Assessing changes and drivers of crop rotation patterns and their implications for nitrogen loading in the United States
Abstract
The purpose of this study was to assess the changes and drivers of crop rotation patterns in the United States and their implications to nitrogen loading using principally the Cropland Data Layers (CDL) produced by the United States Department of Agriculture (USDA). We determined the temporal changes for different crops in the United States using different time periods from 2003 to 2011. Annual, biannual, and four-year rotation patterns were quantified and the trends of monocultural cropping practices were analyzed. The price of crops, changes in policies and expansion of ethanol production were found to contribute to the observed shift in crop rotation strategies. The impact of ethanol plants on corn monoculture was analyzed using different sized buffers and a continuous distance raster. We found that the closer to an ethanol plant, the higher likelihood that corn is planted continuously. The results also showed the direct effect of policy changes as well as changes in crop prices. With the increase in corn monoculture there is an increase in the required amount of applied nitrogen fertilizer to attain desired yields. We developed a model based on the corn yield potential of different soils combined with the recommended amount of applied nitrogen for different corn rotation practices at a national scale from 2009 to 2011. Our results were within 1 percent of National Agricultural Statistic Services (NASS) estimated nitrogen use for corn in 2009 and 2010. The model allowed us to spatially determine the distribution of nitrogen used for corn growth as well as to create scenarios to simulate the potential changes to nitrogen loading if all corn was grown in rotation or if all corn was grown in monoculture. We found that changes in crop rotations can have as much if not greater impact on the total amount of recommended nitrogen applied for corn production as the increased nitrogen from the yearly growth in corn production. Using the nitrogen model, we developed a user interface that allows a land manager or farmer to select their area of interest. The interface calculates the contribution to the total applied nitrogen within each intersected 12 digit hydrologic unit from a selected area of interest and the desired rotation practice. The interface then determines how much nitrogen would be used if the manager changes their rotation practices.
Degree
M.S.
Advisors
Pijanowski, Purdue University.
Subject Area
Agronomy|Geographic information science|Natural Resource Management
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.