Cultivation:

The intensive cultivation of corn (Zea Mais L.; maize) for exclusive corn use is modelled, assuming a 20 ha plot of land. Typical crop rotation 1:1 with soy beans. Harvest by combining. Seeding in late spring, usually no catch crop is cultivated. The most significant parameters and harvests are described in the attached table and the flow chart.

Corn, known among scientists as maize, is one of world's most important crops. Corn was a $47 billion crop in the United States last year. It is the largest production crop worldwide, providing food for billions of people and livestock and also feedstock for production of bio fuels. (O`BRIEN 2009). Table 1 shows the inventory data for the cultivation process and the main product characteristics. Stover was assumed to be left on the field, the nutritional value was considered as a credit for the following crop.
It was assumed that the corn is in a 80% crop rotation with the winter crop soy bean. 17% of the total area is fertilized by the use of liquid manure. The total amount of nitrogen applied with the manure is 160 kg N per hectare, this is equivalent to 6800 kg of manure per hectare with a nitrogen content of 0,4% N.
Tab. 1: Life cycle inventory data agricultural production - cultivation and main product characteristic
Parameter Value Unit Source
Cropping cycles per year 1 one per year USDA
Yield 10872 kg / year USDA
Seed input 35 kg/ha USDA
Product characteristics
Dry weight content 25 % USDA
Fertilizer application
N 147 kg/(ha*year) Seungdo K. et.al. 2009
P 61 kg/(ha*year) Seungdo K. et.al. 2009
K 76 kg/(ha*year) Seungdo K. et.al. 2009
Diesel cultivation process 2021 MJ/(ha*year) Seungdo K. et.al. 2009
Herbicide 2,03 kg AI / (ha*year) Seungdo K. et.al. 2009
Insectides 0,07 kg AI / (ha*year) Seungdo K. et.al. 2009
It is assumed that only mineral fertilizers are applied on the field, the diesel consumption for the irrigation pumps is calculated based on the water requirements. The ration between stover and grains in assumed as 1:1. 46% of the stover is removed from the soil (Source Seungdo K. et.al. 2009)

Background system:
Electricity: Electricity is modelled according to the individual country-specific situations. The country-specific modelling is achieved on multiple levels. Firstly, individual energy carrier specific power plants and plants for renewable energy sources are modelled according to the current national electricity grid mix. Modelling the electricity consumption mix includes transmission / distribution losses and the own use by energy producers (own consumption of power plants and "other" own consumption e.g. due to pumped storage hydro power etc.), as well as imported electricity. Secondly, the national emission and efficiency standards of the power plants are modelled as well as the share of electricity plants and combined heat and power plants (CHP). Thirdly, the country-specific energy carrier supply (share of imports and / or domestic supply) including the country-specific energy carrier properties (e.g. element and energy content) are accounted for. Fourthly, the exploration, mining/production, processing and transport processes of the energy carrier supply chains are modelled according to the specific situation of each electricity producing country. The different production and processing techniques (emissions and efficiencies) in the different energy producing countries are considered, e.g. different crude oil production technologies or different flaring rates at the oil platforms.
Thermal energy, process steam: The thermal energy and process steam supply is modelled according to the individual country-specific situation with regard to emission standards and considered energy carriers. The thermal energy and process steam are produced at heat plants. Efficiencies for thermal energy production are by definition 100% in relation to the corresponding energy carrier input. For process steam the efficiency ranges from 85%, 90% to 95%. The energy carriers used for the generation of thermal energy and process steam are modelled according to the specific import situation (see electricity above).
Transports: All relevant and known transport processes are included. Ocean-going and inland ship transport as well as rail, truck and pipeline transport of bulk commodities are considered.
Energy carriers: The energy carriers are modelled according to the specific supply situation (see electricity above).
Refinery products: Diesel fuel, gasoline, technical gases, fuel oils, lubricants and residues such as bitumen are modelled with a parameterised country-specific refinery model. The refinery model represents the current national standard in refining techniques (e.g. emission level, internal energy consumption, etc.) as well as the individual country-specific product output spectrum, which can be quite different from country to country. The supply of crude oil is modelled, again, according to the country-specific situation with the respective properties of the resources.