Soil testing and fertilization require mastery of three principles and six principles

Introduction: Soil testing and fertilization are based on soil testing and fertilizer field experiments. Based on crop fertilizer requirements, soil fertilizer supply capacity, and fertilizer effects, reasonable application quantities, scientific application periods, and methods of fertilizers such as nitrogen, phosphorus, potassium, and trace elements are proposed on the basis of rational use of organic fertilizers. The core is to regulate the contradiction between crop fertilizer requirements and soil fertilizer supply. Simply put, it is to measure soil nutrients and "open" according to the nutrients needed for crop growth, supplementing what is lacking and what is lacking. The fertilizer applied can meet the needs of crop growth without causing waste, achieving the goal of combining land use and land cultivation, and balancing input and output.

There are three main principles to master when conducting soil testing and fertilization:

(1) Combining organic and inorganic elements. Emphasizing the use of organic fertilizers as the foundation, the application of organic fertilizers is an effective way to improve the quality of agricultural products, enhance soil fertility, maintain soil fertility, and improve agricultural and ecological benefits. The combination of organic and inorganic can play a role in balancing urgency, complementing each other, and improving fertilizer efficiency.

(2) Combining large, medium, and trace elements. Elements with relatively low content in soil are limiting factors for crops to absorb other nutrients, which in turn affect yield and quality. The combination of nitrogen, phosphorus, and potassium, as well as the supplementation of necessary medium and trace elements, is the main means to achieve high yields.

(3) Combining land use with land conservation, achieving a balance between input and output. To achieve a virtuous cycle of substances and energy formed by crops, soil, and fertilizers, it is necessary to adhere to the combination of use and nutrition. Reasonable crop rotation, application of organic fertilizers, micro fertilizers, etc., can provide scientific rest and recuperation for cultivated land, which is a long-term strategy for sustainable agricultural development.

1、 Main principles of soil testing and fertilization

1. Nutrient return theory: Crop growth requires the absorption of mineral nutrients such as nitrogen, phosphorus, and potassium from the soil. As humans plant crops on the land and take away their products, the nutrients in the soil will become increasingly scarce, inevitably leading to a gradual decline in soil fertility. Therefore, in order to restore soil fertility and increase yields, it is necessary to return everything taken from the soil, which is the "nutrient return theory".

2. The law of small nutrients: Plants need to absorb various nutrients in order to grow and develop. But it is the nutrient factors with relatively low content in the soil that determine crop yield, and the yield also changes relatively within a certain limit with the increase or decrease of this factor, which is the "law of small nutrients".

3. The law of diminishing returns: In the case of soil nutrient deficiency, fertilization according to the needs of crops will result in a corresponding increase in crop yield. But the increase in fertilizer application is not positively correlated with the increase in yield. When the amount of fertilizer applied is very low, the yield increase per unit of fertilizer is significant. As the amount of fertilizer applied increases, the yield increase per unit of fertilizer shows a decreasing trend. When the amount of fertilizer applied reaches a certain level, no matter how much fertilizer is applied, the yield will not increase. This is the "law of diminishing returns".

4. The principle of equal importance: There are over 20 known nutrients required for crop growth, among which carbon, hydrogen, and oxygen can be obtained from air and water and generally do not need to be provided in the form of fertilizers. Nitrogen, phosphorus, and potassium have a high content in crops and are absorbed more, known as "macroelements" or "fertilizer elements". Calcium, magnesium, and sulfur are generally referred to as "moderate elements". Copper, zinc, iron, manganese, boron, molybdenum and other elements are called "trace elements" as crops require less. For crops, both large, medium, and trace elements are equally important and indispensable. This is the law of equal importance.

5. Irreplaceability law: Various nutrients required by crops have certain functions within the crop and cannot be replaced by each other. If a nutrient element is lacking, it is necessary to apply fertilizers containing that nutrient element. Applying other fertilizers not only cannot solve the problem of nutrient deficiency, but sometimes can also worsen the symptoms of nutrient deficiency. This is the 'irreplaceable law'.

6. The law of comprehensive action of factors: The high or low yield of crops is the result of the comprehensive action of many factors that affect crop growth and development. Such as nutrients, climate, water, soil, production management technology, etc.