World Applied Sciences Journal 26 (5): 583-587, 2013 ISSN 1818-4952 © IDOSI Publications, 2013 DOI: 10.5829/idosi.wasj.2013.26.05.12227 Corresponding Author: Said Hassan, Department of Agricultural Chemistry, The University of Agriculture, Peshawar, Khyber Pakhtunkhwa-Pakistan. 583 Assessment the Leaching Potential of Pendimethalin and its Transformation Products in Soil Khalid Mahmood, Mohammad Suleman, Said Hassan, Shah Khalid Badshah 1 1 1 2 Department of Agricultural Chemistry, The University of Agriculture, Peshawar, KPK, Pakistan 1 Department of Botany, Hazara University Mansehra Pakistan 2 Submitted: Oct 11, 2013; Accepted: Nov 11, 2013; Published: Nov 23, 2013 Abstract: Herbicides and their transformation products (TPs) have been reported in ground and surface water and can pose a potential risk to non-target organisms and environment. Therefore, the present study was aimed to investigate the leaching potential of pendimethalin (both aged residue and freshly applied) atrazine and their TPs in silty loam soil. Different doses (recommended application rate i.e; X and 10X) of pendimethalin and atrazine (used as reference) were applied to the disturbed soil columns under controlled laboratory conditions. A simulated rainfall of 90 mm per week was applied to each soil core, considering the worst case scenario. The leachate from the each soil core was collected on weekly basis while the leachate from the aged residue was collected after the application of 2L of artificial rainfall. Solid phase extraction was used to extract the pendimethalin, atrazine and their TPs from the leachates followed by the analysis via reversed phase high performance liquid chromatography (HPLC). Atrazine was found more mobile and detected in the leachate of all the samples collected weekly, while no pendimethalin was detected in the leachates collected from soil cores with X application rate. However, pendimethalin was detected in the leachates of week 11 and 12 collected from the soil cores treated with 10X application rate. 3 unknown compounds that might be the TPs of pendimethalin were detected but too low to quantify. It can be concluded that pendimethalin has poor leaching tendency in silty loam soil as compared to atrazine. At a very high application rate, however, pendimethalin can impose a risk to ground water. Key words: Pendimethalin Soil core Application rate Leaching Leachate INTRODUCTION control annual grasses and broad leaved weeds in Herbicides play important role in the production of process by inhibiting the formation of the microtubule agricultural yield by protection the crops from pests. The protein, tubulin [7]. It is a low mobile having low large use of herbicides and other pesticides in agriculture water solubility and low volatile herbicide [8]. causes serious environmental problems through leaching Pendimethalin adsorbs rapidly and strongly to soil and run-off from the site of application. Persistent particles and organic matter because of its high potential herbicides remain to the soil surface and contaminate for hydrogen bonding. Its persistence in the soil is surface water and also effect the yield of the next crop affected by soil temperature, cultivation and moisture cultivated on the same land [1, 2]. The persistence conditions [9]. herbicides may affect animal health and non-target plants. Herbicide leaching through soil is particularly Various processes such as adsorption, transformation important in a number of environmental and agronomic process in addition climatic conditions, agricultural problems [10]. Herbicides leaching is considered as the practices, soil and herbicides properties are governed the main cause of groundwater contamination by [11], which fate of applied herbicides in the environment [3-6]. is largely determined by physical and chemical properties Herbicide pendimethalin N-(1-ethylpropyl)-2, 6- of herbicides.. Leaching and transport of herbicides may dinitro-3-4 xylidine is dinitroaniline group-containing not only result in low efficacy, but also causes compound used as selective pre-emergence herbicide to groundwater contamination [12-14]. field crops. Pendimethalin interfere with the mitotic