Phytoremediation efficacy of native vegetation for excess nitrates, phosphorus and heavy metals on agricultural lands amended with poultry litter and fertilizer

Authors: JAJA, NGOWARI - Oak Ridge Institute For Science And Education (ORISE); CODLING, ETON - Retired ARS Employee; Timlin, Dennis; RUTTO, LABAN - Virginia State University; Reddy, Vangimalla

Submitted to: International Journal of Phytoremediation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2023
Publication Date: 1/16/2023
Citation: Jaja, N., Codling, E.R., Timlin, D.J., Rutto, L., Reddy, V. 2023. Phytoremediation efficacy of native vegetation for excess nitrates, phosphorus and heavy metals on agricultural lands amended with poultry litter and fertilizer. International Journal of Phytoremediation. 1-12. https://doi.org/10.1080/15226514.2022.2161466.
DOI: https://doi.org/10.1080/15226514.2022.2161466

Interpretive Summary: When poultry litter is applied to the soil for increased agricultural yield, it is possible to increase the level of nitrogen, phosphorus, and heavy metals in the soil with the potential to leach to ground water. For two years, we allowed natural and native vegetation to grow on a prepared land and monitored the types of plants/species growing. The goal was to determine if native vegetation could remove excess nutrients and metals in the soil and prevent them from going to the ground water. We also installed instruments into several plots to the depth of 30cm, 60cm and 90cm to measure nitrogen concentration in the soil water. We found that the plots which received poultry litter had more yield than the plots without poultry litter. There were high levels of N in the subsoil suggesting that when using poultry manure, the rates should be decreased to better match N uptake by the native vegetation or any crop being grown. The research showed that these native vegetations could be used in agricultural fields to help remove excess nitrates, nutrients and heavy metals after a long-term poultry litter and fertilizer applications.

Technical Abstract: Poultry litter applied on agricultural lands as fertilizers could introduce excess nitrogen (N), phosphorus (P), and heavy metals into the soil and ground water. Native vegetation (different species) plots were identified to assess their efficacy for phytoremediation of excess N, P and heavy metals from soil and water in the surface and sub-surface horizons. The objective was to measure the capability of a multi-year native species system to remove heavy metals, N and P, and prevent Nitrate-N ((NO3-)-N) leaching below the rooting zone. Treatments were distributed in a completely randomized design with four replicates, with and without the litter/fertilizer applications. Suction lysimeters were installed at 30, 60, and 90-cm depths in 3 of 4 replicates per treatment where native vegetation of different species were observed. The species were identified and recorded, and five specified cuttings taken when applicable. Plant, soil, and water samples were prepared and analyzed for heavy metals and nutrients (Ca, Cu, Fe, K, Mg, Mn, P, Pb and Zn) using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). Nitrate-N with KCL extraction and nitrates in the water samples were determined using a Lachat instrument. The fertilized plots (NVM) had biomass yield that was 39% more than the unfertilized plots (NVN). In plants, nutrient and metal concentrations varied significantly among the harvest with a 14% increase in Zn, as well as 36% and 26% in K and Mg over NVN for first and second year respectively. Though uneven between NVM and NVN, the topsoil had higher values for almost all the nutrients and metals. The largest P and (NO3-)-N in plant and water samples were observed from NVM. The cultivation of native vegetation appears to be an effective approach for remediation of excess nitrates-N, P, and heavy metals in the surface and sub-surface zones of the soil. Keywords: Native Vegetation, Nutrients, Poultry Litter, Water Quality, Heavy Metals, Nitrates.