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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #416029

Research Project: Sustainable Intensification in Agricultural Watersheds through Optimized Management and Technology

Location: Agroecosystems Management Research

Title: Impact of tillage, cover crops, and in situ bioreactors on nutrient loss from an artificially drained Midwestern Mollisol

Author
item Rogovska, Natalia
item Kovar, John
item Malone, Robert
item O'Brien, Peter
item Emmett, Bryan
item Ruis, Sabrina

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2024
Publication Date: 12/25/2024
Citation: Rogovska, N.P., Kovar, J.L., Malone, R.W., O'Brien, P.L., Emmett, B.D., Ruis, S.J. 2024. Impact of tillage, cover crops, and in situ bioreactors on nutrient loss from an artificially drained Midwestern Mollisol. Journal of Environmental Quality. https://doi.org/10.1002/jeq2.20668.
DOI: https://doi.org/10.1002/jeq2.20668

Interpretive Summary: Soil nutrient loss to surface waters is a key factor causing degradation of water quality and present economic loss to farmers. A study was initiated to quantify the effectiveness of management practices on leaching of essential crop nutrients from artificially drained agricultural land. Corn and soybeans were grown under five management scenarios: 1) BP-basic practice with fall chisel plow; 2) NT: no-till crop production; 3) RC: no-till with a winter rye cover crop; 4) DW: no-till with woodchip denitrification walls parallel to both sides of the tile; and 5) ZN-zero N; no-till without N fertilization. Compared to BP, in-situ bioreactors reduced nitrogen loss by 47% due to denitrification, but increased potassium loss presumably due to decomposing woodchips. Despite no application of nitrogen fertilizers, on average ZN plots lost as much nitrogen as optimally fertilized BP plots. Rye cover crop was effective in reducing nitrogen loss, but had no impact on leaching of potassium, sulfur, and total phosphorus. Conventionally managed corn produced the highest yields with significant yield penalty occurring in unfertilized plots, while soybean yields were not impacted by management practices. The finding of this research will be useful to farmers, agricultural professionals, and outreach specialist who are considering implementation of various conservation practices and their impact on water quality.

Technical Abstract: Nutrient losses via subsurface tile drains cause environmental degradation of aquatic ecosystems and present an economic loss to farmers. Conservation practices such as cover crops and bioreactors, reduce nitrate leaching and discharge in tile drainage; however, studies on leaching of other nutrients are limited. A replicated plot experiment was initiated to quantify the effectiveness of conservation practices on leaching of NO3-N, total P, K, and S from drained soils from 2016 to 2022. Corn (Zea mays L.) and soybean [Glycine max L Merr.) were grown under five different treatments: 1) BP-basic practice with fall chisel plow; 2) NT: no-till crop production; 3) RC: no-till with a winter rye (Secale cereale L.) cover crop; 4) DW: no-till with woodchip denitrification walls parallel to both sides of the tile; and 5) ZN-zero N; no-till without N fertilization. Compared to BP, both RC and DW treatments reduced NO3 load by 63 and 47%, respectively; 15.5, 5.8, and 8.2 kg N ha-1 yr-1. The DW resulted in twice as much K loss compared to BP, presumably due to decomposing woodchips. Treatment had no impact on S or P loads, however, NT plots lost 47% more P than BP plots: 0.21 vs 0.14 kg P ha-1 yr-1, respectively. The BP produced the highest corn yield, whereas soybean yields were not affected by treatments. Overall, precipitation and drainage discharge had the greatest impact on drainage loss of all nutrients, whereas treatment had statistically significant impact only on N and K losses.