Evaluation of phytotoxicity of three organic amendments to collard greens using the seed germination bioassay

Selamawit Woldesenbet,Ming Gao,Peter Ampim,Monique Garcia,Ali Fares,Tesfamichael H Kebrom,Ripendra Awal,Haimanote K Bayabil

doi:10.1007/s11356-018-3928-4

Selamawit Woldesenbet, Ming Gao + Show 6 more

Open Access

https://doi.org/10.1007/s11356-018-3928-4

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Abstract

Small-scale vegetable and fruit crop producers in the USA use locally available commercial organic fertilizers and soil amendments recycled from municipal and agricultural wastes. Organic soil amendments provide crops with their nutrient needs and maintain soil health by modifying its physical, chemical, and biological properties. However, organic soil amendments might add unwanted elements such as toxic heavy metals or salts, which might inhibit crop growth and reduce yield. Therefore, the objective of this study was to evaluate phytotoxicity of three commercial organic amendments, chicken manure, milorganite, and dairy manure, to collard greens using the seed germination bioassay and chemical analysis of the organic amendments. The seed germination bioassay was conducted by incubating collard greens seeds to germinate in 1:10 (w/v) organic amendment aqueous extracts. Results of this work identified phytotoxic effects of chicken manure and milorganite, but not dairy manure, to collard greens. Potentially phytotoxic chemicals such as copper, zinc, nickel, and salts were also higher in chicken manure and milorganite compared to dairy manure. In particular, nickel in chicken manure and milorganite aqueous extracts was 28-fold and 21-fold, respectively, higher than previously reported toxic levels to wheat seedlings. The results demonstrate the need for more research on phytotoxicity of commercial organic soil amendments to ensure their safe use in vegetable and fruit crop production systems.

Highlights

IntroductionResponsible editor: Gangrong Shi conventional inorganic fertilizers to organic fertilizers and soil amendments prepared from municipal, industrial, and farm wastes (Wortman et al 2017)
Small-scale vegetable and fruit crop growers are transitioning from conventional farming to environmentally friendly and more profitable semi-organic or organic farming (Reganold and Wachter 2016); they are shifting from usingResponsible editor: Gangrong Shi conventional inorganic fertilizers to organic fertilizers and soil amendments prepared from municipal, industrial, and farm wastes (Wortman et al 2017)
We hypothesized that the observed phytotoxicity could be due to soluble substances in the original material or phytotoxic by-products during the conversion of poultry farm and municipal wastes into chicken manure and milorganite, respectively, that could be washed away in the first extract

Summary

Introduction

Responsible editor: Gangrong Shi conventional inorganic fertilizers to organic fertilizers and soil amendments prepared from municipal, industrial, and farm wastes (Wortman et al 2017). The nutrient content and chemical composition of organic amendments prepared from agricultural and municipal solid wastes could vary depending on their origin and technologies used to convert these bioresources into organic fertilizers or soil amendments (Emino and Warman 2004; Tognetti et al 2005). With higher rates of application, some of the nutrients, heavy metals or salts in organic fertilizers and soil amendments, could reach toxic levels, inhibit crop growth, and reduce yield. Determining phytotoxicity of organic soil amendments prior to their use in agricultural soils is critical for developing sustainable small-scale semiorganic or organic crop production practices that depend on bioresources recycled from municipal, industrial, and farm wastes

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