Who can talk about the types of common fertilizers and the effects of various fertilizers on plants?

First, the requirements of teaching purposes

1. Understand the importance of chemical elements to plant growth and the types and functions of commonly used fertilizers.

2. Understand the environmental impact of chemical fertilizers and pesticides.

3. Cultivate the ability to use the knowledge and skills learned to solve practical problems.

Second, the analysis of this topic

This topic is divided into two parts. One is the introduction of chemical fertilizer, which briefly introduces the types and functions of chemical fertilizer. The second is the simple identification of chemical fertilizers, and the identification methods of several common chemical fertilizers are introduced.

There are many kinds of fertilizers, and the knowledge involved is also very complicated. This topic briefly introduces the function and influence of chemical fertilizer. This part can be divided into two aspects: on the one hand, it talks about the benefits of using chemical fertilizers, and briefly explains the role of chemical fertilizers in increasing agricultural production in the introduction part of the subject. Taking commonly used nitrogen, phosphorus and potassium fertilizers as examples, the important roles of nitrogen, phosphorus and potassium in plant growth are further introduced, which provides theoretical and factual basis for the role of chemical fertilizers in increasing agricultural production and shows the value of chemistry. On the other hand, it talks about the environmental pollution caused by the use of chemical fertilizers, and at the same time, it briefly mentions the use of pesticides, another important chemical product in agricultural production, from the environmental point of view. Thus, the problems faced by human beings in the use of chemical fertilizers and pesticides are presented to students comprehensively and truly, so that they can understand both the problems that have been solved in scientific development and the problems that remain to be solved in scientific development.

As for the simple identification of chemical fertilizers, the textbook explores and introduces the differences among nitrogen, phosphorus and potassium fertilizers and the identification of different nitrogen fertilizers in the form of activities, explorations and materials. The former uses the differences of physical and chemical properties of nitrogen, phosphorus and potassium fertilizer to design simple experiments to guide students to observe, analyze and compare their differences and summarize the methods of distinction. Students can not only understand the simple identification methods of three fertilizers, but also learn and experience how to apply what they have learned to solve practical problems. For rural students, it has certain practical value. The simple identification of nitrogen fertilizer provided in the data is actually a simple chemical analysis, which involves the chemical properties of ammonium salts that some students have not learned (explained in the form of small notes), and does not affect the actual operation. Students interested in this aspect can read and use it.

The teaching suggestions are as follows:

1. The knowledge of chemical fertilizers in textbooks is very limited. The key point is to let students understand some trends of chemical fertilizer and agricultural development and establish some concepts. In teaching, teachers can appropriately supplement some related materials, such as the general situation and trend of chemical fertilizer development; It can also be combined with the investigation and research after this topic to mobilize students to collect information and enrich the teaching content.

2. Combined with the study of biology class, we can carry out extracurricular experimental activities on the influence of chemical fertilizer on plant growth.

3. Schools located in rural areas or near rural areas should combine the actual situation of local agricultural production, supplement the application knowledge and technology of some specific types of fertilizers and pesticides, and combine learning with application.

Pay attention to the advantages and disadvantages of using chemical fertilizers and pesticides, cultivate and train students' dialectical thinking, and make them realize that the development of science and technology may often produce new problems while solving the original problems and promoting the development of society and production, so as to realize that the progress of science and technology will be endless.

Third, information.

1. Plant nutrient elements

Nutrient elements required for normal growth and development of plants are divided into essential elements and beneficial elements. Among the essential elements, there are many elements (also called constants) and trace elements.

Essential elements refer to plant nutrient elements that are necessary for the normal growth and development of plants and cannot be replaced by other elements. According to the needs of plants, essential elements are divided into essential macro elements and essential trace elements. The essential macroelements are carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, potassium, magnesium and calcium; The essential trace elements are iron, manganese, zinc, copper, boron, molybdenum and chlorine. Although the requirements of macroelements and microelements are different, they all have important functions and are indispensable for plant life activities.

The physiological functions of essential elements can be summarized as: forming organic structures in plants, participating in enzymatic reactions or energy metabolism and physiological regulation. Such as cellulose, monosaccharide and polysaccharide containing carbon, hydrogen and oxygen; Protein contains carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur; Some enzymes contain iron or zinc; Mg2+ and K+ are activators of two different enzymes. K+ and Cl- play an important role in osmotic adjustment.

Beneficial elements refers to the elements necessary for the normal growth and development of some plants, but not all plants. Such as silicon, cobalt, nickel, sodium, etc.

