HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Winzeler, H. E. Articles by Smith, D. R. Search for Related Content PubMed Articles by Winzeler, H. E. Articles by Smith, D. R. Agricola Articles by Winzeler, H. E. Articles by Smith, D. R. Related Collections Pedology Soil Fertility and Productivity

SOIL FERTILITY & PLANT NUTRITION

Potassium Fertility and Terrain Attributes in a Fragiudalf Drainage Catena

^a Dep. of Agronomy, Purdue Univ., West Lafayette, IN 47907
^b Dep. of Statistics, Purdue Univ., West Lafayette, IN 47907
^c National Soil Erosion Research Lab., West Lafayette, IN 47907

^* Corresponding author(prowens{at}purdue.edu).

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. The goal of this study was to determine whether terrain attributes relate significantly to soil K availability. 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. We evaluated Mehlich-3 K (M3K), plant-available nonexchangeable K (PANK) with a modified tetraphenylboron extraction, effective cation exchange capacity (ECEC), and other soil variables from soil samples taken at three depths, and terrain attributes in a 3.6-ha farmed site in the Cincinnati catena, a major toposequence in the Muscatatuck Uplands region of Indiana. The PANK and M3K were significantly (P < 0.0001 and P < 0.05, respectively) related to TWI and relative elevation in models with anisotropic spatial autocorrelation variance estimates in three dimensions (latitude, longitude, and soil depth). The PANK and M3K increased with decreasing TWI in the following drainage class order: poorly < somewhat poorly < moderately well drained. The M3K decreased with soil depth, while PANK increased. The PANK/M3K 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. The ECEC also related strongly to terrain attributes (P < 0.0001 for relative elevation, TWI, and interaction effects). Possible mechanisms include lateral downslope lessivage and K leaching. Terrain attributes can aid in soil K fertility evaluations on the Cincinnati catena because they relate well to soil K fertility measurements.

Abbreviations: DEM, digital elevation model • ECEC, effective cation exchange capacity • M3K, potassium extracted with Mehlich-3 extractant • PANK, plant-available nonexchangeable potassium • TPB, tetraphenylboron • TWI, topographic wetness index