Wednesday, November 7, 2007
327-3
Long Term Impact of Aluminum Water Treatment Residuals Applied to P Impacted Soils on Plants Phosphorus and Trace Elements.
Lee Jacobs and Olawale Oladeji. Michigan State University, Dept. of Crop & Soil Sciences, East Lansing, MI 48824-1325
High soil P test levels can be of environmental rather than agronomic concern in areas of intensive crop and livestock production. To determine if excess soil soluble P could be safely reduced by applying Al rich water treatment residuals (Al-WTR), long term agronomic impacts of land applied Al-WTR was evaluated at six sites having soils with very high soil test P (STP) levels. Two sites were established each year for amendment with three rates of Al-WTR in 1998 (0, 38, and 114 dry Mg ha-1), 1999 (0, 45, and 134 dry Mg ha-1), and 2000 (0, 74, and 222 Mg ha-1) in RCB design with four replicates per treatment. Corn (Zea mays L.) was planted at most sites for five growing seasons, except in 2000 and 2001 when soybeans (Glycine max L.) were planted at sites 4 and 6, to monitor yields and plant composition. The applied WTR reduced water soluble P in soil (measured as CaCl2 –extractable P) and Bray P1 but neither grain yields nor P concentrations in plant tissue samples were reduced at any of the six sites. The Al-WTR amendments did not increase A1 or decrease Ca and Mg concentrations in plant tissue grown in WTR-amended soils compared to untreated soils at any of the sites. No reduction in B, Cu, Fe, Mn, Mo, and Zn concentrations in plant tissue samples were observed in either crop grown at any of the six sites. This study shows that applying Al-WTR to soil having high STP levels will reduce water soluble P in the amended soil without any negative agronomic impact.