Fossil Fuel Use in Agriculture

Energy is required for all agricultural operations. Modern intensive agriculture requires much more energy input than did traditional farming methods, since it relies on the use of fossil fuels for tillage, transportation and grain drying, for the manufacture of fertilizers, pesticides and equipment used as agricultural inputs, and for generating electricity used on farms (Frye, 1984). Early estimates suggested that fossil fuel usage by agriculture, primarily of liquid fuels and electricity, constitute only 3-4% of the total consumption in developed countries (CAST, 1992; EnquĂȘte Commission, 1995). To provide a reference for agriculture's contribution, C emissions from fossil fuel use in the USA in 1996 were reported to be 286.7, 229.9, 477.5 and 445.5 MMTCE for residential, commercial, industrial and transportation sectors, respectively (EPA, 1998). The total amount of C emitted as CO2 in the USA in 1996 from

Table 3.1. Estimates of global carbon pools.

Total C content (MMTCE)a

Pool

Bouwman, 1990

Eswaran et al., 1993

Atmosphere

720,000

750,000

Biomass

560,000-835,000

550,000

Soil organic matter

1,400,000-2,070,000

1,500,000

Calicheb

780,000-930,000

-

Oceans

38,000,000

38,000,000

aMillion metric tonnes of carbon equivalent. bPetrocalcic horizons in arid and semi-arid regions.

aMillion metric tonnes of carbon equivalent. bPetrocalcic horizons in arid and semi-arid regions.

fossil fuels was 1450.3 MMTCE, a value that has steadily increased with time. Revised estimates by Lal et al. (1998) showed that US agriculture has contributed 116 of the total 1596 MMTCE (i.e. 7.3%) of US emissions. These agricultural emissions include an additional 15 MMTCE due to soil erosion (not included in earlier estimates) and 27.9 MMTCE due to direct on-farm energy use and indirect fertilizer and pesticide production.

Tillage and harvest operations account for the greatest proportion of fuel consumption within intensive agricultural systems (Frye, 1984). Fuel requirements using no-till or reduced tillage systems were 55 and 78%, respectively, of that used for conventional systems that included mouldboard ploughing. On an aerial basis, savings of 23 kg C ha-1 per year in energy costs resulted from the conversion of conventional till to no-till. For the 186 Mha of cropland in the USA, this translates into potential C savings of 4.3 MMTCE per year. Kern and Johnson (1993) calculated that conversion of 76% of the cropland planted in the USA to conservation tillage could sequester as much as 286-468 MMTCE over 30 years and concluded that US agriculture could become a net sink for C. Lal (1997) provided a global estimate for C sequestration from conversion of conventional tillage to conservation tillage that was as high as 4900 MMTCE by 2020. Combining economics of fuel cost reductions and environmental benefits of conversion to conservation tillage is a positive first step for agriculture toward decreasing C emissions into the atmosphere.

A summary of the fossil fuels used in US agriculture in 1996 is presented in Table 3.2. The three major fuels used released more than 19 MMTCE directly in 1995, with diesel fuel being the largest contributor. Nitrogen fertilizers, which require the greatest amount of energy to produce, are used in larger amounts than any other fertilizer. Net energy use in fertilizer manufacture has declined up to 40% recently, due to substantial improvements in plant efficiencies and use of natural gas. Estimates of energy required are 45.5, 10.8 and 5.0 Btu g-1 of product for N, P2O5 and K2O, respectively (Shapouri et al., 1995). For example, converting from Btu to joules (J) (1 Btu = 1055.06 J) and using the C content for natural gas (13.6 kg C 10-9 J) yields 0.66 tons of C released per ton of N produced. Therefore, the annual global consumption of about 80 Tg of fertilizer N corresponds to the consumption of about 53 MMTCE released as CO2. Fertilizer and chemical production in the USA has increased steadily since the 1940s, and contributed 8.3 MMTCE to the atmosphere in 1996. These combined estimates of fossil fuels used in US agriculture represent about 2% of the total US C emissions. However, this table does not include energy for electricity used for heating and cooling or energy for equipment manufacture. Pimentel and Heichel (1991) estimated that the energy required for making agricultural machinery is equal to the fuel used to grow the crop.

