ORIGINAL PAPER Assessment of Two Sheep Wool Residues from Textile Industry as Organic Fertilizer in Sunflower and Maize Cultivation Ahmed M. Abdallah 1 & Francesca Ugolini 2 & Silvia Baronti 2 & Anita Maienza 2 & Fabrizio Ungaro 2 & Francesca Camilli 2 Received: 9 April 2019 /Accepted: 17 July 2019 # Sociedad Chilena de la Ciencia del Suelo 2019 Abstract Sustainable agricultural practices that enhance soil fertility and increase its capacity for carbon sequestration are increasingly needed. This study evaluates two types of sheep wool residues (SWRs)—carbonized (black wool, BW) and non-carbonized (white wool, WW) to enhance soil fertility and act as a N-source. The two SWRs were tested on two plant species, in two pot experiments: ornamental sunflower on soil mixtures with each of SWR types at different concentrations (0, 0.5, 1, and 2% w/w), and maize on BW- or WW-soil mixture (1% w/w) and supplementary N fertilization (0, 50, and 100% of recommended N rates). In sunflower, with the exception of WW at 2%, all SWRs-soil mixtures increased plant growth and biomass production. Lower SWRs concentrations enhanced the growth rate at an initial stage, and in general, BW provided optimal biomass, and flower yield. In maize, the SWRs (1%), especially BW, even without N-fertilization, were beneficial for plant physiological behavior and biomass production. High mineral N-fertilization (100% N with BW1%- or WW1%-soil mixture) resulted in lower biomass than the other BW-treatments. The results highlighted the efficacy of BW on biomass production for both species growing in a sandy-loam soil, and for maize, no need for further mineral N-fertilization. Keywords Organic fertilizer . Organic waste . Plant growth . Plant ecophysiology . Water use efficiency . Yields 1 Introduction Drought events intensified by climate change, along with the increasing demand of fertilizers to achieve maximum crop productivity, have become crucial concerns in agriculture and for the environment. Even the latest Intergovernmental Panel on Climate Change special report (IPCC 2018) recom- mends agricultural measures to increase the carbon dioxide removal from the atmosphere, such as practices that enhance soil fertility and increase carbon sequestration or reduce greenhouse gases emissions (e.g., reducing the amount of fertilizers and mechanization). Also, methods that increase the water use efficiency should be promoted in order to sustain crop yields (Fließbach et al. 2007; Alagöz and Yilmaz 2011). Organic soil amendments or fertilizers, such as agricultural by-products or waste, could be effective solutions (Leskovar and Othman 2018; Truong and Marschner 2018). In Europe, the agricultural sector produces more than 200,000 t per year of coarse wool. Exactly 18,000–20,000 tons are produced in Italy (Zoccola et al. 2015). Such wool is an animal by-product not suitable for the clothing industry as it does not meet the quality standards and, as it is classified as special waste ac- cording to the European Commission (Bhavsar et al. 2016), it is often discarded in landfill. However, several studies clearly indicate beneficial effects of different kinds of wool waste or wool residues on soil properties and fertility. The wool keratins slowly degrade into simpler compounds releasing nutrients in the soil over a long time (Ignatova et al. 1999; Nustorova et al. 2006; Zheljazkov 2005; Zheljazkov et al. 2008; Zoccola et al. 2015). Several authors (Böhme et al. 2008; Suruchi et al. 2014; Zheljazkov et al. 2009) reported that wool-waste retains significant con- centrations of P, Ca, K, Cu, Zn, and Mn, which, once miner- alized, could be used by plants. Each ton of raw wool contains nearly 640 kg of wool fiber, 150 kg of lanolin (if not scoured), Electronic supplementary material The online version of this article (https://doi.org/10.1007/s42729-019-00079-y) contains supplementary material, which is available to authorized users. * Francesca Ugolini f.ugolini@ibimet.cnr.it 1 Department of Natural resources and agricultural engineering, Faculty of Agriculture, Damanhour University, P.O. Box 59, Damanhour, Egypt 2 Institute of BioEconomy – National Research Council – Madonna del Piano 10, 50019 Sesto Fiorentino, Italy Journal of Soil Science and Plant Nutrition https://doi.org/10.1007/s42729-019-00079-y