ABSTRACT
No-till (NT) farming began evolving in the United States during the Dust Bowl days of the 1930s. As a means of controlling wind erosion, stubble-mulching became a common practice. Stubble-mulching involved pulling V-shaped blades about 10 cm beneath the soil surface to cut the roots of weeds and leaving most of the crop residues on the soil surface. As herbicides became common, there was a movement to even less tillage and, in some instances, NT. Water erosion was also significantly reduced by tillage systems that left more crop residues on the soil surface. Clean tillage, either by moldboard plowing or intensive disc tillage, was the standard in the United States for many years. Today, clean tillage is discouraged and is in the minority. The Conservation Technology Information Center (2002) reported that clean tillage was practiced on 42.7% of the cropland in the United States compared to 57.3% in some form of reduced tillage including 17.6% NT.
