Assessment of Two Sheep Wool Residues from Textile Industry as Organic Fertilizer in Sunflower and Maize Cultivation

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.