# Thermoregulation and Soil Moisture Management in Strawberry Cultivation Munched with Sheep Wool
## 4 Discussion
Later, after several weeks of mulch exposure to atmospheric conditions, the natural contaminants and the waxy coating are removed, and the cuticle is partially degraded. Then, water molecules' access into the fibres' inner parts is facilitated, and quick wetting of mulch is possible. Other mulching materials, straw and bark, are naturally hygroscopic and easily wetted by liquid water after spreading them on the field. Water transport through the mulch layer is governed by the geometric configuration of its porous structure [35; 36]. Due to small fibre diameters and wool's natural tendency to interlock, the wool fibre network is much denser, and the pores between fibres are much smaller. In this case, water transport through the fibre assembly is more complicated and is driven mainly by capillary forces. For straw and bark, the pores inside the mulch layer are larger, so water can be transported easily through the mulch to the soil's surface. The mulching materials possess various water absorption capacities. Wool immersed or sprayed with liquid water absorbs large amounts of water, several times its weight. The wool absorbency is comparable to bark [37] and several times higher than that of straw [38]. For wool, the water is absorbed in the space between the fibres, where the air trapped in the pores is displaced with liquid water. Additionally, water molecules diffuse across the hydrophobic cuticle and are absorbed in the amorphous matrix surrounding the intermediate filaments in the inner cortical cells. Due to the keratin structure, built mainly from the proteins rich in hydrophilic groups located in the side and main chains, the water molecules are readily attracted. During rain, falling drops first wet the mulching material. Then, part of the water is absorbed inside the mulch material, while the rest is transported through the mulch layer to the soil surface. During heavy rainfall, the amount of falling water exceeds much absorption capacity. Thus, water not absorbed in the mulch seeps into the soil, quickly raising the soil moisture to a high value. As a result, immediately after heavy rain, for all mulched and unmulched plots, the soil moisture in its subsurface layer is almost the same, independent of the presence and kind of mulch material. After rain during dry days, water evaporates from the soil's surface, gradually decreasing the soil moisture. Solar radiation and blowing wind cause evaporation relatively quickly in soil not covered with mulch. For plots covered with mulch, the evaporation is less intense, and the soil moisture decreases much slower. The decrease in soil moisture occurs the slowest in plots mulched with wool. As mentioned above, water transport through the mulch layer occurs slowly. Moreover, wool mulch has an excellent water retention capacity and, on rainy days, absorbs a large amount of rainwater. The water molecules attached to the numerous inner hydrophilic groups of the keratin are hard to remove. Then, the water is slowly released, giving the soil higher humidity for longer. In this way, the wool assures good conditions for plant growth on dry summer days and ensures a favourable environment for soil microbiological activity. In contrast to straw and bark, wool mulch maintained its properties for several months over a period longer than one growing season. The remarkable durability of wool mulch results from the high resistance of wool to biodegradation. Due to the proteins' compact and highly crosslinked structure, wool biodegradation occurs slowly, much slower than for cellulosic-based straw and bark. The first external signs of biodegradation were detected in the layer adjacent to the soil several months after the spreading of mulch in the field. Biodegradation is caused by fungi that are naturally present in the environment. The fungi colonised the wool fibre surface and then, in the moist environment of the mulch, were easily reproduced.