Recovering the lost nutrients from subsurface drainage systems towards agricultural sustainability

Progress report for GNC22-361

Project Type: Graduate Student
Funds awarded in 2022: $14,844.00
Projected End Date: 08/31/2024
Grant Recipient: University of Illinois at Urbana-Champaign
Region: North Central
State: Illinois
Graduate Student:
Faculty Advisor:
Rabin Bhattarai
university of Illinois at Urbana-Champaign
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Project Information


Farmers today are under multiple attacks. Supply chain disruptions have pushed global fertilizer prices to unprecedented heights, making it harder for  farmers to make a profit. In the North Central Region, the widely adopted artificial agricultural drainage systems benefit crop growth, but also discharge excess nutrients into waterways, decreasing nutrients use efficiency and leading to eutrophication. In this context, the intensification of agricultural food production in the United States faces daunting challenges in achieving agricultural sustainability.

In response to achieving more circular and sustainable food production systems in North Central Region, our project is dedicated to recovering the lost nutrients from the agricultural drainage systems that can reduce reliance on nutrients imports, increase nutrient-use efficiency, and release environmental pressures. We consider that subsurface drainage systems can be redesigned and treated as nutrient recovery systems rather than the primary cause of nutrients loss from intensive agricultural systems. This requires a shift of traditional conservation practices from nutrient loss reduction to nutrients recovery.

To achieve this goal, this project aims to design next-generation agricultural drainage systems that combine novel end-of-tile nutrients removal-to-recovery (R2) systems. The specific objectives are to: 1) develop sustainable and low-cost adsorbents (agricultural and industrial wastes as feedstocks) that can be used to adsorb and recover nutrients from drainage water; 2) design fillable modules that can easily place the adsorbents and be installed at the existing end-of-tile drainage systems; 3) reuse the spent adsorbents from the modules into the agricultural field as slow- releasing fertilizer and soil amendment. This project examines the feasibility of addressing multiple dimensions of sustainability and exploring agroecosystems potential by keeping nutrients in the closed agricultural loop if lost nutrients can be recovered and reused. The outcome of this project will directly benefit farmers and ranchers through addressing the most pressing issues they encounter: surging fertilizer prices, nutrients loss from croplands, and nutrient-induced water pollution.

We plan to conduct a series of lab and field-scale experiments to evaluate each objective across the entire project in the Agricultural Engineering Research and Training Farm, IL. The graduate student (Hongxu Zhou) will lead the project and meet with the advising professor and farm managers at least once a month to monitor progress and the team will guide the project in a coordinated manner.

Project Objectives:

This project is designed to improve agricultural sustainability by closing the nutrients cycle in the agricultural systems. The learning outcomes are expected to deliver a strong message to farmers, ranchers, and all participants: increasing the use of recycled nutrients and protecting the natural environment are of vital importance to achieving sustainable agriculture. In this project, the traditional best management practices in reducing nutrients loads will be further improved via recovering the lost nutrients from agricultural tile-drainage systems. By doing so, farmers can realize that agricultural practices, even a small step forward, can make a huge contribution to the circular economy and sustainable development. This project will also increase the farmers' motivation and initiative in participating in the Nutrients Reduction Strategy program, as they can receive financial benefits from recovered nutrients without spending extra money on additional fertilizers. Throughout the project, we recognize that farmers are at the forefront of global efforts to protect and regenerate nature. The project requires a series of laboratory and localized field experiments in close collaboration with farmers. The action outcomes of this project are expected to change farmers’ agricultural practices in a more sustainable production manner. That is, farmers will enable to apply the end-of-tile nutrients removal-to-recovery (R2) systems in their croplands and then learn how to reuse the recovered nutrients from the systems for crop growth.


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  • Dr. Wei Zheng (Researcher)


Materials and methods:

This proposal aims to generate designer biochars to effectively capture phosphorus from subsurface tile drainage, recycle phosphorus-captured biochars as a slow-release fertilizer, and keep nutrients in the closed agricultural loop. The overall goal of the project is to develop an innovative practice to minimize phosphorus loading from subsurface tile drainage to nearby watersheds, improve crop yields by enhancing nutrient use efficiency, and thereby increase Illinois agricultural sustainability. To achieve this goal, the following specific objectives will be addressed:

Create designer biochars by pyrolysis of biomass pre-treated with lime sludge. 

