Socio-economic impacts of possible brewery waste recycling in agriculture

Figures & data

Figure 1. The geological structure of the experimental areas

Table 3. Maize, sorghum and khat crop yield of sampled households

Variables	Before application of BS		After application of BS		t test
	Mean	SD	Mean	SD
Maize	20	6.66	30	9.02	0.000
Sorghum	14	4.88	22	4.51	0.001
Total crop yield	37	12.83	63	30.65	0.000
Khat	70		180		0.000
Total	141		295

Where; BS = Brewery sludge, and SD = Standard deviation. Sources: survey result, 2012/2013

Table 1. Summary descriptive results of continuous variables

Variable	Mean	SD	Min	Max
Age	40	14.18	20	70
Family size	8.15	5.43	4	25

Where; BS = Brewery sludge, SD = Standard deviation, Min = Minimum age, and Max = Maximum age. Sources: survey result, 2012/2013.

Table 2. Farmer’s perception on the brewery sludge use for crop production and soil fertility

	Activities	Variables	Share (%)
Time of brewery sludge application	Before sowing	7	58.33
	During sowing	2	16.66
	After sowing	2	16.66
Crop types cultivated by brewery sludge use	Maize and sorghum	4	33.33
	Khat	2	16.66
	Maize, sorghum and khat	6	50
Land management inputs	Brewery sludge	5	41.66
	Fertilizer	5	41.66
	Both	2	16.66
Trends of sampled farmers crop yield	Increasing	10	83.33
	Decreasing	2	16.66
Overall trends of sampled farmers crop productivity	Increasing	7	83.33
	Decreasing	2	16.66
Application of brewery sludge for soil fertility	Yes	7	83.33
	No	2	16.66

Table 4. Estimated sample households incomes from maize and sorghum crops per hectare in USD

Sources	Before BS application		After BS application		Mean difference
	Mean	SD	Mean	SD
Maize	471.20	152.63	686.81	206.40	215.61
Sorghum	333.84	111.93	503.66	103.31	169.83

Where; BS = Brewery sludge, SD = Standard deviation and USD = United States Dollars. Sources: survey result, 2012/2013.

Table 5. Impacts of different rates of brewery sludge on maize and sorghum yield

BS rate ha^−1	Maize yield(t ha^−1)	Sorghum yield(t ha^−1)	Percentage of Nitrogen contents
			Maize	Sorghum
2.5	3.16	2.01	1.21	1.39
5.0	4.13	2.99	1.32	1.46
7.5	4.31	3.08	1.33	1.55
10.0	4.35	3.28	1.40	1.61
12.5	4.37	3.13	1.44	1.54
15.0	5.19	4.08	1.33	0.61
NP	2.04	1.77	1.29	1.36
Control	0.77	0.86	1.55	1.45

Where; BS = Brewery sludge, NP = Recommended rate of inorganic nitrogen and phosphorus fertilizer, and t ha⁻¹ = Total yield per hectare.

Table 6. Impacts of different rates of sludge on potato and haricot bean yield

BS rate (t ha^−1)	Potato yield (t ha^−1)	Haricot bean yield(t ha^−1)	Nitrogen contents
			In Haricot bean
2.5	14.59	3.39	2.95
5	14.77	4.90	3.22
7.5	19.59	4.90	3.13
10	20.39	4.94	3.37
12.5	28.24	5.96	3.15
15	25.02	5.99	3.08
NP	9.52	2.82	2.82
Control	7.59	1.84	2.91

Where; BS = Brewery sludge, and t ha⁻¹ = Total yield per hectare.

