No-till Bioenergy Cropping Systems Effect on Soil Gas Dynamics.

Bioenergy cropping systems have been proposed as a way to enhance United States energy security.  However, research on soil quality, such as the effects of maize stover harvesting on soil aeration and the relationships to soil structure and water, associated with bioenergy cropping systems has been limited.  The limited amount of data available on this subject creates concerns among the scientific community as removing additional aboveground biomass from primary production systems may impact soil quality. Since soil aeration properties are dynamic, high-resolution data are needed to capture their temporal relations and variability.  The objective of this study is to quantify and test relationships among high-resolution changes of soil physical properties and conditions to soil-gas composition and efflux.  Near Ames, Iowa, six no-till cropping systems of mixed prairie (nitrogen fertilized and unfertilized), continuous maize with 50 % stover removal (with and without cover crop), and maize-soybean rotation (each crop type grown each year) was initiated with four replications in a randomized complete block design.  Plots were instrumented with sensors to measure CO₂ and O₂ concentration profiles, and weekly CO₂ emissions were measured. Results of soil CO₂ and O₂ concentration profiles, CO₂ efflux, matric potential, water content and temperature profiles, air permeability, aggregate stability and size distributions, and bulk density will be presented.