Pesticide Residues and Their Degradation Products as Influenced by Acidity and Organic Matter in Kura Irrigation Farmland Soils

Abstract

The aim of this research is to determine the insecticide and herbicide residues and their degradation products in Kura irrigation farmland soils. The analyses were carried out during the planting (before harvest) and after the harvesting periods. The insecticide residue analyses were undertaken using Gas chromatography-mass spectrometry (GC/MS) after extraction with a mixture of n-hexane and acetone (1:1) in a soxhlet extractor. The pH levels of the soil samples and the soil organic matter were also determined using standard analytical methods. The acidity and organic matter content of most of the soil samples increased slightly after harvest. The compounds detected as residues include 1-octadecene, 9-heptadecanone, (E)-3-eicosene, (Z)-5-nonadecene, heptadecane, 1-docosene, 1-nonadecene and 1-eicosene. Out of these residues, 1-octadecene and (E)-3-eicosene were detected during planting and after the harvesting periods, showing that they are the most persistent of the residues in the soil samples. The residues detected before harvest were totally different from the residues detected after harvest. This shows that the pesticides, after some time, degraded in the soil into completely different compounds and the total residues were detected in high percentages.