Understanding subsurface hydrology of controlled drainage (drainage water management) and saturated buffers to optimize nutrient reduction goals in Illinois

Nitrate and dissolved reactive phosphorous (DRP) export from artificial subsurface drainage systems (tile drains) underlying agricultural fields can be a major source of reactive N and DRP in surface waters. Conservation drainage practices can help mitigate these nutrient exports while maintaining crop yield. The practice of controlled drainage (or drainage water management) and the relatively new practice of saturated buffers have shown potential for nutrient loss reduction in the US Midwest. However, these two practices were not included in Illinois Nutrient Loss Reduction Strategy (NLRS) due to the limited data available when the strategy was initially developed. Therefore, the overall objectives of this dissertation research were to (i) assess the suitability of controlled drainage for the Illinois landscape while evaluating the extent of lateral seepage when controlled drainage is being implemented, and (ii) evaluate the performance and possible application of saturated buffers in Illinois and across the Midwest. Results from 10 site-years at three saturated buffers showed NO3-N removal similar to studies conducted in Iowa, at 48 ± 19% reduction. The subsurface hydrology of two saturated buffers showed an order of magnitude difference between flow rates at which bypass was initiated despite the two providing relatively similar NO3 removal. A Geographic Information System (GIS)-based estimation showed 75,520 km of stream banks were suitable to host a saturated buffer in the US Midwest, which could contribute a 5-10% regional N load reduction. Controlled drainage reduced nutrient loss by reducing drainage flow volumes at the three sites; the best free vs. controlled drainage comparison showed 41 - 93% annual NO3 loss reduction. However, lateral seepage was documented at the field/zone boundaries which may have led to overestimated nutrient load reductions. Lateral seepage estimated using Dupuit's formula showed 8 – 23 % drainage flow reduction during CD. Together, these findings resulted in the inclusion of saturated buffers as a recommended practice in the Illinois NLRS as of 2021. Controlled drainage showed potential in Illinois while the estimated lateral seepage differed from site characteristics and field management, which further research remained.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Crop Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Chandrasoma, Janith M

Contributors dc:contributor

• Christianson, Laura E
• Christianson, Reid D
• Davidson, Paul C
• Cooke, Richard A
• Lee, Dokyoung

• Saturated Buffers
• Controlled drainage
• subsurface drainage
• nitrate
• dissolve reactive phosphorous

Statement dc:rights

• Copyright Janith M Chandrasoma

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/115550

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F115550