Sewage sludge as a substitute for mineral fertilization of spinach (Spinacia oleraceae L.) at two growing periods

Figures & data

Table 1. Some physical properties of experimental soil

Depth (cm)	Sand (%)	Clay (%)	Silt (%)	Texture	pH	CaCO3 (mg kg^−1)	Total salt (%)	Organic matter (%)
0–20	26.8	34.0	39.2	Clay-silt	8.4	14	0.015	0.41
20–40	30.8	30.0	39.2	Clay-silt	8.5	12	0.015	0.30

Table 2. Some chemical properties of experimental soil

Depth (cm)	N (%)	P (mg kg^−1)	K (mg kg^−1)	Fe (mg kg^−1)	Zn (mg kg^−1)	Mn (mg kg^−1)	Cu (mg kg^−1)
0–20	0.060	3.6	285	2.7	0.6	2.6	1.1
20–40	0.050	6.0	285	0.6	0.6	1.6	1.0

Table 3. Some properties of farmyard manure and sewage sludge

Properties	Farmyard manure	Sewage sludge
Organic matter (%)	36.5	25.0
pH (1/1 water)	5.94	6.06
Total N (%)	0.45	1.30
Total P (%)	0.17	0.59
Available P (mg kg^−1)	270.0	561.0
Total K (%)	0.27	0.41
Total Ca (%)	0.62	1.72
Total Mg (%)	0.38	1.76
Total Fe (%)	0.098	1.86
Total Zn (%)	0.060	0.19
Total Mn (mg kg^−1)	220.0	402.0
Total Cu (mg kg^−1)	28.0	74.0
Total Co (mg kg^−1)	2.6	13.2
Total Ni (mg kg^−1)	Trace	12.0
Total Cr (mg kg^−1)	Trace	51.0
Total Cd (mg kg^−1)	Trace	0.73

Table 4. Effects of sewage sludge in compensation for mineral fertilizer on the yield, dry matter and nutrient content in spinach

			Treatements^1
Traits	LSD^2	Season	1	2	3	4	5	6	7	Mean	LSD^4
Yield (kg ha^−1)	6800	Spring	1710 c^3	7740 ab	10600 a	10670 a	10420 a	9330 ab	5180 ab	7950 B^5	3430
	12730	Winter	12290 c	28020 b	28770 b	34350 ab	37610 a	40770 a	15130 c	28480 A
Dry matter (g 100 g plant ^−1)	3.02	Spring	10.30 ab	11.23 b	9.00 b	8.10 b	8.07 b	9.10 b	12.80 a	9.80	NS
	3.08	Winter	10.32 b	9.86 a–c	9.21 a–c	6.83 bc	7.59 bc	6.61 c	11.91 a	9.91
N, (g 100 g plant ^–1 Dw)	0.13	Spring	3.86 e	4.58 a	3.97 d	4.26 c	4.43 b	4.61 a	3.96 d	4.24 A	0.05
	0.15	Winter	3.55 e	4.31 a	3.86 c	3.90 c	4.15 b	4.29 a	3.75 d	3.97 B
P, (g 100 g plant ^−1 DW)	0.04	Spring	0.20 e	0.41 c	0.28 d	0.40 c	0.46 b	0.49 a	0.22 e	0.35 B	0.02
	0.05	Winter	0.26 d	0.48 a	0.33 c	0.44 b	0.50 a	0.52 a	0.27 d	0.40 A
K, (g 100 g plant ^−1 DW)	0.19	Spring	3.39 d	4.72 a	4.42 b	4.82 a	4.83 a	4.81 a	4.04 c	4.43 A	0.07
	0.19	Winter	3.21 f	4.43 bc	4.05 d	4.34 c	4.53 b	4.68 a	3.76 e	4.14 B
Ca, (g 100 g plant ^−1 DW)	0.11	Spring	0.52 b	0.63 a	0.65 a	0.68 a	0.64 a	0.65 a	0.64 a	0.63 A	0.05
	0.13	Winter	0.42 b	0.64 a	0.59 a	0.61 a	0.64 a	0.58 a	0.61 a	0.58 B
Mg, (g 100 g plant ^−1 DW)	0.07	Spring	0.41 c	0.42 c	0.56 a	0.53 a	0.52 ab	0.48 b	0.41 c	0.47 A	0.03
	0.04	Winter	0.33 e	0.40 c	0.44 b	0.47 a	0.45 ab	0.41 c	0.36 d	0.41 B
S, (g 100 g plant ^−1 DW)	0.04	Spring	0.12 d	0.34 a	0.20 c	0.26 b	0.33 a	0.34 a	0.13 d	0.24 A	0.01
	0.02	Winter	0.14 c	0.24 a	0.19 b	0.20 b	0.23 a	0.23 a	0.16 c	0.20 B
Fe, (mg kg plant^−1 DW)	8.61	Spring	54 g	194 a	87 e	122 d	152 c	177 b	72 f	123 B	3.89
	13.1	Winter	63 g	221 a	108 e	139 d	164 c	209 b	85 f	141 A
Mn, (mg kg plant^−1 DW)	9.89	Spring	23 e	76 ab	50 c	70 b	81 a	81 a	35 d	59 A	2.79
	5.34	Winter	28 e	61 a	46 c	56 b	60 a	61 a	38 d	50 B
Zn, (mg kg plant^−1 DW)	4.73	Spring	27 d	40 b	36 c	43 b	42 b	47 a	34 c	38 A	1.60
	4.33	Winter	21 d	35 a	25 c	29 b	33 a	34 a	21 d	28 B
Cu, (mg kg plant^−1 DW)	2.73	Spring	6.53 e	14.00 a	7.10 de	9.13 bd	9.67 bc	11.00 b	7.57 c–e	9.29 A	0.73
	2.92	Winter	7.77 bc	9.90 ab	7.67 bc	7.00 c	8.23 bc	11.20 a	6.43 c	8.41 B
B, (mg kg plant^−1 DW)	4.22	Spring	12 d	30 a	19 c	22 bc	24 bc	25 b	13 d	19 A	1.26
	2.83	Winter	11 d	17 ab	14 c	17 ab	18 a	16 bc	11 d	15 B
Mo, (mg kg plant^−1 DW)	0.10	Spring	1.01 f	1.25 b	1.1 de	1.18 c	1.16 cd	1.33 a	1.05 ef	1.17 A	0.04
	0.07	Winter	0.65 d	0.86 a	0.75 c	0.79 bc	0.84 ab	0.85 a	0.63 d	0.77 B
Cd, (mg kg plant^−1 DW)	0.04	Spring	0.12 e	0.30 a	0.20 d	0.22 cd	0.24 bc	0.25 b	0.13 e	0.21 A	0.01
	0.03	Winter	0.10 g	0.29 a	0.14 e	0.17 d	0.19 c	0.24 b	0.12 f	0.18 B
^1:1=Nil, 2=SS, 3=75% SS+25% MF, 4=50% SS+50% MF, 5=25% SS+75% MF, 6=MF, 7=BM. LSD values (P<0.01) of spring and winter production: ^2,3 in groups LSDs and values followed by the in the lines are significantly different:^4,5 among groups LSDs and values followed by the different capital letter in the lines are significantly different. Italicized values are P<0.05, NS: not significant.