HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wollum, A. G. Articles by Cassel, D. K. Search for Related Content PubMed Articles by Wollum, A. G., II Articles by Cassel, D. K. Agricola Articles by Wollum, A. G. Articles by Cassel, D. K.

Spatial Variability of Rhizobium japonicum in Two North Carolina Soils¹

ABSTRACT

The spatial variability of Rhizobium japonicum populations was evaluated for two soils on the Coastal Plain of North Carolina. The Nahunta soil (fine-silty, siliceous, thermic Arenic Paleudults) was somewhat poorly drained and had an organic matter content of 20 g kg^–1 whereas the Pocalla soil (loamy, siliceous, thermic, Arenic Paleudults) was well drained and had 10 g kg^–1 organic matter. One hundred and five soil samples from the Ap horizon were collected from an apparently uniform 18-m by 18-m area at each site and were subjected to analysis by the plant infectivity—most-probable-number (MPN) technique to determine the number of rhizobia. The log₁₀ MPN (log MPN) of R. japonicum varied from 2.63 to 7.03 g^–1 soil; mean log MPN values were 4.10 and 6.07 g^–1 soil for Pocalla and Nahunta, respectively. Semivariograms for sample separation distances (h) < 2 m at each site were developed from soil samples collected on transects (fences). Semivariograms for h 3 m were developed using data collected on a 3-m grid. Analysis of the semivariograms constructed from the log MPN data indicated a different variance structure at each site. Moreover, the variance structure for log MPN was found to be directional, i.e., it was different in the direction "parallel to the row" compared to the direction "perpendicular to the row." For the Pocalla soil the semivariance in the "down-the-row" direction was greater for values of h < 1.05 m than it was for h 3 m. This apparent discrepancy is thought to be due to selection of the transect from which the 0.2-m spaced samples were collected in a region of the field which is not typical of the field as a whole. This result demonstrates the importance of using a sampling regime which is not biased toward one particular area of a field. Root densities, inherent soil properties, seasonality, and management practices are possible contributors to the subtle changes in rhizobia populations that were observed.

¹ Contribution from the Dep. of Soil Science, North Carolina State Univ. Paper No. 8959 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27650.

² Professors of Soil Science, North Carolina State Univ., Raleigh, NC 27650.

Received for publication September 6, 1983. Accepted for publication March 20, 1984.

This article has been cited by other articles:

				B. J. Horvath, A. N. Kravchenko, G. P. Robertson, and J. M. Vargas Jr. Geostatistical Analysis of Dollar Spot Epidemics Occurring on a Mixed Sward of Creeping Bentgrass and Annual Bluegrass Crop Sci., May 31, 2007; 47(3): 1206 - 1216. [Abstract] [Full Text] [PDF]

				M. Byappanahalli, M. Fowler, D. Shively, and R. Whitman Ubiquity and Persistence of Escherichia coli in a Midwestern Coastal Stream Appl. Envir. Microbiol., August 1, 2003; 69(8): 4549 - 4555. [Abstract] [Full Text] [PDF]