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United States Department of Agriculture

Agricultural Research Service

Title: Yield Variability Within a Central Iowa Field

Authors
item Colvin, Thomas
item Jaynes, Dan
item Karlen, Douglas
item Laird, David
item Ambuel, Jack - AG. LEADER TECHNOLOGY

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 28, 1997
Publication Date: N/A

Interpretive Summary: New technology is available for managing fields as a collection of locations instead of as a single unit. Farmers will be able to more closely match inputs to crop needs. This should be an economic benefit to farmers, it should provide opportunities for agri-business to provide services to farmers and it should help agriculture be more sustainable and environmentally friendly, which is of benefit to the whole country. Effective use of this technology will require knowledge of the patterns of plant response (yield) across fields. This study used 228 small plot yields along 8 transects in a 40 acre field to measure yield variability. Yields showed a great deal of variability among locations within the field each year. There was also much variability within a location when yields were compared among years. It will not be possible to completely understand the relationships between individual locations within a single field in one or two years to effectively address yield variation. In fact, it appears that more than 10 years of information may be needed. Even then, management may need to be based on probability rather than on certainty of plant response. The National Soil Tilth Laboratory currently has 8 years of yield variability data on this field and is working to understand the relationship between soil, climate, and plant information. Data collection and analysis is planned to continue.

Technical Abstract: Technologies to support precision farming (PF) began to emerge in 1989 when the Global Positioning System (GPS) became available to a limited extent. One major class of information that is missing is a method for determining how much material to apply or what action to take as a result of a specific condition at any position within the field. Developing this information will require knowing the spatial and temporal variability of plant response This field study was designed to quantify yield variability within a 16 ha field which has had consistent practices for several years. Crop yields showed a coefficient of variability ranging from near 12% in 1989 and 1992 to over 30% in 1990 and 1993. Relative yield rankings between specific locations were not stable after 6 years when recalculated each year. Perhaps stable patterns will eventually emerge, but the time frame for this to occur may be quite long. Overall, this study suggests that implementation of PF practices within the Clarion-Nicollet-Webster soil association area will reveal both difficulties and opportunities.

Last Modified: 12/20/2014
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