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Effects of Drain Depth on Nitrate-N and Phosphorus Losses from Drained Agricultural Lands Receiving Nitrogen and Phosphorus from Organic Sources
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.orgCitation: 9th International Drainage Symposium held jointly with CIGR and CSBE/SCGAB Proceedings, 13-16 June 2010 IDS-CSBE-100224.(doi:10.13031/2013.32166)
Authors: Chad A Poole, R Wayne Skaggs, George M Chescheir, M R Burchell
Keywords: Nitrogen, Nitrate, Phosphorus, Drainage, Shallow drainage, Water quality
Nitrate and phosphorus losses from drained agricultural lands are an important environmental concern. Installation of subsurface drainage systems at depths more shallow than typical depths has been proposed as a method for reducing nitrate nitrogen (NO3--N) losses in a manner similar to that of controlled drainage. Data were collected from two drainage systems near Plymouth, NC to determine the effect of drain depth on losses of NO3--N and orthophosphate (OP). Drains in the deep system were 1.5 m deep and 25 m apart while drains in the shallow system were 0.75 m deep and 12.5 m apart. Both plots received swine wastewater applications during the first 31 months of the study (October 2002 to April 2005). Overall, the shallow drain system reduced outflows by 17.1% for this period. No significant differences were observed in the NO3--N concentration of the drainage water between the plots; however, the OP concentration in the drainage water of the shallow plot was significantly higher. NO3--N export was reduced by 9.8% at the shallow drain plot during the course of the study. Results of this study were complicated by the application of N and P as swine wastewater which apparently resulted in preferential flow immediately after applications causing relatively high loads of N and P directly to the shallow drains. This phenomenon would not likely occur in cropland where N and P are applied as inorganic fertilizer. This study was continued on the same site for 36 more months (July 2005 through June 2008) using inorganic N and P as fertilizer. This paper reports the effects of drain depth on NO3- -N and OP losses from the study site when organic N and P fertilizer was used.(Download PDF) (Export to EndNotes)