Pesticides and fertilizers: friends or enemies?

Plant pests and soil fertility are two external factors that affect crop yield. The use of pesticides effectively prevented, destroyed and controlled "pests"; the use of chemical fertilizers, especially nitrogen fertilizers, improved soil fertility, which was one of the main reasons for the surge in food production in Asia during the Green Revolution.

In 2010, worldwide sales of pesticides are expected to exceed US $40 billion, with herbicides accounting for the largest market share. In addition, world mineral fertilizer production increased by nearly 350 per cent between 1961 and 2002. In the past 40 years, the use of inorganic fertilizers has brought about a record increase in grain production by about 40%.

The enemy

In 2011, toxic red tides caused by fertilizer losses covered 1/3 of Lake Erie in North America.

Due to the excessive use of pesticides and fertilizers, we are faced with a series of the most serious environmental pollution problems, including soil and water acidification, pollution of surface and groundwater resources, and increasing greenhouse gas emissions. Usually, less than 1% of pesticides actually enter the target pests, while the rest cause air, soil and water pollution. At present, in China, the nitrogen absorption efficiency of rice, wheat and corn is only about 26% to 28%, while the absorption rate of vegetable crops is less than 20%, and the rest is completely lost to the environment.

Over-reliance on pesticides not only damages the balance of the ecosystem, but also aggravates the vicious circle of drug resistance of pests. This has led to a further increase in investment in the development and utilization of pesticides, but the crop losses caused by insect pests have hardly changed, and are now basically the same as they were 50 years ago, estimated at about 30% to 40%. The result is an increase in the number of pest outbreaks due to improper use of pesticides.

In addition, the problem of pesticide residues in food is also worrying.

The way forward

On a farm in Pennsylvania, chicken droppings are used as fertilizer. Moving cages carry chickens to every corner of the farm to prevent manure from seeping into nearby Chesapeake Bay.

At present, the challenge is to abandon the existing unsustainable mode of production and shift to land-based production, and to use ecosystem methods to solve pest problems and provide a solid foundation for sustainable intensification of crop production. This is the direction of FAO's efforts.