The environmental fate and potential impacts of nanopesticides on agroecosystems under realistic agricultural conditions are poorly understood. As a result, the benefits and risks of these novel formulations compared to the conventional products are currently unclear. Here, we examined the effects of repeated realistic exposures of the Cu(OH)2 nanopesticide, Kocide 3000, on simulated agricultural pastureland in an outdoor mesocosm experiment over 1 year. The Kocide applications were performed alongside three different mineral fertilization levels (Ambient, Low, and High) to assess the environmental impacts of this nanopesticide under low-input or conventional farming scenarios. The effects of Kocide over time were monitored on forage biomass, plant mineral nutrient content, plant-associated non-target microorganisms (i.e., N-fixing bacteria or mycorrhizal fungi) and six soil microbial enzyme activities. We observed that three sequential Kocide applications had no negative effects on forage biomass, root mycorrhizal colonization or soil nitrogen fixation rates. In the Low and High fertilization treatments, we observed a significant increase in aboveground plant biomass after the second Kocide exposure (+14% and +27%, respectively). Soil microbial enzyme activities were significantly reduced in the short-term after the first exposure (day 15) in the Ambient (-28% to -82%) and Low fertilization (-25% to -47%) but not in the High fertilization treatment. However, 2 months later, enzyme activities were similar across treatments and were either unresponsive or responded positively to subsequent Kocide additions. There appeared to be some long-term effects of Kocide exposure, as 6 months after the last Kocide exposure (day 365), both beta-glucosidase (-57% in Ambient and -40% in High fertilization) and phosphatase activities (-47% in Ambient fertilization) were significantly reduced in the mesocosms exposed to the nanopesticide. These results suggest that when used in conventional farming with high fertilization rates, Kocide applications did not lead to marked adverse effects on forage biomass production and key plant–microorganism interactions over a growing season. However, in the context of low-input organic farming for which this nanopesticide is approved, Kocide applications may have some unintended detrimental effects on microbially mediated soil processes involved in carbon and phosphorus cycling.
|Journal||Frontiers in Microbiology|
|State||Published - Mar 29 2018|
Bibliographical noteFunding Information:
We want to thank Medora Burke-Scoll, Brooke Hassett, Anna Fedders, Ethan Baruch, Eric Moore, Erin Vanderjeugdt, Samuel Mahanes, Henry Camp, Bradley Shewmaker, Alison Waldman, Lucia Mercado, Wyatt Jernigan, Kristen Buehne, Shannon Thoits, Eva May, and Nia Bartolucci for their help during the set-up of this experiment, field collection, and lab work. We also thank Shristi Shrestha for performing the acid digestion and ICP-MS measurements on the soil and plant samples. Thanks to Caroline Buchanan for her help for the root mycorrhizal colonization measurements. Funding. This work was supported by the National Science Foundation (NSF) and the Environmental Protection Agency (EPA) under NSF Cooperative Agreement EF-0830093 and DBI-1266252, Center for the Environmental Implications of Nanotechnology (CEINT). WT and NC were supported by an NSF-CAREER (3331939). Any opinions, findings, conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF or the EPA. This work has not been subjected to EPA review and no official endorsement should be inferred.
© Copyright © 2018 Simonin, Colman, Tang, Judy, Anderson, Bergemann, Rocca, Unrine, Cassar and Bernhardt.
- copper hydroxide
- microbial extracellular enzyme activities
- mycorrhizal colonization
- nitrogen fixation
- terrestrial mesocosms
ASJC Scopus subject areas
- Microbiology (medical)