Table 7. Partial budget analysis for different rates of brewery sludge and NP fertilizers in maize production

BS rate(t ha^−1)	Average yield (t ha^−1)	Adjusted yield (t ha^−1)	GFB (0.18 USD kg^−1)	Costs of BS application	Cost of NP	BS TP cost	Total cost that vary	Net benefit	Domain
0	0.77	0.73	134.34	0.00	0.00	0.00	0.00	134.34	ND
2.5	3.16	2.84	520.86	7.79	0.00	28.14	35.93	484.93	ND
NP	2.04	1.94	354.49	6.87	63.19	0.00	70.05	284.44	D
5	4.13	3.72	681.49	15.58	0.00	56.28	71.85	609.64	ND
7.5	4.31	3.88	710.36	23.36	0.00	84.42	107.78	602.57	D
10	4.35	3.92	717.64	31.15	0.00	112.56	143.71	573.93	D
12.5	4.37	3.93	720.16	38.94	0.00	140.70	179.64	540.52	D
15	5.19	4.67	856.14	46.73	0.00	168.84	215.57	640.57	ND

Where; MRR = Marginal rate of return, GFB = gross field benefit, TP = transportation, ND = Non-Dominated, D = Dominated, BS = Brewery sludge, USD = United States Dollars, and average exchange rate in 2012/2013 of one dollar was 21.84 ETB (Ethiopian Birr).

Table 8. Marginal rate of return analysis of brewery sludge for maize production

BS rate(t ha^−1)	Average yield(t ha^−1)	Adjusted yield(kg ha^−1)	GFB (`0.18 USD kg^−1)	Total cost that vary	Net benefit	MRR (%)
0.0	0.77	0.73	134.34	0.00	134.34	-
2.5	3.16	2.84	520.86	35.93	484.93	975.84
5	4.13	3.72	681.49	71.85	609.64	347.1
15	5.19	4.67	856.14	215.57	640.57	21.52

Where; MRR = Marginal rate of return, GFB = gross field benefit, USD = United States Dollars, and average exchange rate in 2012/2013 of one dollar was 21.84 ETB (Ethiopian Birr).

Table 9. Partial budget analysis for brewery sludge and NP fertilizers for sorghum production

BS rate(t ha^−1)	Average yield (t ha^−1)	Adjusted yield (t ha^−1)	GFB (0.23 USD kg^−1)	Costs of BS application	Cost NP	BS TP cost	Total cost that vary	Net benefit	Domain
0.0	0.86	0.82	0.00	0.00	0.00	0.00	0.00	186.61	ND
2.5	2.01	1.81	414.97	7.79	0.00	28.14	35.93	379.04	ND
NP	1.77	1.68	384.52	6.89	63.19	0.00	70.05	314.47	D
5	2.99	2.69	616.69	15.58	0.00	56.28	71.85	544.83	ND
7.5	3.08	2.77	634.20	23.36	0.00	84.42	107.78	526.42	D
10	3.28	2.95	676.24	31.15	0.00	112.56	143.71	532.52	D
12.5	3.13	2.82	644.71	38.94	0.00	140.70	179.64	465.07	D
15	4.08	3.67	840.87	46.72894	0.00	168.84	215.57	625.30	ND

Where; MRR = Marginal rate of return, GFB = gross field benefit, TP = transportation, ND = Non-Dominated, D = Dominated, BS = Brewery sludge, USD = United States Dollars, and average exchange rate in 2012/2013 of one dollar was 21.84 ETB (Ethiopian Birr).

Table 10. Marginal rate of return analysis of brewery sludge for sorghum production

BS rate(t ha^−1)	Average yield(t ha^−1)	Adjusted yield(kg ha^−1)	GFB (0.23 USD kg^−1)	Total cost that vary	Net benefit	MRR (%)
0.0	0.86	0.82	186.61	0.00	186.61	-
2.5	2.01	1.81	414.97	35.93	379.04	535.62
5	2.99	2.69	616.69	71.85	544.83	461.46
15	4.08	3.67	840.87	215.57	625.30	71.48

Where; MRR = marginal rate of return, GFB = gross field benefit, BS = Brewery sludge, USD = United States Dollars, and Average exchange rate in 2012/2013 of one dollar was 21.84 ETB (Ethiopian Birr).

