Farming The main problem on modern intensive farms is the increased use of and dependence on chemical fertilisers, pesticides and insecticides. If applied in the wrong strengths, these can remain in the soil, and will also leach off the fields and into local water supplies. A frequently-ingredient in fertiliser is nitrogen which, if left in a heavy concentration in the soil can actually alter the acidity, or pH, and so change the variety of plants able to grow in that environment. Both agricultural crops and the natural vegetation can be affected by polluted soil. Some of the poisons are taken up by the plants and animals we eat and so enter our bodies. This can lead to cancers and a wide variety of other illnesses. Responsible farmers are able to regulate the amounts of fertilisers and pesticides being applied so as not to cause these problems.