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September 1999
ON THE RESEARCH FRONT
Multispectral Data
for Soil Mapping: Possibilities and Limitations
E.M. Barnes and M.G. Baker
ASAE Technical Paper 99-1138
Soil maps derived from random or grid-based sampling schemes are often an important part of precision crop management. The sampling and analysis of soil to derive such maps requires a large investment of both time and money. Aerial photos have been used as a soil mapping aid for years. Research studies have shown that such an approach can be useful for defining management units in precision farming, but these studies are often limited to a single field, not an entire farming operaiton.
The paper was presented at the 1999 ASAE annual meeting in Toronto. In this study, multispectral airborne (green, red, near-infrared and thermal) images and satellite (SPOT and Landsat TM) images were used to derive soil maps for a 700 ha research and demonstration farm in Arizona. These images were compared to soil textural analysis results from samples in the top 30-cm of the soil profile at an approximate grid spacing of 120 m.
Using spectral classification procedures on a field by field basis, it was possible to map areas of the soil textural class (ie. sandy clay loam vs. clay loam) with reasonable accuracy.
Classification procedures were also used with vegetation present over the same area later in the season. Area of low vegetative growth tended to coincide with area of higher sand content. The resulting vegetation classes can be helpful in deciding if the soil classes impact crop development enough to warrant different management practices.
Roger Brook
paper available to
MSU Extension staff on request.NEW
