Submitted to: US Environment
Publication Type: Abstract Only
Publication Acceptance Date: 7/10/2003
Publication Date: 7/10/2003
Citation: OLNESS, A.E. INTENSIFICATION OF NITROGEN CYCLING FROM AGRICULTURAL LANDS: AN UNINTENDED CONSEQUENCE OF NATIONAL POLICY? AVAILABLE FROM: HTTP://WWW.USENVIRONMENT-2003.COM 
Technical Abstract: Changes in agricultural production in the US Corn Belt over the last 50 years have been quite dramatic. Increased nitrogen fertilization has been implicated as a cause of greater nitrogen in stream water concentrations. Increased nitrogen concentrations in the Mississippi watershed have, in turn, been implicated as factors in the development of larger hypoxic zones in the Gulf of Mexico. However, an inexpensive national food policy has clearly contributed to exacerbation of nitrogen movement to the Gulf of Mexico from the Corn Belt. This policy has resulted in conversion of > 6 million ha from hay production and > 12 million ha from small grain production to maize (Zea mays L.) and soybean (Glycine max L.) production. Shifting crop production has had the subtle effect of accelerating mineralization of soil organic matter and the production of nitrate-nitrogen during a time period in which no plants are available to capture the nitrogen; hence, greater leaching loss of nitrogen. Further, removal of soil cover during this critical period has contributed to soil warming which further accelerated mineralization of organic matter and production of inorganic nitrogen. Converting land, once dedicated to hay and small grain production to corn and soybean production, has accelerated soil erosion and this has also contributed organic nitrogen to streams and rivers during the fallow period. This paper discusses the factors affecting microbial mineralization of organic matter and explains how they interact to intensify nitrogen movement in the environment.