# Environmental Impact of Corn Tortilla Production: A Case Study
## 2 Materials and Methods
### Corn Production  
In order to carry out the LCI of corn production, a producer from the city of Quiroga, Michoacan, Mexico, was interviewed. The resulting information is detailed below. * Preparation of the land. There are two annual sowing seasons. The producer performs rotary sowing by conservation mode with a plough or fallow stage, two narrowing steps, and then sowing. For these activities, he uses a New Holland 6610 tractor which, according to [PERSON] et al. (2013), has a power of 88 hp, 77 hp to the power take-off (PTO) and a fuel consumption of 7.5 L for each hour of work. * Sowing. A two-row planter with a cultivator is used to sow the seed and perform the first fertilisation. The farmer requires 30 kg of seeds for each hectare planted and it takes approximately 2 h to carry out the activity. * Fertilisation. The amount of fertiliser was calculated by considering the doses shown in Table 3. The production is carried out by means of seeding by storm, in common with the majority of the country ([PERSON], 2013), adding 40% of the nitrogen in the first fertilisation at the time of sowing and the remaining 60% in the second. The producer mentioned that the fertilisers he uses are diammonium phosphate (DAP) and urea with NPK contents of 18-46-0 and 46-0-0, respectively. Water consumption is assigned according to the green water footprint reported by [PERSON] and [PERSON] (2013) for Mexico in corn crops. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Raw Material**} & **Mass** & **Distance** & **Quantity** \\ \cline{2-4}  & **(kg)** & **(km)** & **kg-km** \\ \hline Corn seeds & \(7.83\times 10^{-3}\) & 0 & 0 \\ \hline Fertiliser 1 & & \(8.68\times 10^{1}\) & \(2.71\times 10^{0}\) \\ DAP (diammonium phosphate) & \(3.13\times 10^{-2}\) & \(1.13\times 10^{2}\) & \(3.53\times 10^{0}\) \\  & & \(4.85\times 10^{1}\) & \(1.52\times 10^{0}\) \\ \hline Fertiliser 2 & & \(8.68\times 10^{1}\) & \(9.55\times 10^{0}\) \\ Urea & \(1.10\times 10^{-1}\) & \(1.13\times 10^{2}\) & \(1.24\times 10^{1}\) \\  & & \(4.85\times 10^{1}\) & \(5.34\times 10^{0}\) \\ \hline Herbicide 1 & & \(3.17\times 10^{2}\) & \(2.19\times 10^{-1}\) \\ Desyerbal-500 & \(6.91\times 10^{-4}\) & \(4.45\times 10^{1}\) & \(3.07\times 10^{-2}\) \\ \hline Herbicide 2 & & \(3.17\times 10^{2}\) & \(1.47\times 10^{-1}\) \\ Machetazo 2000 & & \(4.45\times 10^{1}\) & \(2.07\times 10^{-2}\) \\ \hline Pesticide 1 & \(1.88\times 10^{-5}\) & \(3.17\times 10^{2}\) & \(5.94\times 10^{-3}\) \\ Cypermethrin 200 & & \(4.45\times 10^{1}\) & \(8.34\times 10^{-4}\) \\ \hline Pesticide 2 & & \(3.17\times 10^{2}\) & \(3.31\times 10^{-2}\) \\ Analor-480 & \(1.04\times 10^{-4}\) & \(4.45\times 10^{1}\) & \(4.64\times 10^{-3}\) \\ \hline Corn & \(7.10\times 10^{-1}\) & \(9.38\times 10^{2}\) & \(6.66\times 10^{2}\) \\ \hline Quicklime & \(1.06\times 10^{-2}\) & \(2.54\times 10^{2}\) & \(2.70\times 10^{0}\) \\  & & \(4.88\times 10^{1}\) & \(5.20\times 10^{-1}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Life cycle inventory of the transport of materials for corn production. \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{**Humidity Condition**} & **NPK Fertilisation Dose (kg ha\({}^{-1}\))** \\ \hline Irrigation & 250-46-00 \\ Watering tip & 230-46-00 \\ Efficient temporary (greater than 650 mm of annual precipitation) & 184-46-00 \\ Poor temporary (less than 650 mm of annual precipitation) & 138-46-00 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Dose of corn fertiliser sown at various humidity conditions. * Pest control. The soil is fumigated twice for the control of herbs and twice for insect control. The herbicides used are atrazine at 44% for pre-emergent control and glyphosate at 36% for post-emergent weed control at the doses indicated on the package. The most common insects are the armyworm which is treated with 24% cypermethrin and grasshoppers, treated with 50% malathion. Equation (1) was used to calculate the quantity of pesticides to be used.