Assessing Climate Variability Impact On the Threshold Level of Corn Residue Removal for Biofuel Production.

Interannual climate variability plays a major role of the amount of biomass and grain produced in a corn crop. Long term data of crop residues removal effects on soil biophysical properties are limited.  The objective of this study was to evaluate the impact of climate variability on corn biomass production and on threshold level of crop residue removal using the SALUS model. The model was extensively tested on soil carbon dynamics with long term observed data at the LTER site at the Kellogg Biological Station in Michigan. Different crop residue removal scenarios were simulated for 100 years of weather data to determine the effect of the removal on soil carbon and other biophysical soil properties. The scenarios were: no removal;  100% removal;  3/8 removed and 3/8 with a minimum amount of 2000 kg ha-1 retained.  The SALUS model provided excellent results when compared with field measurements of SOC and corn yield. The residue removal scenarios showed that climate variability is a crucial component to account for when corn is grown biofuel production. The number of years where the minimum threshold requirement was satisfied significantly varied among the removal scenarios and during the long term weather series.