# Energy inputs in production agriculture: Life cycle analysis

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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)

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

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. Primary content is different from consumer content of energy, as it costs energy to transport fuel from oil field to the use point. Consumer content for diesel is about 35MJ/litre.

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

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. Total energy = (25x210)+(1x310)+(5x310) = 3963MJ/ha Total kg CO2 = 3963x0.06 = 238kg/ha CO2 compared to energy input: conversion factor of 0.06kg CO2 emission per MJ energy in chemical production

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 CO2 use per MJ energy in steel manufacture is higher than in agrochemicals

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. .095kg per MJ = kg/ha/yr Energy used in manufacture and maintenance of farm machinery Type Energy in materials MJ/kg Energy consumption for manufacture MJ/kg % energy consumption for repairs Total MJ/kg Powered 36 14 32% 66 Trailed 32 8 28% 51.2

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. .1 kg per MJ = 180.9kg/ha/yr Energy used in manufacture and maintenance of farm machinery Type Energy in materials MJ/kg Energy consumption for manufacture MJ/kg % energy consumption for repairs Total MJ/kg Powered 36 14 32% 66 Trailed 32 8 28% 51.2

Total energy and CO2: Orchard Case Study
Total energy and carbon dioxide for organic and conventional apple production in Ireland Item MJ/ha Organic MJ/ha Conventional Kg CO2/ha Organic Kg CO2/ha Conventional Fuel 18900 1050 Fertiliser 380 3800 20 200 Chemicals 1800 3963 95 238 Buildings 147.5 14.75 Tractor 1518 144.21 Farm equipment 1809 180.9 Total 24555 30138 1506 1818 Yields (kg/ha) 20000 50000 Energy/CO2 per kg fruit 1.2MJ/kg 0.6MJ/kg 75g CO2/kg 36gCO2/kg

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. 1800kg CO2 per ha inputs 9200kg CO2 sequesterisation

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 Packaging: O.5kg cardboard per kg fruit @8MJ/kg cardboard = 4MJ I have not mentioned Air Transport of foods. E.g. strawberries flown from USA to Ireland. 500MJ of food energy takes ~15,000MJ of air fuel alone. @30MJ/kg transported.

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 1 watt hour = 3600 joules 20kW x 3600 = 72MJ You have spent 18 times more energy just collecting the pizza than you will get by eating it. Assuming that 40MJ already went into producing your 4MJ Pizza, who is worse; the food industry or you?

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