Phosphorus leaching risk from black soil increased due to conversion of arid agricultural land to paddy land in northeast China

Chemical and Biological Technologies in Agriculture

Table 1 Soil properties distribution with profile depth under arid agricultural soils and paddy soils

Land use	Profile depth	pH	OM	TN	C:N	C:P	N:P
Land use	(cm)	(−)	(%)	(mg kg⁻¹)	(−)
Arid agricultural soils	0–20	6.43 ± 0.94a*^†	5.42 ± 0.79a	2648.4 ± 790.0a	11.94 ± 1.50a	24.04 ± 7.66a**	2.01 ± 0.61a*
	20–40	6.45 ± 0.75a	4.49 ± 1.06b	2036.3 ± 807.2ab	13.51 ± 2.42ab	25.13 ± 5.58a*	1.88 ± 0.32a*
	40–60	6.23 ± 0.64a	3.19 ± 1.17c*	1508.3 ± 853.6b	15.48 ± 3.21b	27.08 ± 7.10a	1.78 ± 0.45a
Paddy soils	0–20	6.05 ± 0.48a*	5.37 ± 0.83a	2480.2 ± 775.7a	13.04 ± 2.01a	34.19 ± 6.34a**	2.62 ± 0.24a*
	20–40	6.32 ± 0.48b	4.22 ± 1.03b	1821.6 ± 1057.1a	15.01 ± 4.21a	30.35 ± 4.13ab*	2.20 ± 0.79ab*
	40–60	6.37 ± 0.46bc	2.68 ± 0.70c*	946.7 ± 224.0b	16.82 ± 1.90b	28.51 ± 5.30b	1.70 ± 0.31b
Analysis of variance (P value)
Land use		0.177	0.026	0.147	0.073	0.002	0.034
Profile depth		0.411	< 0.001	< 0.001	0.001	0.753	0.003
Land use × profile depth		0.054	0.317	0.716	0.975	0.115	0.112

^†Means ± SD followed by a different lowercase letter indicate significant difference from different profile depth in the same land use
*, **indicate significant difference in the same soil depth between arid agricultural soils and paddy soils at p < 0.05 and p < 0.01, respectively