In order to address the global food crisis and to promote sustainable food production through efficient use of natural resources and pollution mitigation, collaboration among researchers, policymakers, farmers, and stakeholders is essential to identify hotspots for improvement in cultivation practices. Water plays a crucial role in this process. Wheat ranks as the fourth most-produced staple food worldwide, with 783 million metric tons harvested in 2023.

Despite being the 14th largest global wheat producer, Brazil is actively working on enhancing food security by developing a sustainable wheat production system.

This initiative involves assessing the environmental impact of wheat production through life cycle assessment, focusing on a water ecotoxicity footprint (WEF), encompassing the impact categories of terrestrial, freshwater, and marine ecotoxicities. Impact results are related to 1 kg of grain, with data from 12 rainfed wheat farms in southern Brazil, adopting the scope from cradle to farm-gate.

Emissions of pesticides, heavy metals and nutrients from farm use of inputs were accounted applying the BR-Calc methods. The ecotoxicity impacts were assessed using the ReCiPe 2016 Midpoint (H) V1.08 / World (2010) H method in SimaPRO 9.5.0.2.

Terrestrial ecotoxicity values ranged from 0.43 to 1.96 kg 1,4-DCB eq kg-1, while freshwater and marine ecotoxicities ranged from 0.002 to 0.014 kg 1,4-DCB eq kg-1 and 0.006 to 0.021 kg 1,4-DCB eq kg-1, respectively.

The use of phosphate fertilizers, key input in wheat cultivation, generated emissions that significantly contributed to the WEF (38%, 56%, and 45% for terrestrial, freshwater, and marine, respectively) followed by the wheat cultivation process (37%, 20%, and 37%).

Fertilizer application lead to ecotoxicity due to depositing heavy metals in soil, transported to water resources. Productivity had a direct effect on the WEF, as evidenced by the farm producing 4.5 ton ha-1 of wheat resulting in the lowest WEF values, while the farm yielding 2.5 ton ha-1, the highest.

Thus, increasing the use efficiency of phosphate fertilizers and ensuring higher productivity are the best alternatives to reduce the WEF of Brazilian wheat.