Assessing the Industrial Effluent Effect on Irrigation Water Quality and Farm Soil near Kombolcha Town, Ethiopia

Table 5

Independent sample t-test for the upstream and downstream Borkena irrigation water.

Parameter	Unit	Upstream irrigation water	Downstream irrigation water	Levene’s test for the equality of variance			t-test for the equality of means
				Assumption of variance	F	Sig.	t	df	Sig. (two-tailed)	Mean difference	95% confidence interval of difference
											Lower	Upper
EC	ds/m	0.48	0.96	Equal	7.08	0.76	−2.99	3	0.058	−2.00333	−4.1327	0.1261
				Unequal			−3.86	2	0.061	−2.00333	−4.2333	0.2266
Mg^+2	mg/l	2.18	5.27	Equal	9.6	0.53	−4.46	3	0.021	−4.70333	−8.0586	−1.3480
				Unequal			−5.76	2	0.029	−4.70333	−8.2172	−1.1895
Ca^+2	mg/l	10.00	16.61	Equal	6.11	0.90	−1.55	3	0.220	−8.26667	−25.2833	8.7499
				Unequal			−1.99	2	0.184	−8.26667	−26.0874	9.5540
Na^+	mg/l	1.46	3.35	Equal	3.34	0.17	−5.37	3	0.013	−26.1400	−41.6292	−10.6509
				Unequal			−6.93	2	0.020	−26.1400	−42.3610	−9.9189
Cl^-	mg/l	5.07	7.67	Equal	3.29	0.17	−3.58	3	0.057	−92.3366	−174.52	−10.1548
				Unequal			−4.62	2	0.044	−92.3366	−178.41	−6.2717
pH	-	8.38	8.54	Equal	5.66	0.98	−3.04	3	0.056	−0.55000	−1.1257	0.0257
				Unequal			−3.93	2	0.059	−0.55000	−1.1529	0.0529
CO3^−2	me/L	0.16	1.25	Equal	8.57	0.61	−3.35	3	0.054	−1.09000	−2.1239	−0.0561
				Unequal			−4.33	2	0.049	−1.09000	−2.1728	−0.0072
HCO3^-	me/L	4.76	9.10	Equal	3.97	0.14	−5.17	3	0.054	−15.5800	−25.170	−5.9895
				Unequal			−6.67	2	0.022	−15.5800	−25.6237	−5.5363
Fe	mg/l	0.05	4.25	Equal	2.73	0.19	−1.38	3	0.260	−3.31333	−10.92	4.2943
				Unequal			−1.79	2	0.215	−3.31333	−11.92	4.6537
Mn	mg/l	< L.D	0.18	Equal	9.60	0.05	−1.55	3	0.219	−0.01333	−0.0407	0.0140
				Unequal			−2.00	2	0.184	−0.01333	−0.4202	0.0153
Pb	mg/l	< L.D	0.47	Equal	6.54	0.08	−4.61	3	0.019	−0.7733	−1.307	−0.2396
				Unequal			−5.95	2	0.027	−0.7733	−1.3323	−0.2144
Cu	mg/l	0.06	0.21	Equal	3.94	0.14	−6.86	3	0.006	−0.20667	−0.3025	−0.1108
				Unequal			−8.86	2	0.013	−0.20667	−0.3071	−0.1063
Cr	mg/l	< L.D	0.31	Equal	3.57	0.16	−1.42	3	0.250	−0.0266	−0.0864	0.0330
				Unequal			−1.83	2	0.208	−0.0266	−0.0891	0.0358
Cd	mg/l	< L.D	0.03	Equal	9.60	0.05	−2.32	3	0.103	−0.0300	−0.0711	0.0111
				Unequal			−3.00	2	0.095	−0.0300	−0.073	0.1303
TDS	mg/l	305.07	612.98	Equal	7.08	0.08	−2.99	3	0.058	1282.13	−2644.92	80.652
				Unequal			−3.86	2	0.061	1282.13	−2709.31	145.845

Ca⁺: calcium; Cd: cadmium; Cl⁻: chloride; CO₃⁻²: carbonate; Cr: chromium; Cu: copper;EC: electrical conductivity; Fe: iron; HCO₃⁻: bicarbonate; Mg⁺²: magnesium; Mn: manganese; Na⁺: sodium; Ni: nickel; Pb: lead; SAR: specific absorption rate; TDS: total dissolved solids; < L.D: less than the limit of detection; F: statistics computed from sample variance for Levene’s test; Sig.: significance; t: value of t-test (single value obtained after reduction of the entire sample by the t-test procedure); df: degree of freedom; Sig. (two-tailed): significance for two-tailed test.