A review of agricultural practices and technologies to reduce the - - PowerPoint PPT Presentation

Cynthuja Partheeban, Jeppe Kjaersgaard, Christopher Hay, and Todd Trooien Department of Agricultural and Biosystems Engineering,

A review of agricultural practices and technologies to reduce the nitrate nitrogen load in tile drainage water

• Introduction
• Agricultural practices to reduce nitrogen load in tile

drain water

– Improved nitrogen management – Crop rotation, cover cropping, and tillage – Controlled drainage systems – Constructed wetlands – Riparian buffers – Denitrifying bioreactors

• Summary

Outline

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Introduction

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• Nitrate-nitrogen causes eutrophication in

aquatic ecosystems, health hazard

• Critical need to develop practices to treat tile

drain water

Introduction

Source: Wikipedia.com

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• Timing of N application at appropriate rate
• Changing the timing of pre-plant single application of N from

fall to spring – annual nitrate-N losses 36% reduction (Randall and Vetsch, 2002)

• Application of recommended rate
• Nitrification inhibitors
• Help slowdown the conversion of ammonia to the more

leachable nitrate by limiting the activity and population of Nitrosomonas bacteria(Stehouwer and Johnson, 1989)

Improved nitrogen management

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• Crop rotation
• Nitrate-N concentration in shallow groundwater:

23mg/l under continuous corn 14mg/l under corn-soybean rotation (Kanwar, 2006)

• Extra N fertilizer needed for continuous corn cropping

14-36% higher nitrate-N found in subsurface drainage compared to rotating cropping system (Helmers et al., 2012)

Crop rotation, cover cropping

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• Cover cropping
• Reduce subsurface drainage discharge
• 11% discharge reduced compared to no cover crop
• Reduce nitrate-N loss in subsurface drainage
• 13 % nitrate –N loss reduced compared to no cover crop

(Strock et al., 2004)

Crop rotation, cover cropping

A field of collards with cover crops: mix of rye, hairy vetch, and crimson clover (McGee, 2012)

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Illustration of regulation of water table level by controlled structure, Source: Purdue University

• The outlet elevation is raised or lowered
• Reduction in drain outflow – less nitrate-N loss
• A 61% nitrate-N load reduction on average annually by

controlled drainage (Cooke and Verma, 2012).

• An average load reduction range from 18% to over 75 %

depending on the drainage system design, location, soil, and site conditions (Skaggs et al 2012)

Controlled drainage systems

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Schematic of wetland

• Reduction of nitrates to gaseous N2 or N2O through the

denitrification process

• 23-35% nitrate removal by wetlands (Karpuzeu, 2012;Kovacic et

al.2000)

• Possible limitations:

Additional land required Low removal compared to bioreactor

Constructed wetlands

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Saturated buffer – field tile drainage water is routing into buffer zone, Source: Dan Jaynes, USDA ARS

• Prolonged contact of drainage water with the root zone offers

high nitrogen uptake by plants and an opportunity for the denitrification process to occur

• Study showed nitrate-N reduction from 15 mg/l to 2 mg/l by

riparian buffers (Evans et al., 1996)

Riparian buffers

Denitrifying Bioreactor

Presence of N Oxides (Electron acceptors) Denitrifying Bacteria Suitable DO conditions Carbon source (Electron donor) pH and temperature NO3

• N2

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Denitrifying woodchip bioreactor

Site Reference Percent of reduction Nitrate-N removal rate

Ontario, Canada (Blowes et al., 1994) >99% 10-60 L/d Central IA (Jaynes et al., 2008) 55 % 0.622 g N/m3/d Southern Ontario, Ca (Elgood et al., 2010) NA 0.3-2.5 mg N/L New Zealand (Schipper et al., 2010) NA 2-22 g N /m3/d Decatur, IL (Chun et al., 2010) 47% NA Alachua, FL (Schmidt and Clark, 2012) 65% (load reduction) NA Perkin IA (Christianson et al., 2012a) 22-74% 0.38-3.78 g N/m3/d Montrose, SD (Partheeban et al. 2014) 51% 0.98 g N/m3/d

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Denitrifying woodchip bioreactor

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Denitrifying woodchip bioreactor

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Denitrifying woodchip bioreactor

Average nitrate N load enter into the bioreactor

3.5 lb/ac/year

Average nitrate N load exit from the bioreactor

2.8 lb/ac/year

Average reduction of nitrate N load by the bioreactor

0.7 lb/ac/year (20% load reduction)

N2

BIOREACTOR

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Cost analysis

Name of the practice Cost per Kg N removal (US $) Reference Wetlands 2.91 (Hyberg, 2007; Jaynes and Isenhart, 2013) Riparian buffer 2.25 (Jaynes and Isenhart, 2013) Control drainage management 1.45-2.05 (Cooke et al., 2006) Fall planted cover crops 6.77 (Jaynes and Isenhart, 2013) Bioreactor 2.39-15.17 (Schipper et al., 2010) 8.68 (Partheeban et al., 2014)

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• Additional practice is required to treat tile drain water
• Wetlands, riparian buffers – cost effective, additional

land required

• Controlled drainage systems – low removal rate

compared to other practices

• Denitrifying woodchip bioreactor – less land, cost

effective, relatively high removal rate

Summary