This kind of intensive agriculture comes with its own set of problems. Farmers use a lot of chemical fertilizers, pesticides (chemicals that kill bugs), and herbicides (chemicals that kill weeds). These chemicals can pollute the soil or the water. They can also create bugs and weeds that are more resistant to the chemicals, causing outbreaks of these pests. The soil can be damaged by erosion (blowing or washing away), salt buildup, or loss of structure. Irrigation (adding water from rivers) can pollute water and lower the water table. These problems have all got solutions, and modern young farmers usually have a good technical education.