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Published byAshley Morse Modified over 3 years ago

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Energy inputs in production agriculture: Life cycle analysis Fuel –(for tractors, powered implements, running irrigation etc.) Fertiliser Agrochemicals –(sprays mostly) Farm buildings –(energy and carbon invested in constructing them) Farm vehicles and machinery –(energy and carbon invested in manufacturing them) Irrigation –(energy and carbon invested in infrastructure)

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Sample crop: Apples Some crops are annual. –Conduct an annual life cycle analysis Some crops are perennial. –Take a longer term analysis

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Fuel use: Orchard case study Orchard tractor uses 10l diesel fuel per hour. In one season it operates for 45 hours for each ha it works on. This is equivalent to 450 litres per ha per year. At primary content of 42 MJ/litre of diesel this is MJ per ha per year. This is equivalent to about 1050 kg CO2 per ha per year emissions.

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Fertiliser use: Orchard Case Study Fertilisers, especially nitrogen, are very energy intensive to produce. An annual application of 50kg per ha N, 10kg per ha P, and 40kg per ha K would represent: –3800MJ/ha –200 kg CO2 per ha

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Agrochemical use: Orchard case study Fungicides –25kg a.i./ha/yr. –Embodied energy 210MJ/kg a.i. Insecticides –1kg a.i./ha/yr. –Embodied energy 310MJ/kg a.i. Herbicides –5kg a.i./ha/yr. –Embodied energy 310MJ/kg a.i. Total energy = –(25x210)+(1x310)+(5x310) = 3963MJ/ha Total kg CO2 = –3963x0.06 = 238kg/ha

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Farm buildings: Orchard Case Study For basic orchard production: –5m2 building per ha of orchard Machinery shed Storage of empty fruit bins Assumed to be a galvanised steel barn –590MJ/m2 in construction –Assumed to need replacement after 20 years Embodied energy: –590x5/20 = MJ/ha CO2 emitted: –147.5 x 0.1 = 14.75kg/ha

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Machinery & equipment: Orchard Case Study Tractor –1 tractor per 10 ha; typical weight 3500kg, depreciated over 15 years –= 23kg mass/ha/yr. Energy embodied in tractor: –23 x 66 = 1518MJ/ha/yr. per MJ –= kg/ha/yr Energy used in manufacture and maintenance of farm machinery TypeEnergy in materials MJ/kg Energy consumption for manufacture MJ/kg % energy consumption for repairs Total MJ/kg Powered361432%66 Trailed32828%51.2

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Machinery & equipment: Orchard Case Study Other machinery –Sprayer, mower, mulcher, fertiliser spreader, forklift etc. –Total weight 5300kg (for 10 ha, over 15 years) Energy embodied in machinery: –35.3 x 51.2 = 1809MJ/ha/yr. kg per MJ –= 180.9kg/ha/yr Energy used in manufacture and maintenance of farm machinery TypeEnergy in materials MJ/kg Energy consumption for manufacture MJ/kg % energy consumption for repairs Total MJ/kg Powered361432%66 Trailed32828%51.2

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Total energy and CO2: Orchard Case Study Total energy and carbon dioxide for organic and conventional apple production in Ireland ItemMJ/ha OrganicMJ/ha Conventional Kg CO2/ha Organic Kg CO2/ha Conventional Fuel Fertiliser Chemicals Buildings Tractor Farm equipment Total Yields (kg/ha) Energy/CO2 per kg fruit 1.2MJ/kg0.6MJ/kg75g CO2/kg36gCO2/kg

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Completing the life cycle: Orchard Case Study (conv.) Energy embodied in fruit eaten –2.5MJ per kg Carbon –Sequesterisation into orchard soil: 2000kg carbon/ha/yr. –In woody plant tissue: 500kg carbon/ha/yr. –Also in fruit, approx kg carbon/ha/yr. CO2 equivalent –2500 /12*44 = ~ 9200 kg/ha/yr. Five times more CO2 taken from air than released in a single growing cycle.

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Life cycle beyond the orchard: Cold storage: –Average storage period = 6 months. –1-2MJ/kg (operating) Transport: –By ship from New Zealand 2MJ/kg –By road from Italy to Ireland 2MJ/kg Packaging: –O.5kg cardboard per kg fruit cardboard = 4MJ

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Life cycle beyond the orchard: Transport from shop to home: –A car using 10l/100km uses about 1kW power per km travelled A 3 mile trip to the shop and back (6 miles or 10km total) : –10kW Assume you collect 10kg of groceries, 1kg of which is a bag of apples –Then 1 kg of apples required 1kW to collect. –Equivalent to 3.6MJ per kg collected Question: –What about if you drive 6 miles to town for a take-away Pizza? Goodfellas 400g ~ 4MJ Remember 1 watt hour = 3600 joules

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