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Air pollution is a major factor affecting human life and living quality in arid and semiarid regions. This study was conducted in the Al-Ahsa district in the Eastern part of Saudi Arabia to measure carbon dioxide (CO2) concentration over different land-use types. Initially, the study’s land use/land cover (LULC) was classified using the spectral characteristics of Landsat-8 data. Then, sensors were placed in five sites of different LULC types to detect CO2, air temperature, and relative humidity. The Friedman test was used to compare CO2 concentration among the five sites. Five LULC types were identified over the study area: date palm, cropland, bare land, urban land, and water. The results indicated that CO2 concentration showed a maximum mean value of 577 ppm recorded from a site dominated by urban lands. During the peak time of human transportation, a maximum value of 659 ppm was detected. The CO2 concentration mean values detected for the other LULC types showed 535, 515, and 484 ppm for the bare land, cropland, and date palm, respectively. This study’s sensors and procedures helped provide information over relatively small areas. However, modelling CO2 fluctuations with time for LULC changes might improve management and sustainability.

Considerable amounts of irrigation water of vegetable crops grown in homogenous sandy soil profiles could be subjected to deep percolation water losses due to inappropriately designed surface or subsurface drip irrigation methods. This study aimed to investigate the combined influence of implementing clay soil layer in homogenous sandy soil profile of low-tech greenhouse ridges and using modified surface drip irrigation (M-DI) on soil moisture distribution and water productivity of tomatoes. In the greenhouse, a 7.5 cm thick clay soil layer was implemented 15 cm from the soil surface of each ridge as a hydraulic barrier. Three irrigation regimes (100%, 70% and 50% of ETo) were imposed with the M-DI on tomato plants and 100%ETo with surface drip irrigation (DI) as control. Regarding economic valuation, viability was preserved for the M-DI and DI methods. The outcome indicated that soil moisture spreads more horizontally than vertically on the sandy soil above the clay soil layer. The combined effect of the homogenous sandy soil profile amendment and full irrigation (100%ETo) with the M-DI irrigation method increased the tomato fruit yield by 64.5%. Furthermore, the combined influence enhanced water productivity by the M-DI to 54.7 kg/m3 compared to 32 kg/m3 by the DI. However, M-DI demonstrated dominance over DI regarding returns, yield, and profit. Economic-wise, the M-DI requires 50% less of the lateral pipelines needed by the DI in low-tech greenhouses. Adopting the M-DI with a hydraulic barrier can improve soil moisture, water productivity, yield, and returns for tomato crops in low-tech greenhouses under sandy soil conditions. Also, the M-DI with the hydraulic clay barriers was an economically viable investment compared to the DI without clay barriers for growing tomatoes in low-tech greenhouses. [ABSTRACT FROM AUTHOR]

Water scarcity has necessitated the adoption of water-saving techniques in both protected and non-protected farming. This study aimed to evaluate the performance of a water-saving soilless cultivation technique and compare it to conventional soil-based cultivation in protected farming. The soilless technique utilized local gravel and a mixture of peat moss, humin-substrate, and perlite in a 4:3:1.5 ratio. During the tomato growth cycle, three irrigation regimes were imposed using drip irrigation: 8 Lh−1 design discharge (D1) emitters, 6 Lh−1 design discharge (D0.75) emitters, and 4 Lh−1 design discharge (D0.5) emitters for both cultivation methods. Vegetative growth, fruit yield, and water consumption were measured and water productivity was determined. Additionally, an economic assessment was conducted by estimating and comparing economic coefficients for both cultivation methods. Estimated coefficients included revenues, net profit, benefit–cost ratio, breakeven levels of production and prices, revenues over variable cost, and revenues on investment. The tomato fruit yield under soil-based cultivation surpassed the yield under soilless cultivation. Water productivity under soilless cultivation was nearly double (24.3 kg m−3) that of soil-based cultivation (15.5 kg m−3). Soilless cultivation saved 50% of the irrigation water applied by the conventional soil-based method, conserving energy and protecting the soil from deterioration. Revenues and net profits, driven by higher yield and lower variable costs, favored soil-based cultivation. The economic assessment demonstrated that both cultivation methods were economically viable. However, the soil-based cultivation method was more profitable due to its higher fruit yield. Overall, the results of this study suggest that the soilless cultivation technique is a feasible option for water-saving cultivation. However, the soil-based cultivation method remains more profitable due to its superior fruit yield. The soilless cultivation technique offers significant water savings but needs further improvements to achieve comparable economic returns to traditional farming. [ABSTRACT FROM AUTHOR]

Air pollution is a major factor affecting human life and living quality in arid and semiarid regions. This study was conducted in the Al-Ahsa district in the Eastern part of Saudi Arabia to measure carbon dioxide (CO2) concentration over different land-use types. Initially, the study's land use/land cover (LULC) was classified using the spectral characteristics of Landsat-8 data. Then, sensors were placed in five sites of different LULC types to detect CO2, air temperature, and relative humidity. The Friedman test was used to compare CO2 concentration among the five sites. Five LULC types were identified over the study area: date palm, cropland, bare land, urban land, and water. The results indicated that CO2 concentration showed a maximum mean value of 577 ppm recorded from a site dominated by urban lands. During the peak time of human transportation, a maximum value of 659 ppm was detected. The CO2 concentration mean values detected for the other LULC types showed 535, 515, and 484 ppm for the bare land, cropland, and date palm, respectively. This study's sensors and procedures helped provide information over relatively small areas. However, modelling CO2 fluctuations with time for LULC changes might improve management and sustainability. [ABSTRACT FROM AUTHOR]

The current study is aimed to assess water use efficiency and evaluate economic viability of hydroponic and conventional production of barley green fodder by keeping in view the water scarcity challenges in Saudi Arabia. A hydroponic system and open field experimental plot was used to evaluate the water use efficiency for different irrigation regimes. Economic indicators for both production systems are estimated and compared to accomplish economic assessment. Estimated indicators include returns from inputs and net profit; benefit-cost ratio; break-even levels of prices, production, and yield; returns over variable cost; and returns on investment. Results indicated that the yield of barley green fodder produced under hydroponic conditions overtopped the yield under conventional cultivation. Under hydroponic and conventional conditions, WUE was decreased with increasing the harvesting date. However, WUE for the hydroponic technique was much higher than the conventional one. The returns and net profits supported the conventional cultivation methods, where lower dry matter content coupled with higher fixed and variable costs incurred by the hydroponic technique outweighed returns leading to economic loss. Cost-benefit ratios, returns over investment, and break-even prices and yield suggested that growing barley fodder under the hydroponic technique is economically not suitable for small-scale farming. However, regarding water conservation, hydroponic barley cultivation showed superiority over conventional field cultivation. Further research on the adoption of hydroponic fodder cultivation is highly recommended for water-scarce arid regions, such as the Kingdom of Saudi Arabia. [ABSTRACT FROM AUTHOR]