Risk assessment of irrigated lacustrine & calcareous soils by treated wastewater

Peer review under responsibility of National Water Research Center.

Figures & data

Table 1 The main chemical and physical characteristics of the soils under study.

Soil parameter	Lacustrine soil	Calcareous soil
pH	8.0	8.2
ECe (dS m^−1)	0.7	3.3
Total CO3 (%)	3.65	28.4
O.M. (%)	2.18	0.90
Available N (mg kg^−1 soil)	65	50
Available P (mg kg^−1 soil)	8.5	4.8
Available K (mg kg^−1 soil)	460	200
Particle size distribution
Sand (%)	57	79
Silt (%)	20	9
Clay (%)	23	12
Soil texture	Sandy clay loam	Sandy loam
Field capacity (%)	56	45.0
Bulk density (g cm^−3)	1.74	1.65

Table 2 Some water quality parameters of irrigation water.

Parameter	FW	TWW	1:1 FW/TWW	Limits
pH	7.95	8.1	7.45	6.5–8.5^a
TDS (mg l^−1)	665	2300	1525	450–2000^a
SAR	3.65	8.85	7.7	Linked to TDS^a
Total N (mg l^−1)	13.10	38.5	29.5	–
NO3 (mg l^−1)	2.06	6.33	3.43	0–30^b
Total P (mg l^−1)	1.95	12	8.4	0–15^b
Total K (mg l^−1)	170	335	230	–
COD (mg l^−1)	33.5	210	92.5	50^c
BOD5 (mg l^−1)	7.25	77.5	31.5	30^c
FC (cfu/100 ml)	10	470	220	0–1000^b

Sodium adsorption ratio: SAR = [Na²⁺]/([Ca²⁺] + [Mg²⁺])^1/2.

n = 12.

a FAO (Ayers and Westcot, 1989).

b World Health Organization (Cairncross and Mara, 1989).

c Egyptian Ministerial Decree No. 92 of 2013 amending the Ministerial Decree No. 8 of 1982 on the executive Regulations of Law No. 48 of 1982 concerning the Protection of the Nile River and water channels from pollution.

Table 3 Some chemical and biological characteristics of lacustrine soil cultivated with soybean, corn, faba bean or wheat as influenced by treatment wastewater (TWW), fresh water (FW) and mix of TWW and FW in equal proportions (mixed water).

Water of irrigation	Soil depth	pH	ECe (dS m^−1)	SAR	OM (%)	Coliform (MPN/100 g)		Available (mg/kg^−1)
						TC	FC	N	P	K
Soybean soil
FW	0–20	7.22	0.66	1.29	2.10	4 × 10^3	400	96	7.85	440
	20–40	7.12	0.70	1.32	2.00	5 × 10^2	200	90	8.00	485
TWW	0–20	7.54	1.36	4.70	2.70	7 × 10^7	3000	114	9.50	780
	20–40	7.35	1.88	4.80	2.40	5 × 10^3	1200	120	8.80	790
1:1 FW/TWW	0–20	7.20	0.70	1.43	2.32	3 × 10^6	2300	110	7.83	488
	20–40	7.15	0.78	1.50	2.20	4 × 10^3	1000	110	7.70	560
LSD 0.05		0.17	0.04	0.60	0.06	–	260	13	0.74	85
Corn soil
FW	0–20	7.15	0.73	1.33	2.10	5 × 10^3	450	85	7.90	550
	20–40	7.40	0.80	1.45	2.00	4 × 10^2	250	84	7.70	665
TWW	0–20	7.40	0.93	1.77	2.55	5 × 10^7	3300	105	9.35	780
	20–40	7.80	0.97	1.95	2.30	3 × 10^3	1300	104	8.50	880
1:1 FW/TWW	0–20	7.00	0.80	1.74	2.16	3 × 10^6	2600	100	7.80	730
	20–40	7.20	0.90	2.00	2.04	3 × 10^2	1200	100	7.80	870
LSD 0.05		0.20	0.03	0.95	0.09	–	290	14	0.72	125
Faba bean soil
FW	0–20	7.11	0.68	1.06	2.19	5 × 10^3	500	88	8.80	475
	20–40	7.25	0.75	1.25	1.95	3 × 10^2	250	89	8.25	530
TWW	0–20	7.24	1.35	3.58	2.89	5 × 10^7	3400	110	11.35	700
	20–40	7.20	1.45	4.10	2.30	5 × 10^3	1400	112	9.60	890
1:1 FW/TWW	0–20	7.23	1.30	3.27	2.35	2 × 10^6	2900	110	7.73	560
	20–40	7.30	1.45	4.00	2.08	5 × 10^3	1300	110	7.90	700
LSD 0.05		0.17	0.13	0.85	0.06	–	290	19	0.77	135
Wheat soil
FW	0–20	7.25	0.70	1.21	2.00	5 × 10^3	500	86	8.15	480
	20–40	7.15	0.85	2.00	1.98	3 × 10^2	250	91	8.00	590
TWW	0–20	7.35	1.45	4.57	2.40	5 × 10^7	3400	108	10.00	790
	20–40	7.15	1.95	5.10	2.10	5 × 10^3	1400	110	9.15	820
1:1 FW/TWW	0–20	7.30	1.25	4.00	2.15	2 × 10^6	2900	110	8.23	615
	20–40	7.40	1.45	5.00	2.02	5 × 10^3	1300	115	8.00	780
LSD 0.05		0.14	0.18	1.40	0.07	–	290	13	0.75	140

