A. Summary of nitrogen, phosphorus and potassium fertilizers
Plants need a good ecological environment for normal growth, and nutrient conditions are one of the important factors. In order to obtain a good harvest of agricultural products, fertilization is an indispensable measure.
B. The basis for proper fertilization of plants
It must be based on the understanding of plant nutrient demand and fertilizer absorption pattern. As nitrogen, phosphorus and potassium fertilizers are commonly used in China today, it is relevant for us to master the role of nitrogen, phosphorus and potassium fertilizers for plants.
C. Plants in their life activities
Like all living things, crops need food to meet their growth, development and “reproduction” needs. However, the special function of crops is to absorb water and carbon dioxide from the air in order to obtain carbon, hydrogen and oxygen.
D. Production of organic bodies
They must also absorb nitrogen and other mineral nutrients from the soil and synthesize organic matter with the help of solar energy in order to build their own organic organisms.
Absorption of mineral nutrients from the soil in is the material basis of crop growth and development and the core of soil fertility, and is also one of the important signs to evaluate the high productivity of the soil.
2. Different varieties
Crop varieties are different and their development stages are different. The requirements for the type and quantity of soil mineral nutrients are different.
3. The two-sided role of plants
Some of these mineral nutrients are components of the crop, some can regulate the life activities of the crop. Some or both.
4. Important objections
Therefore, it is important for agricultural production to understand the need of crops for soil mineral nutrients and to grasp the existence status and change pattern of soil mineral nutrients.
E. The role of nitrogen fertilizer for plants
1. Sources of nitrogen
Until the 20th century, nitrogen in the soil came from the atmosphere during the natural nitrogen cycle.
2. The atmosphere contains 78% nitrogen
It enters the soil mainly through nitrogen fixation and atmospheric discharge, and is absorbed and used by plants. It may also further become food for animals.
3. Cycle of nitrogen
Animal manure and plant straw are the links in the atmosphere-soil-plant-animal nitrogen cycle.
4. Artificial production
Nowadays, a series of nitrogen-containing fertilizers such as urea and ammonium bicarbonate are manufactured through artificial synthesizers for nitrogen fixation. They are added to this cycle through soil application and foliar spraying.
5. Plant nitrogen
Animal manure and plant straw are organic materials that enter the soil. Under the action of a series of soil microorganisms, it undergoes a series of decomposition and transformation.
6. Carbon to nitrogen ratio less than 25
Ammonium nitrogen will released under the action of digestive bacteria, after two steps into nitrate nitrogen.
7. Conversion rate and quantity
Soil temperature, humidity, aeration condition, pH, microbial population size and other conditions determine the conversion rate and quantity. It takes a long period of time.
8. Carbon to nitrogen ratio greater than 30
Organic matter in the soil to absorb part of the original mineral nitrogen in the soil for microbial decomposition activities, and then release nitrogen after the carbon to nitrogen ratio is less than 25.
9. Organic fertilizer in plants
Organic fertilizer contains the highest nitrogen content of chicken manure, followed by pig manure, and the lowest nitrogen content of plant straw. Ammonium nitrogen in chemical fertilizer also has to converted into nitrate nitrogen, which is no different from organic fertilizer.
F. Nitrogen cycle in soil and atmosphere.
Ammonium is similar to potassium is easily adsorbed by the soil. Nitrate, on the other hand, is more easily lost with water and can cause environmental pollution by entering groundwater or rivers, lakes and seas. In poorly aerated, excessively moist soils nitrate will produce denitrification to generate nitrogen oxides released into the air for loss.
G. The role of nitrogen in crop nutrition
Nitrogen is an essential nutrient for plant growth, and it is a component of every living cell. Plants require large amounts of nitrogen.
Nitrogen is a component of chlorophyll, and both chlorophyll a and chlorophyll are nitrogen-containing compounds.
Green plants carry out photosynthesis, which converts light energy into chemical energy. The conversion of inorganic substances (carbon dioxide and water) into organic substances (glucose) is done with the help of chlorophyll.
(3) Organic plant materials
Glucose is the raw material for the synthesis of various organic substances in plants, while chlorophyll is the plant’s “food” factory. Nitrogen is also a component of the vitamin and energy system in the plant.
(4) Effects of nitrogen on plants
The effect of nitrogen on plant growth and development is very obvious. When nitrogen is sufficient, plants can synthesize more proteins. It promotes cell division and growth, so the plant leaf area grows faster. More leaf area can used for photosynthesis.
(5) Proper application of nitrogen fertilizer
Nitrogen fertilizer should applied with organic fertilizer, and nitrogen fertilizer should applied with phosphorus and potassium fertilizer. The application of different nitrogen fertilizer varieties, and the application of base fertilizer and follow-up fertilizer.
