Ecotoxicological Footprint Analysis of Rice Cropping Rotations with Different Levels of Intensification

Uruguay, with 147,031 ha allocated to rice production, accounts for approximately 2% of global rice trade, with an average yield of 9,336 kg ha⁻¹. Rice cultivation has historically rotated with pastures, integrating rice–livestock production systems since the 1920s. Recent agricultural expansion has incorporated other crops into the rotation, such as soybean and sorghum, and has increased the frequency of rice cultivation, resulting in more consecutive years of rice and fewer years of pasture return. The Uruguayan National Institute for Agricultural Research (INIA) has conducted a long-term experiment (LTE) since 2012 to evaluate different intensification technologies in rice production systems. Assessments of changes in pesticide use in Uruguayan rice production using the ecotoxicological footprint (EF) indicated that the highest contamination risk was associated with insecticides. This study characterized the agronomic and environmental performance of the LTE using a Life Cycle Assessment (LCA) approach for the period 2012–2019, analyzing six rice-based rotations with different levels of intensification by modifying summer crops and the length of the pasture phase. The EF was estimated using the USEtox model and a modified level-1 fugacity model. Both assessment methodologies allowed discrimination among rotations. The highest impacts were observed in rotations that included rainfed crops, such as soybean and sorghum (R2, R5, and R6), whereas lower impacts were found in rotations without soybean and sorghum (R1, R3, and R4). Rotations with the highest EROI were R4 and R5, while R1, R3, and R6 showed lower EROI values, and R2 exhibited an intermediate value. Overall, R4 emerged as the most sustainable rotation, as it combined the highest EROI with the lowest EF.