Organophosphorus pesticides cannot function as foliar fertilizers

Some people have analyzed that the active ingredients of organophosphorus pesticides contain phosphorus, which is an essential nutrient for plants. Therefore, the use of organic phosphorus promotes the growth of plants. On the other hand, it has been observed that some crops become greener after spraying organophosphorus pesticides, and some people use organophosphorus pesticides as leaf surface to apply phosphate fertilizer. In fact, this is a wrong view.

First, we say that the function or trait of any object is determined by its internal structure. For example, charcoal, graphite and quartz are composed of carbon elements, but the crystallization is different, and the hardness is very different. Both organophosphorus pesticides and phosphate fertilizers do contain phosphorus, but the way in which phosphorus is combined with other elements (chemical structural formula) is different. Phosphate fertilizer is some phosphate, which is easily soluble in water and is in the state of phosphate (PO4-3) ion in water. It can be quickly absorbed and utilized by plants; while the phosphorus in organic phosphorus is mostly incorporated into large organic molecules. Some phosphates or phosphorothioates are generally insoluble in water and do not ionize phosphate. Although some agents can penetrate into plants and even be absorbed by plants, they cannot directly participate in normal metabolic processes.

Secondly, we say that organophosphorus pesticides may become bio-degradable phosphates in nature or in plants, but generally require long periods of time and appropriate environmental conditions. We know that any pesticide has a "validity period" and a "safe interval." The former refers to the number of days that an agent can effectively kill pests, and can often be maintained for several days to one week. The latter is the last application of the number of days from the harvest or the loss of toxicity of the agent, often several dozen days, and the agent can be degraded to Plants take much longer than these.

On the other hand, we should also pay attention to the fact that the amount of organophosphorus pesticides per acre is small, the phosphorus content of the active ingredients is also very small, and the phosphorus that can be brought into the farmland by spraying organic phosphorus is quite limited. Taking dichlorvos as an example, the amount of phosphorus carried by spraying once is about one-twentieth of that of potassium dihydrogen phosphate.

In short, don't expect to rely on the use of organophosphorus pesticides to supplement the phosphorus needed for crops, and can't expect it to play the role of foliar topdressing.

(Xiao Yueyan)