Assessment of Irrigation Water Quality for Dry-Season Green Vegetable (Amaranthus crentus L.) Farming in Ondo State, Nigeria

The need to meet the all-year round green vegetable demands of the ever-growing population, especially in the urban and peri-urban towns of Ondo State, has made dry-season irrigation inevitable. Moreover, dry-season green vegetable farming provides an opportunity for smallholder farmers to further extend their cropping season, increase productivity, and ultimately improve their earnings. Thus, the aim of the present study was to carry out an assessment of irrigation water quality for dry-season green vegetable (Amaranthus crentus L.) farming in Ondo State, Nigeria. Ten (10) water samples covering at least three (3) major towns/cities in each of the three senatorial districts were collected from different green vegetable farms across the state during the dry season. Thereafter, samples of water collected were taken to the laboratory for both physicochemical and microbial analyses. Mean values of physicochemical parameters such as pH (6.12), EC (338.8 µS/cm), turbidity (4.03 NTU), TSS (0.428 mg/L), TDS (169.4 mg/L), and BOD (2.141 mg/L) were within the permissible levels, while COD (154 mg/L) and total hardness (135.24 mg/L) were above the limits. Microbial analysis also showed that total viable coliform counts (TVCC) were higher than the recommended limit, while total viable E. coli counts (TVEC) fell below detectable levels. Therefore, it was concluded that the irrigation water used for dry-season green vegetable farming in Ondo State was relatively of good quality, which serves as an encouragement to both farmers and consumers of the vegetable. However, given the higher levels of total hardness and TVCC, continuous monitoring and assessment of irrigation water quality in the state, especially beyond the areas presently covered, and awareness campaigns against urban surface water pollution to prevent potential faecal contamination of the sources and avert possible ingestion of pathogenic organisms through the consumption of green vegetables are recommended.