Table 1.

Descriptive statistics of the soil attributes.

Attributes	Year	Minimum	Maximum	Range	CV%	Mean ± SD	Skewness	Kurtosis	K-Sp
pH	2008	4.09	7.58	3.49	13.07	5.51 ± 0.72b	0.24	− 0.24	0.01 (0.20)
	2013	4.26	7.12	2.86	10.92	5.31 ± 0.58c	0.04	− 0.23	< 0.01 (0.20)
	2018	4.50	7.35	2.85	10.23	5.77 ± 0.59a	0.02	− 0.14	< 0.01 (0.20)
AN (mg kg−1)	2008	83.69	375.10	291.41	31.97	190.08 ± 60.76a	− 0.02	− 0.35	0.03 (0.20)
	2013	36.21	348.30	312.09	32.21	171.12 ± 55.12b	0.01	− 0.13	< 0.01 (0.20)
	2018	24.50	147.31	122.81	32.54	71.89 ± 23.39c	− 0.12	0.15	< 0.01 (0.20)
AP (mg kg−1)	2008	0.04	21.20	21.16	129.60	3.75 ± 4.86b	0.02	− 0.41	< 0.01 (0.20)
	2013	0.10	15.84	15.74	82.50	4.40 ± 3.63a	− 0.69	1.12	< 0.01 (0.20)
	2018	0.06	15.44	15.38	91.25	4.00 ± 3.65ab	0.06	− 0.50	< 0.01 (0.20)
AK (mg kg−1)	2008	31.21	246.09	214.88	46.86	101.37 ± 47.50a	0.06	− 0.50	< 0.01 (0.20)
	2013	5.96	140.08	134.12	54.79	50.98 ± 27.93b	0.16	− 0.31	< 0.010 (0.20)
	2018	22.06	340.39	318.33	60.78	114.60 ± 69.65a	− 0.05	− 0.75	< 0.01 (0.10)
SOC (g kg−1)	2008	3.06	42.42	39.36	40.28	18.32 ± 7.38b	− 0.40	0.69	< 0.01 (0.20)
	2013	6.06	38.66	32.60	34.62	18.34 ± 6.35b	− 0.15	− 0.05	< 0.01 (0.20)
	2018	3.14	46.96	43.82	38.92	21.30 ± 8.29a	− 0.74	1.29	0.03 (0.08)

AN available nitrogen, AP available phosphorus, AK available potassium, SOC soil organic carbon.

Different letters in the same variable indicate significant differences among years at P < 0.05 level. CV: coefficient of variation; K-S_p: significance level of Kolmogorov–Smirnov test for normality. The K-Sp values in brackets were calculated after transformation.