The Use of Wood Fiber for Reducing Risks of Hydrophobicity in Peat-Based Substrates

Brian E. Jackson,Jean-Charles Michel,Stan Durand,William C. Fonteno

doi:10.3390/agronomy11050907

Abstract

Peat substrates are well known to become hydrophobic during desiccation, thus degrading their water retention properties. Synthetic wetting agents are commonly incorporated to limit the risk of hydrophobicity, but substrates companies are searching for more sustainable alternatives. To that end, the effect of wood fiber addition in peat-based mixes was measured using contact angles and hydration curves. The study was carried out on two raw materials (white milled peat and wood fiber) and binary mixes. The results showed a shift from hydrophilic to more hydrophobic character with a decrease in the ability to rewet of peat-based substrates in relation to the intensity of drying, whereas wood fiber remained hydrophilic. Increasing wood fiber content in peat-based mixes improved the rehydration efficiency, but with a lower intensity of that measured with synthetic wetting agent addition. Our results highlighted the hydrophilic nature of wood fiber and demonstrated an additional benefit of wood fiber use in peat-based growing media.

Highlights

Peats are by far the most widely used components of horticultural substrates [1], mainly due to their physical properties
Emerging works are looking for organic alternatives to synthetic wetting agent used for reducing the risks of peat hydrophobicity occurring during its drying, by promoting mixes with both complementary and more hydrophilic peat alternatives
This rate was defined in order to maintain a same dry bulk density (BD) for a material, whatever its initial Moisture contents (MC) (40%, 50%, and 60% w/w), in order to be able to compare the water capture depending on these different initial MC

Summary

Introduction

Peats are by far the most widely used components of horticultural substrates [1], mainly due to their physical properties Their sources of supply are very important worldwide, with a not very prohibitive cost. Substrate companies are seeking to reduce peat content in their recipes by incorporating more renewable organic materials with a lower carbon footprint, while maintaining or even improving the agronomic qualities of substrates. These mixes usually aim to increase the air-filled porosity (AFP) of peat-based growing media using peat substitutes with coarser porosity. Emerging works are looking for organic alternatives to synthetic wetting agent used for reducing the risks of peat hydrophobicity occurring during its drying, by promoting mixes with both complementary and more hydrophilic peat alternatives

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Discussion

Conclusion