Resource mismanagement in most arid parts of the world is alarming. In these areas, harsh climatic conditions such as very high temperature, low rainfall, and strong wind are common. Additionally, they are characterized by the presence of salt-affected soils and lack of fresh water. The present study aims at characterizing and classifying the soils that occur in the arid conditions of Abu Dhabi Emirate and to identify its relation with the arid and semiarid conditions. The United States Department of Agriculture system of soil classification (USDA Soil Taxonomy) and the World Reference Base for Soil Resources (FAO Classification System) were used for comparison between soil classifications using both systems. Landsat-7 ETM image (Enhanced Thematic Mapper) acquired in 2002 and Geographic Information Systems has been used for the compilation and production of maps. The main physical and chemical characteristics of each map unit were determined and stored in the geographical database. The results reveal that the uniform-looking landscape of Abu Dhabi coastline presents a diversity of subsurface features and horizons that enable categorization of soils into different soil types. A soil map at a scale of 1:50,000 has been produced, the map units are mostly consociations with some associations and very few complexes. The present study highlights factors and processes responsible for soil formation. The study shows a very high similarity between the soils that occur in the arid conditions of Abu Dhabi and soils that occur under the same conditions of the world. USDA Soil Taxonomy proved to be well suited and more appropriate for classifying soils of arid conditions.

The present study examines the role of leguminous compost (LC), humic acids (HA), and phosphate-solubilizing bacteria (P-SB) in alleviating the stress effects of high soil CaCO₃ content in Phaseolus vulgaris. Two pot trials for two consecutive seasons; fall 2019 and summer 2020 were implemented in an open greenhouse. A mixed three-way ANOVA, two independent factors (season and soil treatments) and one within factors (time) were used with four replicates. Residual maximum likelihood (REML) analysis was used for the mixed model of the studied traits. Inoculation of calcareous soil with P-SB (a 1:1 mixture of two Pseudomonas sp.; Ps. mallei and Ps. cepaceae) significantly exceeded LC, HA, or even LC+HA for the positive results obtained. P-SB facilitated nutrient solubility (e.g., N, K, Fe, and Mn), including conversion of insoluble phosphorous into a form available in the tested soil due to increased soil enzymatic activities (e.g., phosphatases and phytases). This mechanism, combined with a decrease in soil calcium carbonate content and an increase in cation exchange capacity (CEC) and organic matter (OM) content, increased the availability of various nutrients to plants, including P, in the soil, which contributed to the increased plant output. Adequate P content in plants led to a marked decrease in plant acid phosphatase activity under high content of CaCO₃. The study concluded that the use of P-SB promotes biological activities, nutrient availability, and thus the productivity of calcareous soils, enabling Phaseolus vulgaris plants to withstand stress produced by high CaCO₃ content through the development and/or adoption of potentially effective mechanisms. Strong highly significant interactions between the treatments and time were observed using the Wald’s statistics test, which indicates a positive correlation.

During the 2019 and 2020 seasons, nutrient-deficient virgin sandy soil was examined along with the investigation of the response of Phaseolus vulgaris plants to soil application with biocompost in integration with chemical fertilizers applied to soil and plants. Four treatments (100% of the recommended NPK fertilizer dose (control), 75% NPK applied to soil + 25% foliar spray, 75% NPK applied to soil + 25% foliar spray + leguminous compost (C_L), and 75% NPK applied to soil + 25% foliar spray + C_L containing Bacillus subtilis (biocompost; C_LB)) were applied in a randomized complete block design. The 75% NPK applied to soil + 25% foliar spray + C_LB was the best treatment, which exceeded other treatments in improving soil fertility and plant performance. It noticeably improved soil physicochemical properties, including available nutrients, activities of various soil enzymes (cellulase, invertase, urease, and catalase), soil cation exchange capacity, organic carbon content, and pH, as well as plant growth and productivity, and plant physiobiochemistry, including nutrients and water contents, and various antioxidant activities. The results of the 2020 season significantly outperformed those of the 2019 season, indicating the positive effects of biofertilizers as a strategy to combine soil supplementation with NPK fertilizers and allocate a portion of NPK fertilizers for foliar spraying of plants in nutrient-deficient sandy soils.