Current assessments of benefits of summer fallow on clean fields suggest that in many cases it leads to erosion and nutrient leaching, unless a cover crop is employed. While chemical fertiliser can replace nutrient losses the presence of organic matter provides better physical characteristics and as well as micro-nutrients that can affect plant growth. While no-till and conservation till systems require the purchase of synthetic herbicides to be effective the initial cost of herbicides is offset by higher yields and improved soil quality.