Energy efficiency in an integrated agro-ecosystem within an acidic soil area of the Mekong Delta, Vietnam

Table 2 Inputs and yields for system components according to the present farming household system (in a year)

Item	Unit	Equivalent factor (J_ex/Unit)	Reference	Pig production	Fish production	Orchard
Renewable resource (RR)
Sunlight^a	J	1.02E− 05	[11, 18, 21]	1.17E+ 08	3.26E+ 09	1.63E+ 09
Wind^b	J	3.12E− 02	[18, 21]	7.08E+ 08	1.97E+ 10	9.83E+ 09
Evapotranspiration^c	J	6.26E− 01	[11, 18]	1.11E+ 12	3.09E+ 11	1.55E+ 11
Natural non-renewable resources (NR)
Water	kg	4.94E− 03	[18, 37]		4.94E+ 08	3.84E+ 06
Ground water	m³	2.00E+ 04	[38]	1.34E+ 09
Loss of topsoil ^d	kg	4.33E+ 07	[5, 10]			2.06E+ 11
Purchased non-renewable resources (PN)
Diesel	L	4.78E+ 07	[38]	1.74E+ 10
Concrete	kg	6.35E+ 12	[12]	2.08E+ 11
Electricity	kW	3.60E+ 06	[18, 38]	5.18E+ 11
Weaned piglet	kg	2.09E+ 06	[39]	1.41E+ 11
Pig feed	kg	1.43E+ 07	[40]	3.32E+ 13
Lime (CaO)	kg	3.11E+ 06	[41]		3.04E+ 09	7.09E+ 09
Small fry	kg	7.98E+ 06	[42]		7.98E+ 10
Fish feed	kg	1.26E+ 07	[43]		128.E+ 14
Fertilizer
N	kg	3.28E+ 01	[9, 44]			1.28E+ 11
P		7.52E+ 01
K		4.56E+ 01
Pesticide	kg	4.20E+ 08	[18]			1.26E+ 09
Plough	kg	1.80E+ 08	[12]			2.47E+ 11
Sapling	kg	1.44E+ 07	[18]			9.45E+ 08
Yield (Y)
Porker	kg	2.03E+ 07	[45]			1.15E+ 13
Fish	kg	7.98E+ 06	[45]			7.98E+ 12
Fruit	kg	1.89E+ 12	[18]			2.48E+ 10

^aSolar energy = (the average radiation of province) × (area)
The average radiation of province = 17.5 MJ/(m² day) = 6,387.5 MJ/(m² year)
^bGlobal wind circulation = (0.4 J/m²/sec) × (3.15E+7 sec/year) × (area)
^cEvapotranspiration, chemical energy = (area) × (average rainfall) × (density) × (Gibbs free energy)
Average rainfall = 2 m/year
Density = 1.00E+ 06 g/m³
Gibbs free energy = 4.94 J/g
^dNet loss of topsoil = (soil loss) × (organic matter content) = 9.5 t/ha × 2.5 ha
Soil loss = 9.5 t/(ha year)
Organic matter content = 20% = 0.2

ISSN: 2192-0567