Fig. 34: Revenues at different treatments

and “240 HPS, tending” compared to “240 HPS, pumice”. Costs of electricity per kg yield increased by nearly 15 % for “300 HPS, ungrafted” and even more than 20 % for “300 HPS, grafted” (Tab. 8).

4.5.4 Profit margin

The profit margin is a parameter for the economy of growing a crop. It is calculated by subtracting the variable costs from the revenues. The revenues itself, is the product of the price of the sale of the fruits and kg yield. For each kg of tomatoes, growers are getting about 400 ISK from Sölufélag garðyrkjumanna (SfG) and in addition about 64 ISK from the government. Therefore, the revenues increased with more yield (Fig. 34).

) Revenues (ISK/m 2

25000 22500 20000 17500 15000 12500 10000 7500 5000 2500 0

Price SfG: 400 ISK/kg Price Government: 63.90 ISK/kg

300 HPS, ungrafted 300 HPS, grafted 240 HPS, peat 240 HPS, pumice 240 HPS, scale 240 HPS, tending

Fig. 34: Revenues at different treatments.

When considering the results of previous chapter, one must keep in mind that there are other cost drivers in growing tomatoes than electricity alone (Tab. 7). Among others, this are e.g. the costs for seeds and seedling production (≈ 350 ISK/m2) and transplanting (≈ 300 ISK/m2), costs for plant nutrition (≈ 700 ISK/m2), CO2 transport (≈ 300 ISK/m2), liquid CO2 (≈ 1,500 ISK/m2), the rent of the tank (≈ 400 ISK/m2), the rent of the green box (≈ 300 ISK/m2), material for