CHEMICAL VERSUS ORGANIC FARMING Chemical pesticides and artificial fertilisers ________________(spread) use in farming since the middle of the 20th century. When they were first introduced, many farmers welcomed them ____________a great way to fight crop disease and increase production. Over time, however, ______________ some scientists have found is that their long-term use can sometimes harm _______________ the land and people’s health. For example, pesticides can damage the land ___________killing not only harmful bacteria and insects, ____________ also helpful ones. In addition,