Soil Phosphorus Dynamics of Wheat-Based Cropping Systems in the Semiarid Region of Argentina

Table 2

Soil organic carbon (SOC), organic (Po), inorganic (Pi), total extractable (Pte), total and extractable phosphorus (Pe), Po : (Po + Pi) relationships, and pH of different cropping systems (CS).

Year	CS	SOC	Po	Pi	Po : (Po + Pi)	Pte	Pt	Pe	pH
		%	mg kg^−1		mg kg^−1
0	Ref	1.28	189.0	328.0	0.37	529.0	562.1	30.9	6.7
9	WG	1.13^a*	77.7^a**	294.7^a*	0.20^a**	289.6^b**	412.2^b*	14.3^b**	6.8^a ns
	WW	0.89^b**	50.4^b**	172.0^b**	0.22^a**	230.0^b**	396.3^b*	11.7^b**	6.6^b ns
	WL	1.14^a*	82.2^a**	290.5^a*	0.22^a**	417.3^a*	456.3^a*	33.7^a ns	6.6^b ns
10	WG	1.08^a	133.7^a	231.1^a	0.37^a	396.7^a	418.0^a	10.2^b	6.4^ab
	WW	0.84^b	75.5^b	159.0^b	0.32^b	344.1^b	378.2^ab	13.1^b	6.3^b
	WL	1.11^a	107.3^ab	230.5^a	0.32^b	339.7^b	362.1^b	21.2^a	6.5^a
11	WG	1.07^a	86.7	217.5^b	0.38^a	350.2^a	440.0^a	15.7^b	6.3^a
	WW	0.85^b	84.0	176.3^c	0.32^b	316.8^b	407.2^a	18.8^b	6.3^a
	WL	1.12^a	81.5	245.7^a	0.33^b	289.7^b	328.4^b	26.0^a	6.1^b
12	WG	1.16^a	85.4	218.1^b	0.28^a	343.0^a	420.0^a	11.6^b	6.4^a
	WW	0.95^b	65.7	233.7^ab	0.22^b	365.2^a	411.3^a	27.2^a	6.1^b
	WL	1.27^a	78.3	250.2^a	0.24^b	280.1^b	321.6^b	10.4^b	6.2^b

, and ns indicate statistical differences , and not significant, respectively, between each treatment sampled in year 9 and reference soil. For SOC, each P form and pH, different letters indicate differences among treatments in each year.