Modeling Soil Organic Carbon in the Soil and Water Assessment Tool (SWAT)
Background
During the past 25 years, the grain sorghum acreage in the U.S. has ranged from 15 to 18 million acres per year. Grain sorghum acreage is somewhat greater than acreages for oats and barley, but considerably less than the land area planted to corn, wheat, and soybeans (Carter 1989) .
To produce ethanol from grain sorghum it is first dissolved into sugar. Then the sugar is fed to microbes which converts it into alcohol and carbon dioxide. The alcohol is then filtered into the correct concentration to obtain ethanol.
When grain sorghum is harvested for ethanol conversion the stover is collected from the field. This ensures that the most ethanol per acre will be produced, but this also jeopardizes bare soil to the harsh environment.
Also by removing all the organic matter from the soil surface very little organic carbon can be replenished from the crop. If there is no crop residue left after harvesting, the soil will be limited on the amount of carbon it contains affecting the health of the soil, plants, microbes, and animals living in the terrestrial ecosystem.
Study Area
The Wildcat Creek watershed (HUC 1027010102) is located in Southern Riley County and Northern Geary County and is approximately 24,774 hectares
(Figure 1).
The most common soil in the basin was type D which is soil that drains poorly and has a clayey texture.
The major land cover of McDowell Creek Basin
- 68% rangeland/grassland
- 10 % deciduous
- 5 % agricultural low row crops (ex. soybeans)
The remaining land is a multiple of different lands that make up < 1% each
The major slopes of McDowell Creek Basin
- 62% (5-8%)
- 23% (2-5%)
- 15% (< 2%)
