Table 1. Average total P concentration in sequentially extracted soil samples as determined in undigested, block digestion, and autoclave digestion methods in the water fraction.

Soil Series	Filtered	Extract		Block Digestion		Auto Clave
		mg kg−1
Amarillo	No	3.8	c†	11.4	a	6.2	b
	Yes	3.7	c	11.1	a	3.5	b
Barnes	No	0.7	b	14.0	a	3.7	b
	Yes	1.4	b	12.1	a	1.1	b
Brazil	No	6.3	b	18.3	a	1.7	c
	Yes	6.1	b	17.2	a	5.1	b
Clarion	No	14.6	bc	16.6	ab	6.5	d
	Yes	12.5	c	19.1	a	12.6	c
Cordova	No	11.3	a	15.9	a	9.1	a
	Yes	9.7	a	16.0	a	10.3	a
Estherville	No	8.3	c	13.6	a	8.4	bc
	Yes	6.0	c	11.3	ab	5.2	c
Fargo	No	22.9	a	20.8	a	24.1	a
	Yes	24.2	a	25.1	a	19.0	a
Formdale	No	14.3	ab	19.6	a	18.1	a
	Yes	12.4	b	20.0	a	9.1	b
Hubbard	No	10.8	c	20.9	a	18.6	a
	Yes	8.8	d	16.2	b	7.7	d
Lester	No	12.4	b	21.7	a	18.8	a
	Yes	9.8	c	20.4	a	10.4	bc
MtCarrol	No	2.2	bc	10.7	a	5.1	b
	Yes	1.3	c	10.8	a	2.1	bc
Nicollet	No	5.5	bc	16.3	a	7.9	b
	Yes	2.2	c	14.5	a	5.1	bc
Normania	No	4.6	c	12.7	a	6.4	b
	Yes	3.5	c	12.5	a	4.8	c
Pella	No	21.2	a	22.2	a	22.1	a
	Yes	17.0	a	18.5	a	16.7	a
Pullman	No	43.3	a	33.8	bc	37.3	ab
	Yes	31.7	bc	28.9	bc	25.8	c
Randall	No	24.0	a	27.0	a	23.9	a
	Yes	19.6	a	23.3	a	16.3	a
Seaton	No	6.6	b	14.6	a	12.1	a
	Yes	5.1	b	12.2	a	5.4	b
Storden	No	5.1	b	13.2	a	8.3	ab
	Yes	3.2	b	9.5	a	3.5	b
Walter	No	25.7	ab	23.7	b	29.5	a
	Yes	21.2	b	19.7	b	21.1	b
Zimmerman	No	7.9	bc	12.9	a	10.8	ab
	Yes	5.0	bc	11.6	a	6.1	c

^†Means for a soil series followed by the different letter are significantly different (P < 0.05).