Wednesday, November 4, 2009: 2:45 PM
Convention Center, Room 319, Third Floor
There are uncertainties about the sustainability of long-term monoculture and nitrogen (N) fertilizer use in corn production. Long-term research (50 years) at the Arlington Agricultural Research Station has examined the effects of continuous corn and N fertilizer use on corn yield, N use efficiency, and soil characteristics. Corn was harvested for grain with residues returned annually since 1958 on a Plano silt loam soil (fine-silty, mixed mesic, Typic Argiudolls). The experimental design includes three N fertilizer rates (currently, 0, 140 and 280 kg N ha-1) and two lime treatments (imposed in 1985) with four replications. Soil pH and organic matter content were measured periodically during the experiment. Average corn yields in N fertilized treatments increased dramatically (100%) over time with some of the highest yields occurring in the most recent years. Nitrogen use efficiency (grain N/fertilizer N) also increased over time, thus higher yields in recent years have not required greater N fertilizer use. Soil organic matter content was at least maintained and, in some cases, increased with long-term N additions, thereby enhancing the soil N supply capability. Soil pH decreased with long-term N use without lime addition, and since 1987, lime treatments increased yields in 13 of 21 years. Increasing productivity and N use efficiency along with no reduction in soil organic matter suggest that long-term continuous corn and N fertilizer use are sustainable practices in southern Wisconsin.