An artificial soil structure includes at least one hydrophobic layer of hydrophobic particles provided in a soil. A particle size of the hydrophobic particles can be 2000 micrometers and less. The hydrophobic particles are sand and/or dirt treated with a water-repellent agent or hydrophobic particles having a high molecular weight polymer. An artificial water-retentive soil structure includes a soil block containing a water-retentive agent and a hydrophobic layer of hydrophobic particles provided on the soil block. A method of preventing land desertification includes the steps of placing a hydrophobic layer of hydrophobic particles in a soil at a prescribed depth from the earth surface and controlling the water content in said soil.