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United States Department of Agriculture

Agricultural Research Service

Title: Spatial Analysis of Soil Fertility Parameters

Authors
item CAMBARDELLA, CYNTHIA
item KARLEN, DOUGLAS

Submitted to: Precision Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 22, 1998
Publication Date: N/A

Interpretive Summary: Precision agriculture will require data on the spatial distribution of soil properties that are important for crop production. This study examined the spatial pattern of nine soil properties for a conventionally managed system and an alternative system that used crop rotations and organic nutrient sources. The specific soil properties that were strongly correlated and the maximum distance to which they were correlated (range of correlation) differed for the two farming systems. The spatial patterns observed for the alternative field were related to the long-term application of manure/sludge as a nutrient source, and placing the sampling points closer together at this site will improve the quality of information. In contrast, a sampling grid, with points spaced further apart, would be adequate for the conventional field. These results show that agricultural management affects the types of soil properties that are strongly spatially related and the sample spacing requirements of these properties. This knowledge is important for developing field sampling strategies for precision agriculture.

Technical Abstract: Precision agriculture will require accurate databases that include information on the spatial distribution of soil properties that are important for crop production. This study examined the spatial pattern of nine soil properties in two adjacent fields, a conventionally managed corn-soybean field and an alternatively managed system based on a five-year crop rotation and organic nutrient sources. We established a sampling grid in each of the fields and collected soil cores to a depth of 30 cm. The specific soil properties that were strongly spatially correlated (low nugget variance/total variance ratio) and the maximum distance to which they were correlated (range) differed for the two farming systems. Soil pH, extractable Ca, total organic C and total N were strongly spatially correlated for the conventionally managed field, and range values for these soil properties were greater than 182 m. Soil inorganic P and extractable Mg were strongly spatially correlated for the alternatively managed field, and the range of correlation for both variables was less than 100 m. The low nugget/total variance ratios and small range values for the two properties suggest the distributions are patchy. The patchy pattern of P and Mg may be related to long-term application of manure/sludge as a nutrient source at this site. Since most of the variance is structural for the alternative field, placing the sampling points closer together will improve data precision. In contrast, a relatively coarse sampling grid, with fewer soil sampling points spaced further apart, would be adequate for the conventional field. This knowledge is important for developing field sampling strategies for precision agriculture.

Last Modified: 7/25/2014