H. The role of phosphorus fertilizer for plants
1. Source plants of phosphorus
In fact, only the soil is the only natural source of nutrient elements for crop forests. The content and properties of phosphorus compounds responding to the soil are directly related to the crop growth and its effect on phosphorus fertilizer.
2. Content of total soil phosphorus
The general variation in 0.022%-0.109% (by P), the soil phosphorus content can range from 4-3000mg/kg. more than 99% of the total soil phosphorus is late-acting phosphorus. It cannot be absorbed by crops and is only an indicator of the potential fertility of soil phosphorus.
3. The role of phosphorus in plant nutrition
However, carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus are the elements that make up living organisms. Thus among them phosphorus is a vital element that makes up life activities, and no organism has been found that does not contain phosphorus in its life processes.
4.Important plant components
Phosphorus is an important component of compounds such as nucleic acid, phosphate, nucleoprotein, phosphoprotein, phospholipid and adenosine triphosphate, which are the living substances of biological cells. It accounts for about 0.2%-1.1% of the dry weight of crops. These compounds play an important role in the growth, development and quality of crops.
5. Important organic compounds
Such as nucleic acid, ribose and deoxyribonucleic acid in phosphorus content are generally above 10%.
6. Phosphorus to inorganic phosphate
Such as calcium phosphate, magnesium phosphate, potassium phosphate and other forms of storage, mostly concentrated in the seeds and fruits of crops. Beneficial to cell division, accelerating the growth of young shoots and root systems.
7. Organic phosphorus
However, organophosphorus is a component of important organic matter that enhances the production and operation of nitrogenous substances and carbohydrates in crops. Thus, it enhances the formation of starch, protein, oil and sugar and other vital activities.
8. The rational application of phosphorus fertilizer
First of all, the theoretical basis for the reasonable application of phosphorus fertilizer, mainly from the crop’s physiological properties of phosphorus absorption, the soil’s phosphorus supply properties, phosphorus fertilizer varieties and phosphorus fertilizer conversion mechanism in the soil and other aspects. Limit the base fertilizer relatively concentrated application, nitrogen and phosphorus with, drought heavy water light.
I. The role of potassium fertilizer for plants
①Source of potassium
Unlike nitrogen and phosphorus, all potassium in the soil exists in inorganic form in nature. And its quantity is much higher than that of nitrogen and phosphorus. However, its quantity is much higher than that of nitrogen and phosphorus, and the average potassium content of the earth’s crust is about 2.3%. Therefore the total potassium content of soils varies greatly and can be as little as traces or as high as 4% to 6%.
②Soil-forming parent material
Potassium in soils is largely influenced by the parent material and its degree of weathering, so its content varies greatly from parent material to parent material.
③ Under natural conditions
Thus parental potassium-bearing minerals are the main source of soil potassium. However, most of the soil potassium is present in potassium feldspar-bearing, mica ray primary minerals. A small amount is present in secondary potassium-bearing minerals such as illite and vermiculite. Therefore sandy soils and strongly weathered soils are low in potassium.
④ Role of potassium in crop nutrition
The amount of potassium absorbed by crops is generally similar to, and sometimes exceeds, the amount of nitrogen absorbed.
Potassium, unlike other nutrients, is not yet found as a compound in crops. It is almost in an ionic state, so it is most mobile in the crop and is mostly concentrated in the young tissues of the crop.
Potassium thus promotes all major physiological metabolic effects in the crop. It also plays an important role in increasing crop yield, improving product quality and increasing crop stress resistance.
⑦ Activation of enzymes by potassium
One of the most important physiological functions of potassium is the activation of an important enzyme system, the enzymatic reaction. More than 60 enzymes in crops have been identified as requiring potassium ions for activation, so potassium is involved in many metabolic processes in crops. Therefore, potassium is recognized as a “quality element”.
⑧The relationship between potassium fertilizer and the quality of fruits and vegetables
Therefore, increased application of potassium fertilizer can improve the quality and enhance the merchantability, storability, shelf life and resistance to pests and diseases of fruits. Potassium also enhances the resistance of fruits and vegetables to diseases and insects, thus improving the appearance, taste and merchantability of the products. 4.
⑨ Reasonable application of potassium fertilizer
The effect of potash application is therefore not only in the yield of the crop. It also significantly contributes to the improvement of the quality of agricultural products. Potassium is also beneficial to improve the quality of a variety of cash crop products, such as the yield of bananas and their composition can be significantly improved.
However, plant nutrition research can conducted to fully exploit the biological potential for efficient nutrient utilization. Thus optimizing fertilizer inputs, improving fertilizer utilization, reducing pollution and protecting the environment. The same can promote sustainable agricultural development.