Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2008
Publication Date: 9/1/2008
Citation: Winzeler, H.E., Owens, P.R., Joern, B.C., Camberato, J.J., Lee, B.D., Anderson, D.E., Smith, D.R. 2008. Potassium fertility and terrain attributes in a Fragiudalf drainage Catena. Soil Science Society of America Journal. 72:1311-1320.
Interpretive Summary: Site-specific management of soil fertility has been based on soil sampling, with little attention paid to terrain features. This study was conducted to assess the influence of soil potasium (K) fertility with resepct to landscape position in southeastern Indiana. The landscape position and the soil drainage were directly correlated to the amount of exchangeable K and plant available K in the soil. Terrain attributes can aid in soil K fertility evaluations, because they relate well statistically to soil K fertility measurements. The impact of this research is to inform researchers and practicioners about the importance of using landscape features as one input for precision nutrient management.
Technical Abstract: Site-specific management of soil fertility has been based on soil sampling in grid patterns or within soil mapping units without taking full advantage of terrain/soil relationships, often thought to pertain to pedology as a separate discipline. The topographic wetness index (TWI), a terrain attribute that comprises the upstream contributing area and the slope for a portion of land, relates to soil wetness. The goal of this study was to determine whether terrain attributes relate significantly to soil K availability. We measured exchangeable K, nonexchangeable K, and terrain attributes in a 3.6 ha farmed site in the Cincinnati Catena, a major toposequence in the Muscatatuck Uplands Region of Indiana. Plant-available-nonexchangeable potassium (PANK) and exchangeable K were significantly (p < 0.0001 and p < 0.05) related to TWI and relative elevation in models that included anisotropic spatial autocorrelation variance estimates in three dimensions (latitude, longitude, and soil depth). The K availability increased with decreasing values of the TWI and in the drainage class order: poorly < somewhat-poorly < moderately-well-drained. Exchangeable K decreased with soil depth, while PANK increased. The PANK/K ratio was significantly higher in the poorly drained soils than in the moderately well-drained soils, implying greater mobility or weathering of K in wetter soils. Effective cation exchange capacity also showed strong relationships to terrain attributes. Possible mechanisms for these relationships include lateral downslope lessivage and K leaching. Terrain attributes can aid in soil K fertility evaluations on the Cincinnati Catena because they relate well statistically to soil K fertility measurements.