Wednesday, November 7, 2007
296-21

P, K, and Micronutrient Stratification in Long-Term No-Till in Virginia's Coastal Plain.

Catherine Byers, Department of Crop Sciences, University of Illinois at Urbana Champaign, 1102 S Goodwin ave., N-207 Turner Hall, Urbana, IL 61801, John Spargo, Smyth Hall, Virginia Tech, Virginia Tech University, Crop & Soil Environmental Sciences- 0404, Blacksburg, VA 24061, and Marcus Alley, 416 Smyth Hall, Virginia Tech, Virginia Tech, Crop & Soil Environmental Science, Blacksburg, VA 24061-0403.

An issue that arises with continuous no-till management is the stratification of nutrients that may result from the lack of incorporation.  This has a number of possible implications. For example, nutrient availability may be enhanced due to the increased solubility of unincorporated nutrients.  Nutrient availability may also be inhibited due to lack of incorporation. Water quality may also be affected if the accumulation of eutrophying nutrients, like P, at the surface makes them susceptible to runoff losses. We investigated pH, bulk density, and Mehlich 1 extractable P, K, Ca, Mg, and stratification in three different soil series in the Coastal Plain of Virginia.  Sixty five fields were sampled with a history of continuous no-till management ranging from 0 to 14 years. Approximately half of the locations also have a history of biosolids application.  Vertical distribution of the soil properties were measured at: 0-2.5, 2.5-7.5, and 7.5-15 cm depths.  Stratification ratios were determined between the 0-2.5 cm layer and the 7.5 -15 cm layer. Stratification of Ca and Mg increased with duration of no-till management. The concentrations of Ca and Mg were consistently higher in the surface 0-2.5 centimeters at sites that had received biosolids applications.  Bulk density decreased in the 0-2.5 cm layer with duration of continuous no-till due to the increase of organic matter at the soil surface.  At most sites, P was more highly stratified with the addition of biosolids and the duration of no-till.