|Evans, Samuel - RETIRED|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 9, 1998
Publication Date: N/A
Technical Abstract: Mankind is dependent on quality soil resources for ensuring sufficient food to support life. Quantifying soil quality is necessary for defining and managing the soil. Soil organic carbon is one of the indicators suggested for quantifying soil quality. This work evaluated the impact of 30 years of continuous corn (Zea maize L.) silage removal versus grain removal only on soil carbon. A secondary objective was to measure tillage-induced CO2 loss from soil using a portable gas exchange chamber after moldboard plowing. Continuous corn was grown under low and high fertility where one-half of the treatments had silage removed and the other half had only grain removed and stover returned. Conventional moldboard plow tillage was used, typically in the fall. Soil carbon and nitrogen analyses were done using standard analytical techniques. The 24-hour cumulative CO2 losses were not significantly different between annual silage and grain removal treatments. There was no treatment difference in total carbon, nitrogen or C:N ratio. All four treatments showed soil carbon decreases and had the same organic carbon content of 21.9 g kg-1 in the 0-15 cm depth. The cumulative carbon removed as silage compared to treatments where stover was returned at both levels of fertility caused no differences in organic carbon. Intensive tillage by the moldboard plow caused rapid residue decomposition that masked fertility effects on soil carbon. New approaches to enhance carbon sequestration are needed in agricultural systems that require less tillage and allow a positive buildup in organic matter and the associated enhancement in soil quality.