Mulching
Quick answer. FAO states that in very hot climates mulching can reduce water loss from the soil and reduce soil temperature. Both are directly relevant here. FAO is equally direct about the constraint: mulching is difficult in these environments because of a shortage of organic matter. Mulch where you can, keep it clear of stems and trunks, and do not assume material will be available at the scale the technique implies.
What FAO actually claims for mulch
Three uses, stated plainly in the source. Soil protection. A nutrient source when mixed into the topsoil. And — specifically for very hot climates — reduction of water loss from the soil and reduction of soil temperature.
That last pair is why mulch matters more in Kuwait than in the temperate climates most gardening advice is written for. Reducing soil temperature protects the shallow roots that FAO's arid-soil profile is full of, and reducing evaporative loss addresses the almost always severe shortage of water that heads FAO's list of arid-soil problems.
The constraint, stated rather than skipped
FAO does not present mulching as straightforward here. It says mulching is difficult in these environments because of a shortage of organic matter, and adds that the application of organic substances is often limited by competitive use of crop residues for fodder, fuel and roofing. Advice that recommends deep mulching everywhere without acknowledging supply is advice written for somewhere else.
The practical consequence is prioritisation: mulch where the benefit is greatest — around newly planted trees, over shallow-rooted crops through the hottest period, in containers — rather than spreading a scarce resource thinly across everything.
Keep it off the stem
Mulch piled against a trunk or stem holds moisture against bark that is not adapted to it, and produces the same problem as planting too deep — with the additional irony that it is done by people trying to help. Leave a clear gap at the base. Mulch belongs over the root zone, not against the plant.
Mulch and nitrogen
A high-carbon mulch left on the surface breaks down slowly and has limited effect on soil nitrogen. The same material mixed into the topsoil behaves like immature compost and temporarily immobilises nitrogen. FAO mentions both uses; the distinction between surface mulch and incorporated material is the one to keep clear, because they have different consequences.
Check what a mulch is before applying it. Imported organic material can carry salinity, and in a region where FAO notes occasional excess of soluble salts, adsorbed sodium and boron, a mulch can add to a problem you are already managing. Mulch is also not a remedy for a plant in decline — if the cause is waterlogging, mulch that retains surface moisture makes it worse.
Sources
FAO — Fertilizer and Plant Nutrition Bulletin 16, Chapter 8 (mulching in dryland and very hot climates; soil protection; competitive use of residues), Chapter 5 (arid soils; poor structure — organic matter, mulches and amendments), Chapters 4 and 7. Accessed 27 August 2026. No depth, rate or quantity is stated.
Last reviewed 27 August 2026