Wool and Hair Waste as Nutrient Source for High-value Crops

Abstract

<jats:p>One small-plotfield and five container experiments were conducted to evaluate sheep wool-wastes and human hair-wastes as soil amendments and nutrient sources for high-value crops. Overall, the wool-waste or hair-waste addition to soil: 1) increased yields from basil, garden sage, peppermint, valerian, thorn apple, marigold, foxglove, and swiss chard; 2) increased the amount of secondary metabolites (such as essential oils and alkaloids); 3) increased NH<jats:sub>4</jats:sub>-N and NO<jats:sub>3</jats:sub>-N in soil; 4) increased total N (and protein) content in plant tissue; 5) did not affect soil microbial biomass; and 6) decreased mycorrhizae colonization of plant roots. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analyses indicated that some of the wool and hair in soil from the container and field experiments (after two field seasons and several harvests) retained its original structure, retained a significant amount of S and some N, and was not fully decomposed. Our results indicate that single addition of wool or hair-waste of 0.33% by weight to soil would support two to five harvests or crops, without addition of other fertilizers, and may improve soil biological and chemical characteristics.</jats:p>

Market Potential for Specialty Compost Produced from Wool Waste

“…Wool acidifies soil, thus improving the pH for many garden and greenhouse crops, and it improves the water-holding capacity of soil in potted plants (Poston et al 2005) because of its hygroscopicity (Zoccola et al 2009). Wool also contains essential plant nutrients (Gershuny and Martin 2018), decomposes slowly, and acts as a slowrelease sulfur, nitrogen, phosphorous, and potassium fertilizer under field or greenhouse conditions (Zheljazkov et al 2005) and for potted plants (Poston et al 2005).…”

“…It has been suggested that the addition of wool at 3.3 gÁkg À1 of soil may support two to five harvests under greenhouse conditions and two to four seasons under field production conditions (Zheljazkov et al 2005). However, raw wool contains impurities such as detergents and pesticides (Pearson et al 2004) that could contaminate compost and soils (Fong et al 1951).…”

“…Wool is nonperishable and can be easily stored until there is a positive market; however, in some regions and at certain times, wool is not commercially viable because of the lack of demand and/or excess storage from previous harvests. Excess wool and waste wool are currently landfilled or discarded, possibly creating environmental challenges (Zheljazkov et al 2005). Therefore, an alternative market for wool needs to be identified.…”

“…On a national basis, the potential demand for compost is estimated to be an order of magnitude greater than the potential supply (Alexander et al 2022). There is a significant body of research available on the benefits of sewage sludge, animal manures, and crop residues in compost, but there has been limited research of the use of other organic wastes, such as wool waste, as a soil amendment and nutrient source for crops (Zheljazkov et al 2005). Disposal of keratin wastes, such as fiber byproducts from the wool textile industry and low-quality raw wools, represents a considerable environmental problem (Zoccola et al 2009).…”