Concentration Weathering of some Agrochemicals in Runoff and Soil Interface on the National Centre for Agricultural Mechanization (NCAM) Farm, Ilorin, Nigeria

Abstract

Agrochemicals are needed to boost agricultural productivity, but substantial quantities are either transported into surface water through runoff or leached into groundwater, which may eventually lead to environmental degradation and pollution. Although several studies have been carried out on the effects of agrochemicals o soil and water qualities but the rate of dissipation of agrochemicals along their pathways are not fully understood yet. The aim of this study therefore was to investigate the level of dissipation of agrochemical elements and compounds as they moved along the furrow. Four experimental fields - NPK fertilizer, urea fertilizer, pesticides (organochlorine) and herbicides (glyphosate) were prepared for this study. The selected agrochemicals were applied on the experimental field and the concentration of chemical elements (electrical conductivity, pH, nitrogen, phosphorus, manganese, zinc, magnesium, potassium, glyphosate and organochlorine) along the furrow were measured at intervals (1 m on a 20 m row) using standard techniques. The range of electrical conductivity, pH, nitrogen, phosphorus, manganese, zinc, magnesium and potassium concentrations for runoff from NPK fertilizer applied field were: 95.75 - 174.51 µS/cm, 5.72 - 7.54, 0.21 - 0.68%, 0.09 - 0.36%, 0.1 - 0.47 mg L-1, 0.25 - 0.66 mg L-1, 4.63 - 7.88 mg L-1 and 7.28 - 16.15 mg L-1; for runoff from Urea fertilizer applied field, the range were: 176.25 - 186.33 µS/cm, 7.14 - 7.64, 0.21 - 0.48 %, 0.21 - 0.38%, 0.41 - 0.65 mg L-1, 0.23 - 0.49 mg L-1, 5.48 - 7.64 mg L-1and 8. 23 - 10.46 mg L-1. The range of electrical conductivity, pH, nitrogen, phosphorus, manganese, zinc and magnesium concentrations for runoff from glyphosate applied field were: 114.00 - 283.78 µS/cm, 6.49 - 7.82, 0.13 - 0.67 mg/kg, 0.03 - 0.09%, 0.41 - 1.60 mg L-1, 0.45 - 2.59 mg L-1, 8.35 - 12.76 mg L-1; and for runoff from organochloride applied field the range were: 344.37 - 380.48 µS/cm, 6.66 - 7.86, 0.30 - 0.56 mg/kg,  0.05 - 0.18%, 0.68 - 0.91 mg L-1, 0.81 - 1.45  mg L-1 12.48 - 14.68 mg L-1. The concentration of agrochemical elements and compounds disintegrate along the furrows on all agrochemical fields except in the case of pH.