How to decide which fertilizer to apply

Plants need to absorb various nutrients for their growth and development. However, the nutrient factors that determine the crop yield are the relative minimum content in the soil, and the output also changes within a certain limit with the increase or decrease of this factor. Water barrels are usually used for explanation.
Barrels consist of wooden planks representing different nutrient contents and factors, and the amount of water stored is determined by the height of the shortest plank. If the minimum nutrients are not purposely supplemented, it will be difficult to increase the yield even if other nutrients are increased. This will only lead to a waste of fertilizer. The minimum nutrient is also not fixed. When the minimum nutrients in the soil are replenished and the crop meets the demand, the yield will increase rapidly. The original minimum nutrient will no longer be the minimum nutrient but will be located in other nutrients.
For example, at the beginning, nitrogen is the most scarce, the smallest nutrient, and the yield level is limited by nitrogen. After nitrogen is added, phosphorus becomes the minimum nutrient and the yield level is limited by phosphorus. After both nitrogen and phosphorus are increased, potassium becomes the minimum nutrient, and the yield level is limited by potassium. The use of nitrogen and phosphorus fertilizers in soils with severe potassium deficiency will not increase crop yields.
Of course, many factors affecting crop yield are intertwined. Factors and factors promote each other and restrict each other, and they are constantly changing. For example, the deficiency of phosphorus affects the fertilizer effect of nitrogen; the increase of potassium fertilizer can increase the absorption of nitrogen; excessive application of phosphate fertilizer leads to the precipitation of zinc and is prone to zinc deficiency. Crop yield is the result of a combination of factors that affect crop growth and development. In order to give full play to the role of fertilizer production and improve the economic efficiency of fertilizer, on the one hand, we must pay attention to the coordination and application of various nutrients. On the other hand, the fertilizer application measures should also be closely coordinated with other agricultural technical measures to give full play to the comprehensive role of the factors.