Design, treatments, and vegetation measurements
This study was conducted on the Jornada Experimental Range (JER) from
1988-89. The objective of this study was to measure nodulating
rhizobia of honey mesquite shrubs (Prosopis glandulosa) of irrigated
treatments and non-irrigated controls. Five mesquite dunes were
irrigated by pumping water from storage tank located 200 m from the
site. Water was applied to the dunes with an overhead sprinkler (later
replaced by a drip irrigation system to minimize wind drift) located
at the apex of each dune. Irrigation began in March with approximately
2.5 cm applied 2-3 times/week for 6 weeks to initially wet the dry
soil. Thereafter high water availability was maintained by weekly
irrigation. Five non-irrigated dunes served as control. Soil samples
were collected with hand augers under each mesquite to three depths,
0-50 and 50-100, and 100-150cm. Soil samples were placed in plastic
bags, tied, and stored in portable coolers. Concentrations of
mesquite-nodulating rhizobia in field-moist soil samples were
estimated using the plant-infection, most probable number (MPN)
technique (Vincent 1970).
References
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Vincent, J. M. 1970. A manual for the practical study of root-nodule
bacteria. IBP Handbook 15. Blackwell Scientific Publi., Oxford,
England.