Elham Noshadi; Mehdi Homaee; Mohammad Mahmoudian Shoushtari
Volume 15, Issue 2 , July 2017, , Pages 111-128
Contamination from agricultural inputs, particularly herbicides, is one of the most important environmental challenges and the use of modern technologies such as herbigation has intensified this problem. Thus, employing optimal management strategies based on knowledge of herbicide behaviour ...
Contamination from agricultural inputs, particularly herbicides, is one of the most important environmental challenges and the use of modern technologies such as herbigation has intensified this problem. Thus, employing optimal management strategies based on knowledge of herbicide behaviour and processes in soil is necessary. The objective of this study was to assess quantitatively the herbicide adsorption-desorption behaviour in soil in the laboratory and under real field conditions.
Materials and methods:
Consequently, metribuzin was applied to the experimental plots using the herbigation (HRB) and conventional spraying (CS) methods, and to laboratory samples. After inspecting the adsorption and desorption behaviour of herbicide by batch and centrifugal methods, different models of equilibrium adsorption were fitted to the data.
Results and discussion:
Results indicated that, due to the low amount of organic matter and clay in the soil, herbicide adsorption was generally weak in all three types of treatment and that the overall process followed the Freundlich model. The results further showed that in all three treatments because of the adsorption mechanism’s weak hydrogen bond, a large portion of the adsorbed molecules desorbed after four washing cycles. However, in the laboratory and herbigation treatments, the amount desorbed was relatively less and, due to the diffusion of molecules into inter-aggregate pores, a small hysteresis can be seen.
In conclusion the results show, the adsorption amount in laboratory and herbigation treatments is greater than conventional spraying treatments due to a higher moisture level in the soil and increased hydrophilic sites on organic matters and diffusion within the inter-aggregate pores. Therefore, the methods of pesticide application affect the adsorption and desorption behaviour of it. So pesticide application by herbigation is suggested in order to reduce losses and increase efficiency in the field.