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Effectiveness of residue and tillage management on water pollutant reduction from agricultural areas
Citation:
Prasad, L., L. Koropeckyj-Cox, A. Thompson, AND F. Arriaga. Effectiveness of residue and tillage management on water pollutant reduction from agricultural areas. ASABE 2021 Annual International Meeting, Virtual, July 12 - 16, 2021.
Impact/Purpose:
Water bodies and coastal areas around the world are threatened by excess nitrogen and phosphorus from upstream watersheds, which can cause rapid proliferation of algae. The algal blooms negatively impact drinking water sources, aquatic species, and recreational services of water bodies by producing toxins, also called harmful and nuisance algal blooms (HNABs). Finding ways to reduce nutrient losses from agricultural fields is paramount for EPA program offices and regional partners. Residue and Tillage management is one of the agricultural conservation practices which has been implemented for reducing nonpoint source pollution.
Description:
Agriculture has been recognized as a significant contributor to water quality degradation. Management practices need continuous assessment and adaptation to obtain sustainability in agriculture and reduce its negative environmental impact. The Residue and Tillage Management Conservation Practice Standard (NRCS 345) is widely applied, however, the overall effectiveness of these practices for water quality improvement is not well understood. A meta-analysis was conducted to understand and quantify residue and tillage management effectiveness on sediment and nutrient losses from agricultural fields. Annual runoff, sediment, and nutrient loads were compiled from published literature across the United States and Canada. A total of 61 research articles were reviewed, and 1575 site-years of data were categorized into four management practices (tillage, no-tillage, tillage with residue cover, and no-tillage with residue cover). Any form of soil disturbance by tillage with 30% residue cover were considered “tillage-residue”. No-tillage was split into two groups to account for conditions when the soil was not disturbed but had residue levels 30% surface residue cover (“no-tillage-residue”). Across the site years (1968-2019), median runoff for no-tillage and no-tillage-residue were 40% and 45% greater than tillage and tillage-residue management, respectively. No difference in median runoff was observed between no-tillage and no-tillage-residue managements. The median runoff for tillage-residue management was 25% lower compared to tillage. Irrespective of residue cover, tillage systems (with and without residue) had 70% greater sediment losses than no-tillage-residue management. Dissolved nutrient (nitrogen and phosphorus) losses were higher in no-tillage systems compared to tillage systems; while total nutrient losses were higher in tillage systems compared to no-tillage systems. Maintaining greater than 30% residue cover reduced dissolved nitrogen and phosphorus losses by 39% and 33%, respectively, across tillage and no-tillage systems. Particulate nutrient losses followed trends in sediment loss, greater sediment loss resulted in greater particulate nitrogen and phosphorus losses. Similar to dissolved nutrients, irrespective of tillage management, greater residue cover decreased total nutrient losses by ~50%. These results indicate that over the long-term, no-tillage and tillage, combined with greater than 30% residue cover can effectively reduce sediment and nutrient losses. However, no-tillage can be effective in reducing sediment and particulate nutrient losses in field conditions with a high risk of erosion.
