Fronning, Bradley (Michigan State University, 286A Plant and Soil Sciences Building, Michigan St, East Lansing, MI, 48824; Phone: 517-355-0271; Email: fronning@msu.edu)

Carbon Sequestration Practices in Silage Corn - Soybean Cropping Systems in Michigan

B.E. Fronning *, K.D. Thelen, D.H. Min

Research was conducted over three years (2002-2004) at Michigan State University in East Lansing, MI (N 42.42, W 84.28) and at the Upper Peninsula Experiment Station near Chatham, MI (N 46.29, W 86.76) to evaluate the effectiveness of cover crops and manure systems for carbon sequestration at different latitudes. The experiment consisted of six treatments applied to soybean and silage corn at East Lansing: composted manure, fresh manure, winter rye cover crop, winter rye + composted manure, winter rye + fresh manure, and an untreated check. Treatments at Chatham were applied to silage corn and forage soybean in 2002 and 2004 and silage corn in 2003. Winter rye cover crop failed in 2002 at Chatham so treatments containing winter rye were changed to include forage soybean instead. In 2002 and 2004 treatments consisted of composted manure, fresh liquid manure, and an untreated check applied to silage corn and forage soybean. In 2003 a winter rye cover crop was established so the treatments were composted manure, fresh liquid manure, winter rye cover crop, composted manure + winter rye, fresh liquid manure + winter rye, and an untreated check. Soil samples were collected in the spring of every year plus the fall of 2004 to determine, total carbon, total nitrogen, phosphorous, particulate organic matter, bulk density, and pH. A gas chamber was placed in each plot to measure the flux of greenhouse gases in an enclosed system. Over 5400 total gas samples were collected over the three year period between both locations. Winter rye alone and the untreated check were the only treatments which failed to increase soil carbon levels at East Lansing between the springs of 2002 and 2004. Treatments containing composted manure increased soil carbon levels more than those containing fresh manure. Winter rye + fresh manure was the only treatment at Chatham which did not result in increased soil carbon levels. Similar to East Lansing, treatments containing composted manure appeared to increase soil carbon levels faster. Efficiency of these treatments in sequestering carbon was affected by latitude. Less applied carbon was required at Chatham to increase soil carbon than at East Lansing. Gas flux was affected by treatments at certain times of the growing season. Treatments had minimal affects on crop yields at both locations.