TABLE 1.

Yield and apparent purity of DNA extracted from three different soils^a

Soil and methodb	Yield (μg/g dry soil)	OD260/OD280c
B
S	4.54 ± 0.62	1.0
P	14.58 ± 0.58	1.65
C	1.13 ± 0.15	1.22
V
S	6.33 ± 1.86	1.4
P	16.45 ± 3.97	1.6
C	5.25 ± 2.42	1.5
K
S	3.30 ± 1.45	1.6
P	2.69 ± 0.08	1.72
C	2.29 ± 0.79	1.7

^aThe Ultraclean (U) method yielded 200 to 250 ng/g soil throughout. Triplicate samples obtained from three plots were analyzed.

^bSoils: B, Buinen; V, Valthermond; and K, Kollumerwaard. Methods: S, Smalla et al. (14); P, Powersoil (MoBio); C, CIAT (described in this study; see the supplemental material).

^cOD₂₆₀/OD₂₈₀, optical density at 260 nm over that at 280 nm.