Min, Doo-Hong (Michigan State University, Upper Peninsula Experiment Station, PO Box 168, Chatham,, MI, 49816; Phone: 906-439-5114; Email: mind@msu.edu)

Dairy Forage Cropping Best Management Practices: A Comparison of Soil Carbon Sequestration and Greenhouse Gas Fluxes

J.D. DeYoung, R.H. Leep, D.H.Min *, T.S. Dietz

A study was initiated in 2002 located at the Kellogg Biological Station (KBS, Hickory Corners, MI) and the Upper Peninsula Experiment Station (UPES, Chatham, MI). The objective of this study was to provide forage crop producers with information regarding the results of cropping system management decisions on the basis of soil carbon sequestration and greenhouse gas production potentials of different no-till dairy forage production systems. The study was a replicated, randomized complete block design, with no-till dairy-forage cropping system treatments. These include continuous corn, continuous alfalfa, corn-alfalfa rotation, and an alfalfa-orchardgrass mixture. Each cropping system was subjected to two levels of organic matter inputs, either no organic matter input, or organic matter input in the form of composed manure (KBS location), or dairy manure slurry (UPES location). Both forms of organic matter were applied at a rate of 3,360 kg of carbon per hectare. Data collection included forage dry matter yield, forage quality, soil greenhouse gas emissions (carbon dioxide, methane, and nitrous oxide), total soil carbon and nitrogen, particulate organic matter carbon, soil bulk density, and soil nitrate and ammonium nitrogen. Results after 3 years of cropping and organic matter treatments indicate differences in greenhouse gas emissions measured in this experiment were mainly due to soil moisture and temperature changes and only secondarily related to cropping or organic matter treatments. Soil carbon sequestration, was measured as the differences in soil particulate organic matter (POM) levels between cropping and organic matter treatments. At KBS, plots that had compost applied tended to have higher levels of POM in the top 5 cm of soil. However, these differences were not significant. At UPES, the high background levels of soil carbon made detecting any differences in POM difficult, therefore, no differences between treatments were found. There were no measured differences between the cropping or organic matter treatments and soil nitrate, ammonium, or soil bulk density.