nutrient with the least absolute content in the soil ; 2. The minimum nutrient cannot be replaced by other nutrients, even if other nutrients increase. More, it can not increase production; 3 , the minimum nutrients are varied, it is the level of fruit tree production and the amount of fertilizer supply . It should be noted that the minimum nutrient rate applies not only to a large number of elements, but also to trace elements.

　　 3 ) Law of diminishing returns

The rate of reimbursement was first proposed by European economists Durgo and Anderson, reflecting the relationship between input and output in the absence of technical conditions . It means that the remuneration received from a certain land increases with the increase of labor and capital invested in the land, but the remuneration per unit of labor or capital is gradually decreasing as the input increases. For example, in fertilization, the effect of a certain nutrient is greater as it is less in the soil, but if the application amount of the nutrient is gradually increased, the yield per unit of nutrient is gradually reduced. Therefore, the amount of fertilizer obtained to obtain the highest yield is not necessarily the optimal amount of fertilizer, and the increase in yield will not increase the income due to the decline in economic benefits. So don't blindly increase the amount of fertilizer applied. According to the experiment, the optimal amount of fertilizer is about 5% less than the amount of fertilizer obtained to obtain the highest yield .

　　 4 ) Factor comprehensive action law

The growth and development of crops are affected by various factors ( water, fertilizer, gas, heat, light and other agricultural technical measures ) . Only under the premise that the external conditions ensure the normal growth and development of crops can the effect of fertilization be fully exerted. The central meaning of the comprehensive rate of factors is that crop yield is the result of the combined effects of factors affecting crop growth and development, but there must be a limiting factor that plays a leading role. Crop yield is limited to a certain extent by this limiting factor. Therefore, fertilization should be coordinated with other agricultural technical measures, and various fertilizers should be applied together. For example, water can control fertilizer, and the combination of fertilization and irrigation is very important.