Ecological Engineering 68 (2014) 270–278 Contents lists available at ScienceDirect Ecological Engineering journal h om epa ge: www.elsevier.com/locate/ecoleng Effects of biosolids on biodiesel crop yield and belowground communities Karen L. Adair a,∗ , Steve Wratten a , Anna-Marie Barnes a,1 , Benjamin R. Waterhouse a , Michael Smith a , Gavin Lear b , Paul Weber c , Mark Pizey d , Stéphane Boyer a,e a Bio-Protection Research Centre, Lincoln University, PO Box 85084, Lincoln 7647, New Zealand b School of Biological Sciences, The University of Auckland, 3a Symonds Street, Auckland 1010, New Zealand c O’Kane Consultants (NZ) Ltd, RMB 55037, Castle Hill Village, Christchurch 8154, New Zealand d Solid Energy New Zealand Ltd, 15 Show Place, Addington, Christchurch 8024, New Zealand e Department of Ecology, Lincoln University, PO Box 85084, Lincoln 7647, New Zealand a r t i c l e i n f o Article history: Received 7 November 2013 Received in revised form 1 March 2014 Accepted 31 March 2014 Available online 4 May 2014 Keywords: Biosolids Biodiesel crops Automated ribosomal intergenic spacer analysis (ARISA) Earthworms Heavy metals Seed yield a b s t r a c t Biofuels are an attractive alternative for fossil fuels and demand is growing rapidly, however the environmental impacts of biofuel production must be minimized. Replacing conventional fertilizers with biosolids, processed solids from municipal wastewater treatment plants, has the benefit of utilizing a waste stream and avoiding some of the environmental impacts associated with conventional fertilizers, but the impacts of heavy metals in biosolids must be assessed. In a pot trial, we grew two oilseed crop species, Brassica napus and Camelina sativa, in soil amended with two levels biosolids and soil amended with urea. Seed yield and oil content were compared between soil treatments, and effects on soil chem- istry, activity of microfauna, and bacterial and fungal community structure were quantified. We also measured the impacts of biosolids addition on the growth, survival and tissue chemistry of earthworms. Seed yield of plants grown in biosolids was comparable to or greater than that of plants fertilized with urea. Biosolids addition increased soil concentrations of plant nutrients, but also heavy metals (e.g. arsenic, lead, chromium and nickel). Microfaunal activity, as well as soil microbial community structure, was impacted by both fertilizer type and oilseed plant species. Earthworm biomass was enhanced by addition of biosolids though earthworms exposed to biosolids had elevated levels of copper. Our results suggest biosolids could effectively fertilize these oilseed crops and may enhance soil health, but impacts of heavy metals should be considered. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Liquid fuels produced from renewable biological materials are an attractive alternative to fossil fuels with the potential to reduce greenhouse gas emissions and increase energy independence. Many governments have established biofuel production targets, and as a result global demand is expected to double from levels experienced in years 2005–2007 by 2017 (Bringezu et al., 2009). ∗ Corresponding author. Current address: School of Biological Sciences, Private Bag 4800, University of Canterbury, Christchurch 8140, New Zealand. Tel.: +64 3 364 2987x3820. E-mail address: Karen.adair@canterbury.ac.nz (K.L. Adair). 1 Current address: The New Zealand Institute for Plant & Food Research Limited, Private Bag 4704, Christchurch Mail Centre, Christchurch 8140, New Zealand. However, for biofuels to be a sustainable alternative to fossil fuels the energetic costs of production and environmental impacts must be minimized (Pickett et al., 2008; Zah et al., 2009). The transportation sector contributes significantly to global warming with 10% of this radiative forcing attributed to CO 2 emissions from road transport alone (Fuglestvedt et al., 2008), and there is a global shift in demand from gasoline to diesel fuel (OPEC, 2012; Conti et al., 2013). Half of the transport fuel consumed in New Zealand is diesel (New Zealand Ministry of Economic Development, 2011) making biodiesel a potentially important way to reduce the country’s greenhouse emissions. Oilseed crops, grown as break crops in 3–4 year rotation with cereals, are a part of the New Zealand biodiesel industry and may be used to produce high quality biodiesel following the transesterification of plant oils. Previous research has identified Brassica napus (or canola) and Camelina sativa as biodiesel crops that are particularly adaptable http://dx.doi.org/10.1016/j.ecoleng.2014.03.083 0925-8574/© 2014 Elsevier B.V. All rights reserved.