Surface run-off water quality from agricultural lands and residential areas

This study was conducted to characterize surface run-off water quality from sugar cane fields, pasturelands and residential areas, and to assess the effectiveness of best management practices (BMPs) in controlling non-point source pollution. From October 2002 to September 2005, the five-day biological oxygen demand (BOD5), total suspended solids (TSS), nitrate/nitrite-N (NO3/NO2-N), soluble reactive phosphate (SRP), total phosphorus (TP), total nitrogen (TN) and pH were determined in surface run-off water from two sugar cane fields, two pasturelands and two residential areas in south-western Louisiana. Faecal coliform counts were carried out on run-off samples from the two pasturelands. The BMPs implemented in one of the sugar cane fields included drop-pipe structures, nutrient management, reduced tillage and the application of herbicides to eliminate summer cultivations, while those implemented in one of the pasturelands included drop-pipe structures, cross-fencing, water points, nutrient management, improved forage planting and managed rotational grazing. Average TSS concentration in surface run-off from the sugar cane fields was significantly higher than the average TSS concentration in the surface run-off from the pastureland and residential areas. Average BOD5 concentrations in surface run-off from the sugar cane fields and pasturelands were significantly higher than the average BOD5 concentration in surface run-off from the residential site. Average TN and NO3/NO2-N concentrations in surface run-off from the sugar cane fields were significantly higher than the average concentration for the pasturelands and residential areas surface run-off. Average TP and SRP concentrations in surface run-off from the pasturelands were significantly higher than the average TP and SRP concentrations in surface run-off from the sugar cane fields and residential areas. The BOD5 was significantly positively correlated with TSS, TN, TP, SRP and NO3/NO2-N. Surface run-off from the sugar cane field with BMPs showed relatively lower median values of TN, TP, NO3/NO2-N and SRP and a slightly higher BOD5 value than the surface run-off from the sugar cane field without BMPs. Similarly, the surface run-off from pastureland with BMPs showed lower median values for TSS, TN and NO3/NO2-N than the surface run-off from pastureland without BMPs.