Tuesday, November 3, 2009
Convention Center, Exhibit Hall BC, Second Floor
Due to conservation awareness, improved technology, and increased fuel costs, no-till management has been implemented on a significant portion of U.S. cropland. Continuous no-till management can have a significant influence on soil N cycling and fertilizer N use efficiency. It has also been suggested that NO3-N leaching losses may be increased with no-till cultivation since infiltration rates are generally increased. Little research has been conducted to investigate NO3-N leaching from soils managed using continuous no-till in the Mid-Atlantic Coastal Plain and studies conducted in other regions have produced conflicting results. In order to compare NO3-N leaching losses between tillage systems, four long-term no-till sites paired with four rotational tillage sites across four soil series were selected. The soils selected for study represent the majority of land area used for agronomic crop production in the region. Cropping sequence at all locations was a corn (Zea mays) – wheat (Triticum aestivum) or barley (Hordeum vulgare) – double crop soybean (Glycine max) rotation. Three passive capillary wick samplers were installed 100 cm below the soil surface at each site. Leachate samples were collected from September 2005 through September 2009, analyzed for NO3-N and reported on a concentration and mass basis. There were no consistent effects of tillage management on the concentration or mass loss of NO3-N leached. There was a rotational effect, with most of the NO3-N losses occurring during periods of low evapotranspiration (i.e., fallow period following soybean harvest). This illustrates the value of cover crops during fallow periods to minimize NO3-N leaching losses.