5 Uses for the Mighty Woodchip
As you would expect, the hotter and drier your climate, the greater the benefit is likely to be.
Plastic mulches give the same, if not greater, water retention but can create other problems. Solid films create an anaerobic environment under the mulch, which can lead to compacted and lifeless soil. Even the woven mulches, which do allow infiltration and some breathability, are not as good as an organic material for healthy soil. In wet climates slugs and snails can proliferate under plastic mulches where they have a safe, moist home away from most predators.
MODERATING SOIL TEMPERATURE
Using a mulch of any sort can help to warm cold soils and cool hot ones. The mulch gives protection to soil and plant roots, shielding it from extremes. It acts as winter coat, sunscreen lotion and umbrella combined.
As with water retention, there have been numerous studies looking at the effects of mulch on temperature. In many situations, plastic mulches will give higher temperature differences than organic materials. However, what I intend to illustrate in this book is that when looking at the multiple benefits a woodchip mulch gives you, it is worth sacrificing a little on water retention and temperature to get the long-term soil health benefits of woodchip mulches.
PHYSICAL DAMAGE
Bare soil is vulnerable soil. Mulching protects soil from physical damage such as heavy rain or wind, and in extreme weather conditions also helps to stop soil being washed or blown away. Woodchip mulches allow water to gently percolate through to the soil, whereas solid plastic mulches prevent the water from reaching the soil, instead causing localised flooding issues as the rain runs off the plastic. Wood-chip mulch even helps reduce damage from compaction caused by us walking or driving over the soil. The mulch cushions and absorbs our impact and keeps the soil in good condition underneath.
PEST AND DISEASES
Woodchip mulches have the potential to reduce some pests and diseases. Applied at the right time, they can cover over fungal spores on the soil and prevent them spreading when rain splashes back up onto the plant leaves. The mulch from some tree species will deter pests; for instance, cedar chip can help to keep termites and beetles away. New research in the UK has also been looking at using the salicylic acid in willow woodchip to stimulate an immune response in apples to help prevent scab.