Abstract
ABSTRACT Atrazine still is a widely used herbicide in tropical soils to control annual broad-leaved weeds and annual grasses mainly in maize and sorghum plantations. Sorption and desorption in such soils are important processes that affect transport, ending with soil and water contamination, not only in these soils, but in other soils around the world. Lime and phosphate are important amendments in tropical soils to mitigate low fertility. These treatments can affect interaction among soil particles and between soil and atrazine. The objectives here were to evaluate the effect of lime, phosphate, and lime + phosphate treatments on sorption and transport of atrazine in a Typic Hapludult, using soil-erosion-plots at field conditions in a 3%-slope landscape 20 m away from the floodplain. Water- and sediment-sampler devices were used to measure runoff during an entire rainy season. Soil, water and sediments were sampled and analyzed for atrazine. By increasing pH and changing soil organic matter interaction with mineral particles, lime and lime + phosphate decreased sorption in the upper 20-cm layer. This affected leaching and runoff of atrazine, showing that when lime and lime + phosphate were applied to soil, this herbicide had more potential to go deeper in the soil profile, towards the groundwater, or to runoff towards the lower part of the landscape. However, even with increasing leaching, the amount of rainfall, and water infiltration, were enough to dilute atrazine into levels below the maximum contaminant level (MCL) of atrazine in drinking water.
Highlights
Atrazine is an herbicide which is widely used in maize (Zea mays) crops (Aquino et al, 2013; Pignati et al, 2017), and has been employed for more than three decades to control annual grasses and broad-leaved weeds
Sorption and transport of atrazine have been widely studied in laboratory experiments and in fields were this product has been used for long time
Sorption of atrazine In a previous kinetics assay, it was found that 24 h of shaking was enough time to achieve equilibrium, and it did not differ between the two soil layers (Figure 4)
Summary
Atrazine is an herbicide which is widely used in maize (Zea mays) crops (Aquino et al, 2013; Pignati et al, 2017), and has been employed for more than three decades to control annual grasses and broad-leaved weeds. Sorption and transport of atrazine have been widely studied in laboratory experiments and in fields were this product has been used for long time. Soil tillage may affect infiltration as well as surface runoff and soil moisture and interfere on the potential for sorption and transport, ending with groundwater pollution, especially in soils with a long history of atrazine application (Barrios et al, 2019). Soils play the role of natural filters during the process of sorbing organic contaminants applied to control pests, diseases, and weeds, such as insecticides, nematicides, fungicides, and herbicides. All these contaminants may impact soils and water, and affect human health (Arora; Sahni, 2016). Its use has been banned in many countries, such as in European Union (Sass; Colangelo, 2006), it is still broadly used in Brazil (Pignati et al, 2017)
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