Investigating the effectiveness of stone and plant mulch on soil moisture storage in tree holes in the green belt of southern Mashhad

The location on the dry belt of the world and the recent droughts have doubled the need to increase water efficiency, especially in nature restoration projects, including the green belt projects of the country's big cities. Therefore, research and assessment to find ways to optimal the use of water and reduce the water requirement of the plants are among the essential needs of these areas. Based on this, the current research aims to evaluate the effectiveness of stone and pebble as well as plant residue mulches and on soil moisture retention in cultivation pits in the green belt of southern Mashhad. For this purpose, three irrigation treatments in three blocks with three treatments of stones and pebbles mulch, plant remains mulch, and the control in a total area of 1.5 ha with nine species (Celtis caucasica, Colutea buhesi, Contoneaster nummlaria, Kochia prostrata, Fraxinus excelsior, Morus alba, Cupressus sempervirance, Paliurus spina christi, Hypophae ramnoides) and four replications were cultivated in each block. Plots were irrigated with a specific plan and humidity and temperature of the soil, as well as the survival rate and growth of the cultivated species were regularly measured during the research. Then the effects of the used mulches on the storage of humidity and temperature and the establishment and growth of the plants were analyzed and investigated. The results showed that the treatment with stone mulch showed better growth in most of the species with a significant difference of 99%. Besides, there was a significant difference with other treatments in terms of moisture retention of the plant mulch in a few days after irrigation. Still, after these days stone mulch showed better performance on moisture retention. No significant difference was observed between the treatments in terms of plant survival. Finally, according to the obtained results and since stone mulch is preferred both in terms of preparation, implementation, and durability in the field, it can be said that stone mulch would be a better suggestion.