Table 11. Partial budget analysis for brewery sludge and NP fertilizers application in potato production

BS rate(t ha^−1)	Average yield (t ha^−1)	Adjusted yield (t ha^−1)	GFB (0.16 USD kg^−1)	Costs of Sludge application	Cost of NP	Sludge TP cost	Total cost that vary	Net benefit	Domain
0	7.59	7.21	1,155.68	0.00	0.00	0.00	0.00	1,155.68	ND
2	14.59	13.13	2,104.62	4.58	0.00	22.51	27.09	2,077.52	ND
4	14.77	13.29	2,130.29	9.16	0.00	45.02	54.18	2,076.11	D
NP	9.52	9.04	1,448.60	6.87	63.19	0.00	70.05	1,378.54	D
6	19.59	17.63	2,825.77	13.74	0.00	67.54	81.27	2,744.50	ND
8	20.39	18.35	2,940.14	18.32	0.00	90.05	108.36	2,831.78	ND
10	28.24	25.42	4,073.65	22.89	0.00	112.56	135.45	3,938.20	ND
12	25.02	22.51	3,607.93	27.47	0.00	135.07	162.55	3,445.39	D

Where; MRR = Marginal rate of return, GFB = gross field benefit, ND = Non-Dominated, D = Dominated, BS = Brewery sludge, USD = United States Dollars, and average exchange rate in 2012/2013 of one dollar was 21.84 ETB (Ethiopian Birr).

Table 12. Marginal rate of return analysis of brewery sludge for potato production

BS rate(t ha^−1)	Average yield(t ha^−1)	Adjusted yield(t ha^−1)	GFB (0.16 USD kg^−1)	Total cost that vary	Net benefit	MRR (%)
0.0	7.59	7.21	1,155.68	0.00	1,155.68	-
2	14.59	13.13	2,104.62	27.09	2,077.52	3,402.57
6	19.59	17.63	2,825.77	81.27	2,744.50	1,231.02
8	20.39	18.35	2,940.14	108.36	2,831.78	322.18
10	28.24	25.42	4,073.65	135.45	3,938.20	4,083.85

Where; MRR = Marginal rate of return, GFB = gross field benefit, BS = Brewery sludge, USD = United States Dollars, and average exchange rate in 2012/2013 of one dollar was 21.84 ETB (Ethiopian Birr).

Table 13. Partial budget analysis for brewery sludge and NP fertilizers in haricot bean production

BS rate(t ha^−1)	Average yield (t ha^−1)	Adjusted yield (t ha^−1)	Gross field return (0.23 USD kg^−1)	Costs of Sludge application	Cost of NP	BS TP cost	Total cost that vary	Net benefit	Domain
0	1.84	1.75	400.66	0.00	0.00	0.00	0.00	400.66	ND
2	3.39	3.05	698.88	4.58	0.00	22.51	27.09	671.79	ND
4	4.91	4.42	1,012.38	9.16	0.00	45.02	54.18	958.20	ND
NP	2.82	2.67	612.35	6.87	63.19	0.00	70.05	542.29	D
6	4.90	4.41	1,008.69	13.74	0.00	67.54	81.27	927.42	D
8	4.94	4.44	1,016.99	18.32	0.00	90.05	108.36	908.63	D
10	5.96	5.36	1,227.38	22.89	0.00	112.56	135.45	1,091.93	ND
12	5.99	5.39	1,233.59	27.47	0.00	135.07	162.55	1,071.04	D

Where; MRR = Marginal rate of return, TP = transportation, ND = Non-Dominated, D = Dominated, BS = Brewery sludge, USD = United States Dollars, and average exchange rate in 2012/2013 of one dollar was 21.84 ETB (Ethiopian Birr).

Table 14. Marginal rate of return analysis of brewery sludge levels for haricot bean production

BS rate(t ha^−1)	Average yield(t ha^−1)	Adjusted yield(t ha^−1)	GFB (0.23 USD kg^−1)	Total cost that vary	Net benefit	MRR (%)
0.0	1.84	1.75	400.66	0.00	400.66	-
2	3.39	3.05	698.88	27.09	671.79	1,000.74
4	4.91	4.42	1,012.38	54.18	958.20	1,057.15
10	5.96	5.36	1,227.38	135.45	1,091.93	164.55

Where; MRR = marginal rate of return, GFB = gross field benefit, BS = Brewery sludge, USD = United States Dollars, and average exchange rate in 2012/2013 of one dollar was 21.84 ETB (Ethiopian Birr).