@article {KNZ00532,
	title = {Biological properties of soil and subsurface sediments under abandoned pasture and cropland},
	journal = {Soil Biology \&amp; Biochemistry},
	volume = {28},
	year = {1996},
	pages = {837 -846},
	abstract = {Little is known about the effects of most surface land-use practices on shallow subsurface microbial communities. We analyzed duplicate cores taken aseptically from up to 10 m depth from unconsolidated valley sediments (soils) beneath an abandoned pasture reverting to tall grass prairie and cropland. Both profiles had similar soil texture, with moderately higher silt under cropland and a slight decrease in clay with depth. Soluble organic C was about two times higher in the grassland site and dissolved O2 was about 8\% lower compared with the cropland site. Water content and C-to-N ratios were greatest at the grassland surface but were less in the grassland than the cropland site within 2 m depth. In general, numbers of aerobic heterotrophic bacteria and protozoa decreased with depth until the saturated zone (4.3 m in grassland and 5.3 m in the cropland site). Bacterial numbers as determined by plate counts were about 10-fold less at the groundwater interface than in the surface soils at both sites. Direct microscopic counts of total bacteria were approximately the same in the surface soil and the sediments at the top of the water table at both sites. The top of the water table generally did not exhibit elevated microbial biomass or activity relative to deeper sediments. There was no significant relationship between protozoan numbers and microbial thymidine uptake at the cropland site, but a negative relationship was observed at the grassland site. The data suggest that cultivation may affect microbial biomass and activity in the subsurface, as well as community interactions between protozoa and bacteria.},
	keywords = {LTER-KNZ},
	doi = {10.1016/0038-0717(96)00057-0},
	author = {W. K. Dodds and Banks, M.K. and Clenan, C.S. and C. W. Rice and Sotomayor, D. and Strauss, E.A. and Yu, W.}
}
@article {KNZ00526,
	title = {Optimal staining and sample storage time for direct microscopic enumeration of total and active bacteria in soil with two fluorescent dyes},
	journal = {Applied and Environmental Microbiology},
	volume = {61},
	year = {1995},
	pages = {3367 -3372},
	abstract = {Direct counting techniques, first developed for aquatic samples, can be used to enumerate bacteria in soil and groundwater sediments. Two fluorescent dyes, 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) for actively respiring bacteria and 4(prm1),6-diamidino-2-phenylindole (DAPI) for total bacteria, were tested for their usefulness in epifluorescent direct bacterial enumeration in soil. Both dyes can be used for the same soil sample without affecting enumeration results. Staining for 8 h with CTC and for 40 min with DAPI resulted in maximum numbers of stained cells. The optimal DAPI staining concentration is 10 mg liter(sup-1). After preparation, slides should be stored at 4(deg)C and counted within 2 days for CTC and within 24 h for DAPI. Sodium PP(infi) or sodium chloride solutions were used to desorb bacteria from soil prior to counting. Counts were significantly higher when sodium chloride was used.},
	keywords = {LTER-KNZ},
	url = {http://aem.asm.org/content/61/9/3367.short},
	author = {Yu, W. and W. K. Dodds and Banks, M.K. and Skalsky, J. and Strauss, E.A.}
}
