Effectiveness of denitrification bioreactors with woodchips, corn stover, and phosphate‐sorbing media for simultaneous removal of drainage water N and P in a corn–soybean system. Issue 2 (21st February 2023)

• Record Type: Journal Article
• Authors: Oladeji, Olawale; Tian, Guanglong; Cooke, Richard; El‐Naggar, Essam; Cox, Albert; Zhang, Heng; Podczerwinski, Edward
• Is Part Of: Journal of Environmental Quality. Volume 52:Issue 2(2023)
• Page Start: 341
• Page End: 354
• Publication Date: 2023-02-21
• Subjects: Agricultural ecology -- Periodicals; Environmental engineering -- Periodicals; Pollution -- Periodicals; 630
• DOI: 10.1002/jeq2.20449
• Languages: English
• ISSNs: 0047-2425

Abstract

Abstract: Millions of acres of farmland in the midwestern United States (US) are artificially drained, and this contributes to the export of nitrogen (N) and phosphorus (P) from agricultural land to surface water. Using a 36‐acre tile‐drained farm field, effects of P‐sorbing media in combination with a denitrifying bioreactor system constructed with woodchips (WC) and corn stover (CS) on reducing nutrient export in drainage water were tested for 3 cropping years (2018–2020). The field was divided into three subfields as replicates. In each subfield, the drainage water was divided and separately channeled into three bioreactors, each of which contains one of the three different substrates: WC, CS, and CS–WC (1:1 v/v mixture of CS and WC), randomly assigned. The outlet of each compartment contained a 2.25 L flow‐through chamber filled with activated iron (Fe) filings as P‐sorbing material. Both WC and CS bioreactors were effective in removing drainage NO3 − with a 77% (WC), 86% (CS), and 89% (CS–WC) reduction in mean NO3 − –N concentration. For the three cropping years, the WC bioreactor reduced the total drainage inorganic N (NO3 − –N + NH4 + –N) load by 72%, but the CS bioreactor increased the total inorganic N load in the drainage water due to the substantial release of NH4 + with the decomposition of CS. The breakdown of CS also increased drainage P. The NH4 + and P release decreased with the decrease in the proportion of CS; thus, not more than 10% of CS is recommended for blending with WC to enhance the performance of a bioreactor. The P‐sorbing Fe filing media reduced the P loads in drainage by an average of 19% during the 2‐year study. Core Ideas: Denitrification bioreactors can be complemented with P‐sorbing media as a system for the removal of both N and P in drainage water. Woodchips bioreactors are effective for field‐scale drainage NO3 –N removal in western Illinois. Corn stover as a bioreactor medium releases NH4 + –N from decomposition, leading to an increase in drainage N. Corn stover can be used as a bioreactor medium supplement to the woodchips at about 10%.