Conduct a laboratory experiment to evaluate the sorption capacity of designer biochars for phosphorus, characterize their properties, and thereby optimize biochar production conditions. 

Construct refillable biochar-sorption-channels and use designer biochars to capture phosphorus from subsurface tile drainage by conducting a field study. 

Recycle phosphorus-captured biochars from the channels and apply them as a slow-release fertilizer to improve soil quality and crop yields through conducting a greenhouse trial. 

Research results and discussion:
  • A novel designer biochar was produced from woody biomass treated with lime sludge prior to pyrolysis. The designer biochar exhibited a high sorption performance for dissolved P, suggesting the pretreatment of biomass with lime sludge is a key process to improve the sorption capacity of the designer biochar.
  • Post-sorption characterization and mathematical modeling analyses indicated that the sorption of dissolved P on the designer biochar could be controlled by multiple sorption mechanisms. The precipitation reaction between P anions and metal ions on the surface of the designer biochar was identified as a predominant mechanism.
  • Designer biochar pellets were manufactured under optimal production conditions. A field trial using P-sorbing filters was conducted to evaluate three P sorbents (the designer biochar pellet, a commercial P polymer sorbent pellet, and an iron material). The designer biochar pellets could capture about 43% of dissolved P from drainage water, showing a great potential to prevent nutrient loss from agricultural fields.
  • A two-year field demonstration study had been conducted to investigate P removal from agricultural drainage water using biochar-sorption chambers. The results showed that the designer biochar pellets could capture P (especially total P) from drainage water and reduce nutrient loss. Especially for dissolved P, the capture efficiency of the designer biochar pellets with a small particle size (~1 cm) was significantly higher compared to the larger biochar pellets (> 2 cm) (Figure 2).
  • A combined nutrient treatment system with a woodchip bioreactor and a two-stage biochar-sorption channel was built in a field trial to prevent excess nutrient loss through drainage water. It showed that approximately 67% of nitrate-nitrogen (NO3-N) was removed by the woodchip bioreactor and 15% was captured by the two-stage biochar-sorption channel. In addition, the total losses of dissolved P and total P were significantly reduced after the drainage water passed through the two-stage biochar-sorption channel .
  • A greenhouse experiment had been conducted to investigate the effect of biochar soil application on radish yields. We observed that the addition of both fresh and spent biochars into soils did not improve plant growth, suggesting biochar application into fertile soils may not improve agronomic yields. By contrast, the combined application of biochar and N fertilizer in fertile soils could favor radish root development, resulting in a positive effect on crop yields.
Participation Summary
6 Farmers participating in research

Educational & Outreach Activities

20 Consultations
2 Curricula, factsheets or educational tools
2 Journal articles
4 On-farm demonstrations
2 Online trainings
2 Published press articles, newsletters
3 Tours
2 Webinars / talks / presentations
4 Workshop field days

Participation Summary:

20 Farmers participated
23 Ag professionals participated
Education/outreach description:

One peer-reviewed paper has been submitted and accepted by a peer-reviewed scientific journal.  Zhou, H.; Margenot, A.J.; Zheng, W.; Wardropper, C.B.; Cusick, R.D.; Bhattarai, R. 2023. Advancing circular nutrient economy to achieve benefits beyond nutrient loss reduction in the Mississippi/Atchafalaya River Basin. Journal of Soil and Water Conservation.78 (4) 82A-84A. doi:

Two presentations: 

During October 29, 2023 – November 1, 2023: Hongxu Zhou, Richard A.C. Cooke, Rabin Bhattarai, Wei Zheng. Bioreactor-Biochar (B2) Treatment System: A novel design to remove and capture nutrients from agricultural drainage water. ASA, CSSA, SSSA Annual Meeting St. Louis, Missouri. The graduate student received First Place in Oral Presentation Student Competition in Soils and Environmental Quality Division from SSSA.

During Feb 15: Hongxu Zhou, Sophie Circenis, Richard A.C. Cooke, Rabin Bhattarai, Wei Zheng. (Lightning round presentation & Poster Presentation). Engineering-scale application of designer biochar to capture and recycle phosphorus from tile drainage systems. NREC Investment Insight LIVE. 2024. 02/15/2024. Urbana-Champaign. Illinois.

Upcoming event:

We have another article submitted to the Scientific Journal and two upcoming presentations. 

Information Products

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.