Multiple benefits of greenhouse gas reduction through inclusion of perennials in cropping systems

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Increasing concentrations of greenhouse gases (GHG) in the atmosphere are believed to be the cause of current realized global warming. Agriculture is an important source of greenhouses, particularly nitrous oxide. Like all sectors of the economy, agriculture is expected to reduce its emissions. Perennial crops are important for livestock feed and will increasingly be used for biofuel production. This research program examines the multiple benefits of inclusion of perennials in crop rotations to reduce greenhouse gas emissions and increase soil health. Perennials utilize nitrogen fertilizers and manures better than annual crops, which could reduce nitrous oxide emissions. Perennials may also lower the amount of fertilizer nitrogen lost to the atmosphere as the non-greenhouse gas, nitrogen gas. Lowering the loss of fertilizer nitrogen increases profitability and avoids direct greenhouse gas emissions from soil and emissions related to manufacturing and transporation of fertilizer. Legume perennials supply their own nitrogen nutrition and are not dependent upon nitrogen fertilizer addition, this reduces greenhouse gas emissions from fertilizers associated with direct emissions from soil, manufacturing and transportation, however emissions of nitrous oxide from legume produced nitrogen is uncertain. Perennials have more extensive rooting systems than annual crops, storing more carbon in soil thus lowering emissions of greenhouse gases. In the long term, perennial cover alters soil food webs to more diverse organisms, particularly beneficial fungi associated with the roots (called arbuscular mycorrhizal fungi) and higher trophic soil organisms, their effect on shorter terms of 3 years within cropping systems is uncertain. Recently it has been demonstrated that these fungi provide a form of carbon, call glomalin, that builds soil organic matter and improves soil structure. This program aims to discover if conversion from the perennial to annual phase in crop rotations, releases carbon and nitrogen stored in soil as greenhouse gases. Similarly, the program aims to resolved if glomalin and diversity of soil food webs is retained upon conversion from perennial to annual phases of cropping systems thus improving soil health.