Characterizing Vertical Tillage Residue-Management Implements Impact On Crop Residue and Soil Disturbance.

Corn producers have drastically reduced tillage to save soil, time and fuel.  Some use one-pass no-till planting systems.   Others desire more residue sizing or soil mixing; yet need to maintain soil conservation benefits of high residue planting systems.   Vertical tillage implements are designed to size and distribute residue, and conduct shallow tillage.  Some corn producers use vertical tillage prior to planting because current corn hybrids have slow decomposing stalks; others need to incorporate livestock manure, lime or other nutrients.

The use of vertical tillage implements was studied on five western Wisconsin farms.  Crop residue ground cover and soil disturbance measurements were conducted on fourteen fields, after an initial tillage pass before planting, spring 2010.  Observed machines typically had two gangs of off-set fluted coulters with rolling spike harrow and basket rear attachments.

Conservative operation of these implements created two inch wide by two inch deep tillage slots every five inches across fields.  Fields of multi-year corn on silt loam soils where one-pass vertical tillage was conducted routinely showed 80% surface residue remaining and up to 80% of prior year corn roots still intact, completely anchored into the soil.  Soil disturbance increased with coarser textured soil, deeper operation, more aggressive coulters, and thin stemmed prior year crops like soybeans or alfalfa.

When using the NRCS-RUSLE2 soil loss model, conservation professionals piece together tillage operations like “coulter cart, rotary harrow, rolling basket or light finishing tandem disk” to assign soil disturbance, and residue flattening and burial characteristics to vertical tillage implements.  Results from this study will be used to train soil conservation professionals and crop consultants who evaluate fields tilled with vertical tillage implements and need to pick representative RUSLE2 tillage intensities to accurately document soil loss estimates for crop producers.