Effect of tillage and irrigation on southeastern U.S. soils under cellulosic sorghum feedstock production

Authors: ROCATELI, ALEXANDRE - Oklahoma State University; RAPER, RANDY - Oklahoma State University; ARRIAGA, FRANCISCO - University Of Wisconsin; Balkcom, Kipling

Submitted to: Archives of Agronomy and Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2020
Publication Date: 8/7/2020
Citation: Rocateli, A.C., Raper, R.L., Arriaga, F., Balkcom, K.S. 2020. Effect of tillage and irrigation on southeastern U.S. soils under cellulosic sorghum feedstock production. Archives of Agronomy and Soil Science . https://doi.org/10.1080/03650340.2020.1802430.
DOI: https://doi.org/10.1080/03650340.2020.1802430

Interpretive Summary: Sorghum may be a good cellulosic material for bioenergy production because it can be cultivated in current row-crop systems. However, the production of sorghum for bioenergy and its impacts on Southeastern U.S. soils should be investigated to determine the most environmentally sustainable system. Scientists currently at Oklahoma State Univ and Univ. of Wisconsin in conjunction with USDA in Auburn, AL evaluated tillage (conventional vs. conservation systems), and irrigation effects (irrigated vs. non-irrigated) on soil characteristics when producing cellulosic feedstock from three forage sorghums and one forage corn (control) in 2008 and 2009. Soil organic carbon (SOC) increased at a depth of 0.10–0.15 m, but decreased at a depth of 0.40–0.45 m with higher losses being found using conventional tillage as opposed to conservation tillage. Total nitrogen (TN) and bulk density (Bd) increased at all evaluated soil depths (0–0.50 m) after 2 years. Conventional tillage plots also showed higher Bd at 0.15–0.30 m. Higher Bd in conventional tillage plots might restrict water drainage which could explain higher volumetric soil water content (SWC) at 0.10, 0.20 and 0.40 m soil depths. Results suggest that the amount of sorghum cellulosic feedstock harvested must be restrained, allowing biofuel production without jeopardizing soil and environmental quality. Further research must be developed to elucidate the appropriate harvestable amounts of sorghum cellulosic feedstock without causing negative impacts in agricultural soils.

Technical Abstract: Sorghum may be a good cellulosic material for bioenergy production because it can be cultivated in current row-crop systems. However, the production of sorghum for bioenergy and its impacts on Southeastern U.S. soils should be investigated to determine the most environmentally sustainable system. The objective of this study was to evaluate tillage (conventional vs. conservation systems), and irrigation effect (irrigated vs. non-irrigated) on soil characteristics when producing cellulosic feedstock from three forage sorghums and one forage corn (control) in 2008 and 2009. Results showed that soil organic carbon (SOC) increased at a depth of 0.10–0.15 m, but decreased at a depth of 0.40–0.45 m with higher losses being found using conventional tillage as opposed to conservation tillage. Total nitrogen (TN) and bulk density (Bd) increased at all evaluated soil depths (0–0.50 m) after 2 years. Conventional tillage plots also showed higher Bd at 0.15–0.30 m. Higher Bd in conventional tillage plots might restrict water drainage which could explain higher volumetric soil water content (SWC) at 0.10, 0.20 and 0.40 m soil depths. Cone Index (CI) values also showed improved soil conditions at in-row positions for conservation plots.