Submitted to: Soil Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 26, 1997
Publication Date: N/A
Interpretive Summary: Erosion can be excessive when corn and soybean are grown using conventional tillage under the soil and climatic conditions characteristic the northeastern United States. Although the risk of soil loss can be reduced by plowing and planting on the contour, erosion can still exceed the tolerance in some years. Conservation tillage can greatly reduce the risk of soil loss, but concentrations of surface-applied herbicides and nitrat in runoff can exceed drinking water standards, especially in the first few runoff events after application. We evaluated a reduced-input management practice for corn and soybean production in which light disking and cultivation were used for weed control and manure and a legume supplied some of the nitrogen needed for crop production. Our objective was to determine if a balance between losses of soil and purchased chemical inputs could be obtained. Soil losses were similar to those under conservation tillage, but the risk of yield loss increased with reduced-input managemen due to inability to cultivate in a timely manner due to weather conditions. Farmers will benefit from the knowledge that herbicide use can be reduced, if so desired, without greatly increasing the risk of soil loss if tillage operations are kept to a minimum.
The NAEW near Coshocton, Ohio was established to develop, evaluate, and refine conservation practices that reduce runoff and erosion under the hilly, humid, conditions of the northeastern USA. Small (0.5 to 1 ha), single-practice, gaged watersheds comprised of sandstone- and shale-derived residual soils are used to evaluate the interaction of management, climate, ,and soils. In a 28-yr, 9-watershed, study 92% of the erosion occurred during the corn years of a 4-yr corn/wheat/meadow/meadow rotation. These watersheds were plowed prior to planting corn and cultivation was used for weed control. By tilling and planting on the contour and increasing fertility levels, soil loss was reduced more than 3-fold, but still averaged 4.7 Mg/ha during corn years. Thus, annual production of row crops on a sustainable basis was not without risk. A 6-yr, 6-watershed, study indicated that by using reduced tillage and herbicides, corn and soybean can be grown in rotation with an average soil loss of 0.5 Mg/ha/yr, well below the stipulated soil loss tolerance, if a rye cover crop followed soybean. Under these conditions, however, concentrations of surface applied herbicides and nitrate in runoff frequently exceeded drinking water standards, particularly in the first few runoff events after application, and may be a concern. A reduced-input management practice for corn and soybean production with light disking and cultivation for weed control and manure and a legume to supply some of the nitrogen was implemented to determine if a balance between losses of soil and purchased chemical inputs could be obtained. In a 6-yr comparison, soil losses were similar to those under conservation tillage, but the risk of yield loss increased due to inability to cultivate in a timely manner due to weather conditions.