From the Chatham Daily News we found this story which provides a basic explanation of precision farming:

GPS is part of precision agriculture, which is doing the right thing at the right place at the right time. More precise application of pesticides, herbicides, and fertilizers, and better control of the dispersion of these agri-products, is possible through precision agriculture. This reduces the farmer’s expenses, produces a higher yield, and creates more environmentally-friendly farming operations.