Silicon is necessary for Gramineae plants such as rice, wheat and sugarcane, and also has certain effects on tomatoes, cucumbers, kidney beans and strawberries. Lack of silicon will weaken the fertilization ability of plants in reproductive growth period and reduce the quantity and weight of fruits.

Cobalt is necessary for nitrogen fixation and nodule growth of leguminous plants; Nickel plays an important role in nitrogen metabolism of leguminous plants.

Some beneficial elements can not only promote the growth and development of some plants, but also replace some physiological functions of an essential element. For example, for some sodium-loving plants (sugar beet, etc. ), Na+ can replace K+ in osmotic adjustment. When K+ is in short supply, Na+ can replace K+.

2. Classification and development trend of fertilizers

Substances that can directly or indirectly provide nutrients for crops are called fertilizers. There are many kinds of fertilizers, with different sources, components, properties, fertilizer efficiency and application methods. According to the function of fertilizer, fertilizer can be divided into direct fertilizer and indirect fertilizer. Direct fertilizer mainly provides necessary nutrients for crops and has direct nutritional effect on crops. The main function of indirect fertilizer is to adjust soil pH value, improve soil structure, improve soil physical and chemical properties and biochemical properties, and coordinate crop growth and development.

The development trend of fertilizer is consistent with the development of agriculture and the whole society. On the one hand, in order to improve the utilization rate of fertilizer, save energy, reduce costs, facilitate storage, transportation and application, and not pollute the environment, the production of fertilizer is developing towards high efficiency (that is, the concentration of effective nutrients contained in fertilizer is high) and mixed (containing various nutrients, including pesticides, hormones, herbicides, etc.). ), long-acting (long duration of fertilizer effect) and liquefaction. On the other hand, in order to maintain soil fertility, reduce agricultural costs, reduce environmental pollution, maintain the normal circulation of nutrients in the food chain, and maintain the agricultural ecological balance, it is also an important trend of fertilizer development in agricultural production to establish and popularize the fertilization system of combined application of organic fertilizer and chemical fertilizer in fertilizer application and crop cultivation system, crop and pasture rotation cultivation, straw returning to the field, and application of green fertilizer (fertilizer made by direct burial or composting of green plants).

3. Comparison between chemical fertilizer and agricultural fertilizer

According to the source of fertilizer, fertilizer can be divided into farmyard manure and chemical fertilizer.

Farmhouse manure is mostly organic fertilizer. There are many kinds of farm manure (such as human manure, livestock manure and manure, green manure, compost and compost, etc.). ), and the source is wide, the quantity is large, the local materials are convenient, and the cost is relatively low. Organic fertilizer is characterized by comprehensive nutrients, including not only nitrogen, phosphorus and potassium, but also calcium, magnesium, sulfur, iron and some trace elements. Most of these nutrients are in organic state, which is difficult to be directly absorbed and utilized by crops. They must be gradually released through chemical and physical actions in the soil and the fermentation and decomposition of microorganisms, so the fertilizer efficiency is long-term and stable. In addition, the application of organic fertilizer is beneficial to promote the formation of soil aggregate structure, coordinate the proportion of air and water in soil, loosen soil, and increase the ability of water retention, heat preservation, ventilation and fertilizer conservation.

Although farmyard manure contains a variety of nutrients, its content is relatively small and its fertilizer efficiency is slow, which is not conducive to the direct absorption of crops. These weaknesses of farmyard manure are precisely the advantages of chemical fertilizer. The content of nutrient elements in chemical fertilizer is high, for example, the nitrogen content in 1 kg ammonium bicarbonate is equivalent to 25 kg~30 kg human feces; The phosphorus content of 1 kg superphosphate is equivalent to 60 kg~80 kg manure; 1 kg potassium sulfate is equivalent to 10 kg in plant ash. Most chemical fertilizers are easily soluble in water, which can be quickly absorbed by crops after being applied to soil, and the fertilizer efficiency is rapid and remarkable. If ammonia water is used as topdressing, the yellow, thin and short seedlings can turn green in a short time. In addition, raw materials for the production of chemical fertilizers are abundant. For example, the air and water needed for the production of nitrogen fertilizer are inexhaustible, and other raw materials such as coal and oil are also stored in large quantities in China. Therefore, chemical fertilizers can be produced in large quantities and widely applied.

Compared with farmyard manure, chemical fertilizer contains a single nutrient, which can not meet all kinds of nutrients needed for plant growth, and its cost is also high. Therefore, generally speaking, when applying fertilizer, it is always on the basis of increasing the application of farmyard manure and cooperating with the use of chemical fertilizers, which can help and supplement each other.