Submitted to: Bouyoucos Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/10/1999
Publication Date: N/A
Interpretive Summary: Many problems associated with the development and adoption of conservation tillage systems cannot readily be discovered and corrected without a detailed evaluation in long-term field trials designed to test alternative systems side-by-side. Discovery and correction of a problem can provide a generic solution for a producing region, such as poorly drained soils in the northern Corn Belt. Reduced tillage depth and uncontrolled traffic associated with reduced tillage systems were identified to cause poor internal drainage; a strip-till or ridge-till system was recommended to correct deficiencies in the conservation tillage systems being adopted. This information can now be used by Extension; customers, and stakeholders to improve tillage systems and internal soil drainage on fine textured soils in the northern Corn Belt.
Technical Abstract: Tillage and tracking have profound effects on the geometry of soil structure, which directly influences soil hydraulic properties and internal soil drainage. Where internal soil drainage is already limiting, tillage and tracking can be limiting. Penetration resistance (PR), soil- water retention curves (WRC), and soil thin sections were used to characterize tillage effects on soil structure, saturated hydraulic conductivity (Ksat), and rooting environment. Undisturbed cores (5 cm dia. and length) were sampled from tracked and non-tracked interrows of three tillages (moldboard, chisel, and no till) on a Webster clay loam. Measurements on each core were: Ksat, (falling head), WRC (Tempe cells, 1- 80 k Pa), and PR recorded at 0.1 mm spacing along the core vertical axis using an INSTRON testing machine. Thin sections were prepared from 24 cores pending fractal characterization. Ksat, parameters from WRC, and roughness of PR trace were all sensitive to tillage and tracking. Interrelations of these parameters from Ksat and WRC generalized in a Kozeny-Carman relation characterized response of measured hydraulic properties to tillage and tracking. Then parameters obtained from semivariograms of PR roughness characterized geometry of pores and solids and predicted the measured hydraulic properties.