Mulching

A mulch is a layer of material applied to the surface of the soil and its purpose is to conserve moisture, improve the fertility and health of the soil, reduce weed growth, and enhance the visual appeal of the area.

It is typically made from plant materials such as leaves, grass, twigs, crop residues, straw, and other organic substances like bark, wood chips, grape pulp, shell nuts, green waste, leftover crops, compost, and manure. Mulching is a key practice in both commercial crop production and gardening and can dramatically improve the soil’s ability to store water.

Mulching as sponge measure involves using organic material to cover the surface of bare soil or existing plants. Materials like manure or compost are naturally incorporated into the soil by the activity of worms and other organisms, further enriching the soil as they decompose. 

The benefits of mulching include:

• Protection: It shields the soil from wind and water erosion, preventing the loss of soil particles.
• Improved water infiltration: It helps maintain a good soil structure by keeping pores open and preventing crust formation, which allows rain and irrigation water to infiltrate effectively.
• Moisture retention: By reducing evaporation, mulch keeps the soil moist, thus reducing the need for irrigation and allowing plants to make better use of available rain, especially in dry areas or seasons.
• Soil organism support: Organic mulches provide food and suitable conditions for soil organisms, including earthworms, fostering soil health.
• Weed suppression: A sufficient mulch layer makes it difficult for weeds to grow by blocking their access to sunlight.
• Temperature regulation: Mulch acts as a shade, keeping the soil cool and preventing overheating while retaining moisture.
• Nutrient release: As mulch decomposes, it continuously releases nutrients into the soil, thereby fertilizing crops.

Recent studies have found that increasing mulch density generally leads to improvements in both water retention and absorption. Higher mulch densities result in more significant increases in water retention and absorption compared to lower densities, making it an effective strategy for improving soil moisture management.

Natural mulching with dry plant residues is now an established practice in olive growing, as in other tree crops. It is carried out extensively over the entire cultivated area and is therefore considered a genuine cultivation practice. In olive growing, in particular, pruning residues are left on the ground and then mechanically shredded together with the grass layer to form a uniform cover that reduces evaporative erosion and enriches the soil with organic matter.