Pimentel (1984) indicated that 17% of the total energy used in the US economy is consumed in food systems, with about 6% for agricultural production, 6% for processing and packaging and 5% for distribution and preparation. This 17% of the total US energy use represents an annual per capita use of about 1500 litres of fuel just for food. Taking the C content of fuel oil as 0.73 kg C l-1 and multiplying by an estimated US population of 270 million in mid-1998 suggests that food production, processing and

Table 3.2. US agricultural emissions of carbon from use of fossil fuels directly in 1995 and indirectly for chemical inputs in 1996.

Fuelsa

Volume (106 l)

Carbon (MMTCE)

Diesel

13,626

11.02

Gasoline

5,626

3.32

Propane

3,028

4.97

Sum

19.31

Chemicalsb

Weight (kg x 106)

Carbonc

Nitrogen (N)

6,916.9

6.30

Phosphorus (P2O5)

2,904.0

0.61

Potash (K2O)

3,181.0

0.31

Herbicide

155.1

0.68

Insecticide

18.8

0.08

Fungicide

3.32

0.01

Other chemicals

59.1

0.26

Sum

8.25

aSource: Agricultural Resources and Environmental Indicators #16, Dec. 1996; USDA-ERS, Office of Energy, based on data gathered by NASS. b Source: USDA-NASS, Agricultural Statistics Board. 1996 Field Crops Summary, Agricultural Chemical Usage.

cAssuming fuel was natural gas at 14 mg C (Btu)-1. Represents 100% of land farmed (123,968,000 ha), which was extrapolated from a survey that covered seven major crops and 71.5% of land.

aSource: Agricultural Resources and Environmental Indicators #16, Dec. 1996; USDA-ERS, Office of Energy, based on data gathered by NASS. b Source: USDA-NASS, Agricultural Statistics Board. 1996 Field Crops Summary, Agricultural Chemical Usage.

cAssuming fuel was natural gas at 14 mg C (Btu)-1. Represents 100% of land farmed (123,968,000 ha), which was extrapolated from a survey that covered seven major crops and 71.5% of land.

preparation would emit about 296 MMTCE per year in the USA, or about 20% of the US total (Houghton et al, 1996). Fossil fuel requirements by the food sector as a whole (which includes processing, preservation, storage and distribution) account for 10-20% of the total fossil energy consumption (Pimentel et al., 1990; CAST, 1992). Thus, mitigation of energy use by agriculture should consider the 11% in non-production areas when considering solutions for decreasing the amount of CO2 emitted by agriculture.

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Responses

  • sirpa
    Did tradiitonal agriculture use fossil fuels?
    1 year ago
  • Tony
    Where is fuel power used in agriculture?
    1 year ago
  • Randy
    Which fossil fuels required for traditional agricultural practices?
    12 months ago
  • sara
    How does industrial agriculture use fossil fuels?
    9 months ago
  • adalberto
    What is fossil fuel used for on farms?
    8 months ago
  • mulu
    How are fossil fuels used in modern agriculture?
    7 months ago
  • rina
    How does modern agriculture affect the use of fossil fuels?
    7 months ago
  • merico
    How many fossil fuels does the agriculture industry use?
    5 months ago
  • Max
    How much fossil fuels are used in livestock farming?
    4 months ago
  • Shane
    How fossil fuels are used to produce fertilizers and pesticides?
    4 months ago
  • pandora
    Which is worse for climate fossil fuels or agriculture?
    2 months ago
  • Semhar
    How fossil fuels changed agriculture?
    1 month ago
  • lena
    Does fossil fuels the crops in detroit?
    1 month ago
  • klaudia
    What are some agricultures qatar uses fossil fuel for?
    23 days ago
  • REZENE
    Which aspect of modern farming tends to require the most fossilfuel derived energy?
    23 days ago
  • settimo
    How the fossil fuel is used in fertilizer?
    19 days ago

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