Title: Response surface models of subsoil K concentration for loess over till soils in Missouri Authors
Submitted to: Soil Fertility Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: November 1, 2012
Publication Date: November 14, 2012
Citation: Myers, D.B., Kitchen, N.R., Miles, R.J., Sudduth, K.A., Sadler, E.J., Grunwald, S. 2012. Response surface models of subsoil K concentration for loess over till soils in Missouri. 42nd North Central Extension-Industry Soil Fertility Conference Proceedings. CDROM. Technical Abstract: Crop uptake of potassium (K) has demonstrated sensitivity to subsoil variation in K content. This fact has not been sufficiently considered in K management strategies in part due to logistical difficulties in sampling spatially variable subsoil K. We propose a simplified soil factorial model, a response surface, to enable site-specific accounting of whole root zone K supply for loess over till soils. We compared the performance of two peak functions and a non-parametric local regression procedure to model soil-landscape K variation. These models were trained and tested on soil profile K sampled from within Missouri’s Major Land Resource Area 113, the Central Claypan Areas. The local regression procedure was found to be most appropriate for mapping subsoil K because it is simple, quick, and readily provides prediction intervals. These results highlight the potential we have to account for and manage whole root zone K site-specifically.