Worksheet(s) in the FABLE Calculator:
⇒ 3_calc_crops
⇒ 3_data_crops
For crops, the starting points are human and feed demand which have been computed during the previous steps (cf. Human demand and Feed). Then we compute imports by multiplying the sum of human demand and feed demand with the share of the consumption which is imported according to the selected import scenario, and exported quantity is taken from the selected export scenario (cf. Trade). According to the FAO, post-harvest losses include "waste during the year at all stages between the level at which production is recorded and the household” (i.e. storage and transportation). We compute the share of losses for each commodity in each country as the historical losses quantity over production plus imports plus stock withdrawals, based on historical data from the FAO Commodity balance. We keep the share constant at 2010 levels for the rest of the period 2015-2050. This parameter could typically be subject to alternative scenarios in the future. Stock variation is only included for historical years using FAO statistics and assumed null for the rest of the period. Targeted production is computed as targeted human consumption, plus targeted feed consumption, plus targeted exports, minus imports, plus losses, minus stock variation.
An additional demand for crops comes from processing. This is related to the human and feed demand of processed commodities such as vegetable oils or refined sugar. Targeted production or processed commodities is computed as described in the previous paragraph but an additional computation step is required to compute the quantity of raw product (crop) which is needed to produce the targeted production of the final product. We compute the processing coefficient as the reported production level of a processed product divided by the reported processed quantity of the raw product which is used as input in 2010 according to FAO Commodity balance (e.g. the production of sunflower oil divided by the sunflower quantity which is reported as processed). Targeted production is the sum of the targeted production of a crop which is used as the final product and the targeted production of a crop which is used for processing. In fact, several products can result from the processing of the same input (e.g. after extracting the oil from oilseeds, oilseed cakes which are left over can be used for animal feed). In order to convert the targeted production into harvested areas, we need to select the targeted input production for the production of a single final processed product to avoid double-counting.
Harvested area is computed as the total targeted production of a crop divided by the average annual yield in ton per hectare. This productivity is taken from FAOSTAT for 2000, 2005, and 2010 and depends on the productivity scenario which is selected for the period 2015-2050 (cf. Productivity). In some countries, several harvests are possible during the year resulting in lower cropland area than the total harvested area per year. We compute the average harvesting coefficient as the sum of all harvested area per crop divided by the total cropland area using historical FAO data. If the total harvested area is lower than cropland area, the harvesting coefficient is set to 1. The planted area is obtained by dividing the harvested area by the harvesting coefficient.
