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ARS Home » Midwest Area » St. Paul, Minnesota » Soil and Water Management Research » Research » Publications at this Location » Publication #296364

Research Project: PRACTICES TO PROTECT WATER QUALITY AND CONSERVE SOIL AND WATER RESOURCES IN AGRONOMIC AND HORTICULTURAL SYSTEMS IN THE NORTH CENTRAL US

Location: Soil and Water Management Research

Title: Sorption and leaching potential of isoproturon and atrazine in low organic carbon soil of Pakistan under a wheat-maize rotation

Author
item Tahir, Muhammad - University Of Arid Agriculture
item Hassan, Anwar-ul - University Of Arid Agriculture
item Barber, Brian - University Of Minnesota
item Koskinen, William
item Mulla, David - University Of Minnesota

Submitted to: Pedosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/2015
Publication Date: 10/1/2016
Citation: Tahir, M., Hassan, A., Barber, B.L., Koskinen, W.C., Mulla, D.L. 2016. Sorption and leaching potential of isoproturon and atrazine in low organic carbon soil of Pakistan under a wheat-maize rotation. Pedosphere. 26(5):687-698. doi:10.1016/S1002-0160(15)60077-7.

Interpretive Summary: Limited data are available on the sorption and leaching of pesticides in agricultural soils of Pakistan with low soil organic carbon (OC). Sorption potential of two widely used pesticides, isoproturon and atrazine, was determined using the batch equilibration method on soils from 0-35 cm, 35-70 and 70-110 cm depths from a field of wheat-fallow-maize cropping systems of Faisalabad, Punjab, Pakistan. Leaching potential was estimated under field conditions for 0-35, 35-70 and 70-110 cm soil layers, and in lysimeters packed with the same layers as that of field. In both lysimeter and field studies, leaching was measured under two manure (with and without 50 Mg ha-1 manure) and two flood irrigation levels in a wheat-fallow-maize crop rotation. Isoproturon and atrazine sorption Kd values ranged from 0.3 to 1.2 and 0.4 to 1.5, respectively, and decreased with depth due to a decrease in SOC contents; Kd values showed a significant linear correlation with SOC. The Koc values of isoproturon and atrazine averaged 240 and 185 L kg-1, respectively. Isoproturon residues measured 280 days after application with two manure and two irrigation levels ranged from 2.1-3.6% of the applied mass in the lysimeter and from 1.5-3.1% under field conditions. Atrazine residues measured 65 days after application ranged from only 0.62- 0.78% and from 0.88-2.82% in the lysimeter and field trials, respectively. Lowest levels of residues for both pesticides were observed with frequent irrigation applied to manure amended soil. Both manure application and frequent irrigation were effective in reducing the total soil profile residues of both pesticides in the upper one meter rooting zone of soil. Farmers can now apply manure to their fields, regardless of irrigation levels, knowing they have reduced the leaching risk of these chemicals, and subsequent risk of contaminating ground water.

Technical Abstract: Limited data are available on the sorption and leaching of pesticides in agricultural soils of Pakistan with low soil organic carbon (OC). Sorption potential of two widely used pesticides, isoproturon and atrazine, was determined using the batch equilibration method on soils from 0-35 cm, 35-70 and 70-110 cm depths from a field of wheat-fallow-maize cropping systems of Faisalabad, Punjab, Pakistan. Leaching potential was estimated under field conditions for 0-35, 35-70 and 70-110 cm soil layers, and in lysimeters packed with the same layers as that of field. In both lysimeter and field studies, leaching was measured under two manure (with and without 50 Mg ha-1 manure) and two flood irrigation levels in a wheat-fallow-maize crop rotation. Isoproturon was applied to wheat 55 days after sowing (DAS) after the second irrigation at 1 kg a.i. ha-1, while atrazine 38 SC was sprayed on maize 30 DAS at 0.774 kg a.i. ha-1. Soil was sampled from different depths 288 and 65 DAS of a 2nd dose of isoproturon and atrazine, respectively. Isoproturon and atrazine sorption Kd values ranged from 0.3 to 1.2 and 0.4 to 1.5, respectively, and decreased with depth due to a decrease in SOC contents; Kd values showed a significant linear correlation with SOC. The Koc values of isoproturon and atrazine averaged 240 and 185 L kg-1, respectively. Isoproturon residues measured 280 DAA with two manure and two irrigation levels ranged from 2.1-3.6% of the applied mass in the lysimeter and from 1.5-3.1% under field conditions. Atrazine residues measured 65 DAA ranged from only 0.62- 0.78% and from 0.88-2.82% in the lysimeter and field trials, respectively. Lowest levels of residues for both pesticides were observed with frequent irrigation applied to manure amended soil. Both manure application and frequent irrigation were effective in reducing the total soil profile residues of both pesticides in the upper one meter rooting zone of soil. A pesticide leaching risk screening tool, the ground water ubiquity score (GUS) indicated that in the absence of manure under both irrigation levels, isoproturon had some leaching risks (GUS score ˜2.8), while with the application of manure it had a very low leaching risk. Atrazine GUS scores ranged from 1.7-1.9, indicating a very low risk of leaching.