Irrigation and Drainage
397934 - Water Quality Characterization for Nursery Irrigation and Storm Runoff
Wednesday, June 6
10:30 AM - 12:00 PM
Location: Skyway Room
David Sample, Virginia Beach – Virginia Polytechnic Institute and State University; Jim Owen, Virginia Beach – Virginia Polytechnic Institute and State University
Demand for water has risen considerably, because of population growth and increasing water use by municipalities and agriculture. Hence, sustaining high quality water supplies is increasingly important to both municipalities and agriculture. Large amounts of water in agriculture are applied for irrigation to minimize plant stress. In nursery production, fertilizer needed for plant growth and development is applied as controlled release fertilizer and supplemented via chemigation of fertilizer as needed, some of which runs off, carrying with it nitrogen and phosphorus. Runoff is collected and recycled; however, if discharged it could have negative effects on water quality in receiving water bodies. Characterization of water quality from storm and irrigation runoff from nurseries is an essential step to understanding potential treatment strategies. Several storm and irrigation runoff samples were collected from a mid-Atlantic nursery and analyzed for pH, electrical conductivity (EC), and total suspended solid (TSS). Samples were collected downstream of 5.2 hectare production area including 1.82 ha roads and 3.38 ha container pads, all of which drain to a central receiving ditch. Results indicated that during irrigation, there was a direct relationship between runoff and TSS peaks, i.e., TSS peaks follow peak runoff, with a defined lag. TSS declined at the end of irrigation. During irrigation, EC dropped suddenly, returning back to initial values at the end of the irrigation event, reflecting the arrival of mineral salts associated with fertilizer compounds. During irrigation, pH of runoff varied from 7.8 to 8.2. The theoretical kinematic wave overland flow residence time was conducted for the system (as a collection of idealized planes) and the drainage ditch and compared with the observed patterns for TSS and EC.