Short-Term Impact of Winter Cover Crop Biomass Removal On Soil Physical Properties.

Rye (Secale cereale L.) is often recommended as a winter cover crop for conservation systems in the southeastern United States.  Typically, rye is terminated with a glyphosate application 2-3 weeks prior to planting a summer crop.  The glyphosate application is followed by a rolling operation to flatten the biomass and form a dense mat.  This dense mat protects the soil from erosion, conserves soil moisture, provides weed control and promotes increases in soil organic matter.  However, there is some interest in harvesting this biomass for bioenergy production or animal feed.  Although the cover would still protect the soil from erosion during the winter months, this practice can be detrimental to soil properties and crop productivity.  A study located in Central Alabama was established to study the impact of rye residue removal on soil properties and cotton (Gossypium hirsutum L.) productivity.  The residue management treatments were: no winter cover (NC), rye residue retained (RET) and rye residue removed (REM).  Removing the rye residue significantly lowered organic carbon, particulate organic matter carbon, and mineral-associated carbon in the soil compared to RET after two years.  Retaining the rye residue significantly increased infiltration  and lowered the 0-5 cm soil bulk density.  Differences in bulk density at deeper depths were small.  Soil aggregate stability was not affected by any of the three residue managements.  Seed cotton yields ranked RET>REM>NC.  It is expected that differences in soil properties between residue management treatments will be greater with time.