Table 4 Some chemical and biological characteristics of calcareous soil cultivated with soybean, corn, faba bean or wheat as influenced by treatment wastewater (TWW), fresh water (FW) and mix of TWW and FW in equal proportions (mixed water).

Water of irrigation	Soil depth	pH	ECe (dS m^−1)	SAR	OM (%)	Coliform (MPN/100 g)		Available (mg/kg^−1)
						TC	FC	N	P	K
Soybean soil
FW	0–20	8.11	3.15	4.80	0.84	8 × 10^2	200	70	3.90	340
	20–40	8.10	3.55	4.95	0.80	0	60	74	3.60	480
TWW	0–20	8.25	3.65	5.60	1.45	5 × 10^4	2000	98	6.25	630
	20–40	8.10	4.00	5.80	1.20	8 × 10^2	300	100	5.50	750
1:1 FW/TWW	0–20	8.11	3.20	5.10	1.00	4 × 10^3	1000	85	4.67	475
	20–40	8.16	3.68	5.50	0.93	4 × 10^2	180	84	4.50	650
LSD 0.05		0.22	0.14	0.85	0.07	–	80	12	0.77	38
Corn soil
FW	0–20	8.10	2.95	5.20	0.92	4 × 10^2	200	75	3.75	280
	20–40	8.00	3.10	6.00	0.80	0	60	76	3.30	340
TWW	0–20	8.20	3.60	5.54	1.35	6 × 10^4	2100	95	5.75	500
	20–40	8.10	4.10	6.40	1.10	4 × 10^2	300	92	5.25	620
1:1 FW/TWW	0–20	8.00	3.00	5.71	1.15	5 × 10^3	1100	86	4.45	450
	20–40	8.15	3.50	6.55	0.98	3 × 10^2	170	84	3.80	560
LSD 0.05		0.19	0.14	1.00	0.08	–	90	13	0.42	44
Faba bean soil
FW	0–20	7.95	3.10	4.95	0.95	6 × 10^2	240	80	3.56	300
	20–40	8.00	3.30	5.50	0.90	0	60	84	3.50	330
TWW	0–20	8.15	5.85	6.75	1.55	1 × 10^5	2100	125	6.50	620
	20–40	8.00	6.95	7.00	1.25	4 × 10^2	300	120	5.00	700
1:1 FW/TWW	0–20	8.05	4.64	5.81	0.98	5 × 10^4	1100	95	4.85	460
	20–40	8.00	5.00	6.50	0.92	4 × 10^2	180	92	4.30	520
LSD 0.05		0.23	0.17	0.85	0.08	–	90	12	0.67	58
Wheat soil
FW	0–20	7.95	3.50	4.56	0.94	5 × 10^2	260	79	3.90	400
	20–40	8.00	3.65	5.10	0.90	0	60	85	3.50	460
TWW	0–20	8.15	6.80	6.63	1.40	7 × 10^5	2200	115	5.85	600
	20–40	8.00	7.00	7.25	1.18	4 × 10^2	300	110	5.10	680
1:1 FW/TWW	0–20	8.25	5.16	6.13	1.10	3 × 10^4	1200	95	5.50	560
	20–40	8.30	5.65	7.00	1.00	5 × 10^2	170	96	5.40	660
LSD 0.05		0.23	0.13	0.75	0.08	–	90	16	0.69	48

Fig. 1 Relative increase (%) in soil salinity of lacustrine cultivated soils as influenced by TWW and 1:1 FW/TWW irrigation treatments.

Fig. 2 Relative increase (%) in soil salinity of calcareous cultivated soils as influenced by TWW and 1:1 FW/TWW irrigation treatments.

Fig. 3 Relative increase (%) in FC of lacustrine cultivated soils as influenced by TWW and 1:1 FW/TWW irrigation treatments.

Fig. 4 Relative increase (%) in FC of calcareous cultivated soils as influenced by TWW and 1:1 FW/TWW irrigation treatments.

Fig. 5 The effect of irrigation water treatments, soil type on plant dry weight (A), leaf N-content (B), leaf P-content (C) and leaf K-content (D).

Fig. 6 The effect of irrigation water treatments and soil type on TDS (A) and FC (B) in drainage water.