HR: 11:50h
AN: B42A-06    [Abstracts]
TI: Using the USDA Weekly Crop Progress Record to Document Trends in Corn Planting Date From 1979 to 2005
AU: * Kucharik, C J
EM: kucharik@wisc.edu
AF: Center for Sustainability and the Global Environment University of Wisconsin-Madison, 1710 University Avenue, Madison, WI 53726 United States
AB: Agriculture is a dominant driver of land surface phenology in the United States Corn Belt. The timing of planting and harvest, along with the rate of plant development, are influenced by crop type, technology, land management decisions, and weather and soil conditions. Collectively, these integrated factors affect the spatial and temporal spectral signature of crops captured by remote sensing. While many studies have used the historical satellite record of vegetation activity to detect changes across the land surface, there has been less emphasis on using ground-based or remote sensing data to depict the contemporary phenology of individual US agro-ecosystems. The objectives of this study were twofold: (1) demonstrate how weekly USDA-NASS 'Crop Progress' data and 'Weekly Weather and Crop Bulletins' could be useful to remote sensing science when characterizing changing land surface phenology over the US; and (2) quantify long-term trends in corn planting progress from 1979 to 2005 across 12 states in the US Corn Belt. Examination of the weekly NASS crop progress data shows that the initiation of corn planting has become significantly (P < 0.01) earlier by 6 to 24 days since 1979, potentially contributing to about 10% to 64% of the linear increase in corn yields during this period. The magnitude of earlier planting date trend varies regionally, and not all of this change can be attributed to an earlier arrival of spring or warmer springtime temperatures. Rather, the change appears to be related to increased farmer planting efficiency in spring attributed to the increased adoption of no-tillage or reduced-tillage practices and plowing soils in fall. Regardless of the exact cause of this trend, we have a legitimate reason to suspect that 'greening' of the Corn Belt since about 1980, according to remote sensing observations, is not entirely due to climate change, but rather arises from human land-use change in combination with climate factors. In the future, crop progress data may provide an ideal blueprint for selecting the ideal MODIS scene (i.e., 8-day period) that can separate various crop phenologies (e.g., corn vs. soybean) at high resolution, and offer a means to help validate or parameterize ecosystem model algorithms.
DE: 0402 Agricultural systems
DE: 0480 Remote sensing
DE: 1630 Impacts of global change (1225)
DE: 1632 Land cover change
SC: Biogeosciences [B]
MN: Fall Meeting 2005