Submitted to: Clean Water Clean Environment 21st Century Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/10/1995
Publication Date: N/A
Interpretive Summary: Tillage systems must be included as a best management practice to control agrichemical losses from the target site. Actual field tests of tillage systems effects on agrichemical losses indicate that other factors (weather, soil properties in the tilled layer and subsoil, crop residue management, physico-chemical property of the agrichemical) may change response to a tillage system. The reported research demonstrated a graphic model of a tilled soil into which measurements generate a consensus of relations available for computer simulating water flow and agrichemical transport into runoff, soil erosion, and internal movement to groundwater. These simulations are site-specific because the natural features of the site are used as input for the simulation. This graphic model can also be used by research and extension specialists to provide generic conclusions in the absence of simulation.
Technical Abstract: The tillage systems interaction with natural features and climate/weather of a specific site dominates/controls runoff, soil erosion, and internal transport to groundwater. Consequently, best management tillage systems are most likely to be developed using a simulation of water flow and agrichemical transport that requires site specific inputs related to the tillage and the natural features. Repeated trials demonstrated that crop residue remaining on the surface, depth distribution and cluster of inforporated residue, tillage pans intensity and location, as well as macropore position and longevity were all tillage-tool specific. The moldboard buried nearly all of the residue below 10 cm; the disc left a different distribution than sweep or chisel above 10cm. Because of the distinct moldboard inversion, old residue is above 10 cm while new residue is below 10 cm; new and old residue are always commingled above 10 cm when using chisel/disc/sweep. Secondary tillage is rarely deeper than 10 cm. Method of agrichemicals application was expected to control exposure to macropores. A graphic assembly of these observations generically predicted bypass flow, runoff/erosion potential, surface seal, and herbicide activity.