Meta‐Analyses of Biosolids Effect in Dryland Wheat Agroecosystems

Abstract

Land application to cropping systems is USEPA's preferred method of recycling biosolids. Determination of biosolids effect size through meta-analyses from two decades of field-location research at three sites should answer the question: Does 20 yr of biosolids application affect dryland wheat ( L.) grain production, grain nutrient concentrations, and soil elemental extractability compared with equivalent rates of commercial N fertilizer? At two sites, biennial biosolids application rates to a wheat-fallow (WF) rotation were up to 11.2 dry Mg ha and up to 112 kg commercial N fertilizer ha, whereas rates at the third location varied to match soil-test information. Crop rotations included WF and wheat-corn ( L.)-fallow. We completed meta-analyses of biosolids effects compared with N fertilizer on wheat yield, grain protein, grain total, and soil ammonium bicarbonate-diethylenetriaminepentaacetic acid (ABDTPA)-extractable P, Zn, Cu, Fe, and Ni concentrations at the aforementioned sites from 1993 through 2013. Results showed that biosolids produced greater grain P and Zn at one site. Biosolids rates at two sites resulted in greater grain Zn and ABDTPA P, Zn, Cu, and Fe. Meta-analyses tests for heterogeneity indicated that the variance for all sites and rates could be explained as consistent across treatments, whereas the test for the 20 yr showed that heterogeneity was large and other factors affected the variance (e.g., climatic variability between years). Meta-analysis showed the practical effect of biosolids over a 20-yr study and demonstrated that the primary biosolids effect was an improvement in Zn availability to wheat.

The Clean Water Act and biosolids: A 45‐year chronological review of biosolids land application research in Colorado

“…• Overall effects of biosolids in dryland wheat agroecosystems. Barbarick et al (2017) performed meta-analyses on data collected from the Byers, CO, site (2001CO, site ( -2013 in conjunction with data collected from the "new" North Bennett, CO, site (1993CO, site ( -2013. The research premise was to understand whether biosolids application affects dryland wheat grain production and nutrient concentrations and available soil nutrients as compared with equivalent inorganic fertilizer applications.…”

Assessing the Potential Chronic, Lethal, and Multigenerational Ecotoxicity of Land-Applying Biosolids using Zea mays, Glycine max, Phaseolus vulgaris and Brassica rapa

“…Despite the presence of organic contaminants in biosolids, studies consistently note their minimal concentrations and the net bene t of land-application to soil and crop health (Prosser et al 2014; Barbarick et al 2017;Shahmohamadloo et al 2016), even when applied above conventional agronomic rates. Additionally, the use of biological test organisms in biosolids toxicity testing has expanded through the publication of government guidance documents and standardized operating protocols (SOPs).…”

“…There are exemptions to solely using organism for testing, particularly in measuring the bioaccumulation of hydrophobic compounds, which warrants biochemical assessment (Schmidt and Redshaw 2015;Wu et al 2015;Barbarick et al 2017). Regardless of the approach, whether using whole-organism endpoints or biochemical analysis, biosolids risk assessment has included many compounds including regulated (e.g., mercury) and unregulated inorganics (e.g., silver), steroids, brominated ame retardants (BFRs), silicones, and synthetic musks.…”

“…Lastly, compared to toxicity assessment using terrestrial animals, the literature on ecotoxicology testing using plants has included a larger diversity of organisms by including row crops (i.e., corn, soybean, wheat), horticulture (e.g., radish, lettuce), and riparian vegetation (e.g., lemna minor) (Barbarick et al 2017;Kebrom et al 2019;Venegas et al 2019;Velicogna et al 2020). It must be noted, however, that biosolids are land-applied only on row crops, as opposed to eld-to-fork crops, as, for instance, in the case of horticulture (e.g., radish, lettuces).…”