Field mobility of bispyribac-sodium herbicide under different rice crop management systems

Abstract

Aerobic rice has been proposed as an efficient management practice to save water and improve rice crop sustainability. However, this technique significantly influences the soil properties and, therefore, can modify the pesticides behavior. Bispyribac-sodium (BYS) is a post-emergence herbicide frequently used in rice agroecosystems but is considered highly toxic to aquatic organisms and dangerous to the environment. This work aims to evaluate the transition from flood irrigation to sprinkler irrigation effects on the persistence and field mobility of BYS. In addition, another variable evaluated was the application of organic amendments. The amendment used was olive pomace compost, an agro-industrial by-product (alperujo) of olive oil processing (almazara). For this purpose, field experiments were carried out, involving six different treatments: Without tillage and sprinkler irrigation (SD) and the equivalent with compost application (SDC). Conventional tillage and sprinkler irrigation (LC) and the equivalent with compost application (LCC) and conventional tillage with flooding (LCI) and with the compost incorporation (LCIC). Traditional techniques in rice cultivation (conventional tillage + flooding) benefit the mobility of the BYS herbicide in the field, assuming a disadvantage for groundwater quality when compared to soils irrigated by sprinklers. In addition, compost application could be considered a strategy to reduce water contamination by BYS and increase its persistence in the most superficial soil layers, especially in aerobic rice systems.