Breaking Plowpans Using Low Energy Tillage

SOME methods of reducing energy required to break plowpans were evaluated during the last two years. This work was initiated in an effort to reduce the energy required to break plowplans as commonly practiced in under-row subsoiling. Trials were initially conducted at The University of Georgia Southeast Branch Experiment Station located at Midville, Georgia. Under-row subsoiling or chiseling is widely used in the coastal plains in the Southeastern United States with major row crops such as tobacco, soybeans, corn, cotton and grain sorghum. The authors estimate this practice to be used on at least 75% of the acreage of the above crops in the coastal plains of Georgia. In conjunction with the under-row subsoiling, it is common practice to make beds immediately over the slot made by the subsoiler in a once-over tillage operation. After the plowpans are broken and the beds are formed, the soil is normally left undisturbed for several weeks, hopefully with at least one rain before the beds are knocked down exposing a level, moist soil for planting. This provides a mellow, moist seedbed almost ideally suited for row crops. The power requirement to pull the under-row subsoiler-bedder is fairly high, often requiring dual wheels with hydro ballast or even four wheel drive tractors in some instances. Most conditions require about 22.5 kW (30 hp) per row at field speeds of 6.4 km/h (4 mph). Traction is a major problem in sandy soils where the plowpans must be penetrated and broken below the sandy layer 20.3 to 30.5 cm (8 to 12 in.) below the soil surface. If the plowpan is not broken, the plant and root development is often hampered with yield reduction common. Thus the practice of subsoiling under the row is widely accepted in the coastal plains of Georgia and increasingly in the Southeast.