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Smart Capillary Barrier (SCB) has been recently promoted to decrease soil salinity and improve water use efficiency and the sustainability of arid land agriculture. In this study, we investigated the effect of SCB on soil microbial diversity, enumeration, and respiration in a tomato field trial. SCB soil and control (unstructured homogenous soils, H) plots were irrigated with four levels of salinity (ECw = 0.8, 3, 6, and 9 dS m−1). Microbial diversity was assessed by ITS and 16S rRNA gene sequencing, enumeration of culturable heterotrophs by agar plates, and microbial respiration by MicroResp™ assays. Salinity was the main driver of the soil microbial diversity, showing a substantial reduction in the number of operational taxonomic units (− 8% for both bacteria and fungi), enumeration of culturable heterotrophs (− 51% for bacteria and − 53% for fungi), and respiration (− 18%) at 9 dS m−1 water salinity. Microbial community composition was significantly different between the SCB and H soils, as evidenced by multivariate analyses and by the appearance of 3352 unique operational taxonomic units at SCB samples that were absent in H plots. The SCB soil showed a steeper metabolic quotient increase in response to soil salinity than the H soils. The abundance of functional microbes such as nitrogen-fixing and nitrifying prokaryotes, as well as mycorrhiza, was also significantly increased in the SCB soils in comparison with the H soils. Our findings suggest that adopting SCB design leads to higher overall soil microbial biodiversity, including those communities unable to withstand extreme soil salinity conditions.

Aquaponics are efficient systems that associate aquatic organisms’ production and plants by recirculating water and nutrients between aquaculture and hydroponic tanks. In this study, we have characterised the bacterial communities in the fresh water aquaponics system that can mineralise polysaccharides and phytate by producing carbohydrate degrading enzymes and phytases, by 16S rRNA gene sequencing and in vitro culture techniques. Around 20% of the operational taxonomic units (OTUs) identified were previously reported to carry fibre-degrading enzymes putative genes, namely β-glucanase (1%), xylanase (5%) or cellulases (17%). Ten % of the OTUs were previously reported to carry putative genes of phytases with different catalytic mechanisms, namely β-propeller (6%), histidine acid phytases (3%) and protein tyrosine phytase (

In this study, we present an interactive problem-based learning environment, namely, the “Soil Skills” contest for final year students majoring in Soil Sciences, a BSc program at Sultan Qaboos University, Oman. This five-day component of a compulsory field-course exemplifies an active learning approach, which has been promoted by higher educators based on its efficacy and outcomes on the student’s learning processes. Our pedagogical strategy integrates the concepts and notions of: (i) Inquiry-Based Learning (IBL), (ii) scaffolding, (iii) teams competition and gaming, and (iv) Data–information–knowledge–wisdom. We evaluated outcome-based learning objectives of two cohorts (2018 and 2020) of Soil Sciences students during the contest via a field evaluation by juries, composed of Soil Science faculty, using an objective evaluation scheme. The evaluation of the contest was also done through a combination of an online questionnaire sent to registered students and peer-assessment among students conducted by the group leaders. The results of teaching evaluation of the course, in the semester when the contest was implemented, showed a higher rating score (3.93/4.0) than the college average (3.16/4.0) for all other courses (about 150/semester) and also than the average score (3.30/4.0) of the course in the previous year. The surveys of two cohorts showed that majority of the students indicated positive improvements in various transferable and interpersonal metacognitive skills (self-reported improvements in problem-solving abilities, thinking out of the box, observation, teamwork, capacity to perform under pressure, and communication). Further surveys of forthcoming cohorts are needed. The Soil Skills pedagogy approach is in line with the call towards enriching geoscience students with the skills and competencies necessary to address real-world problems of complex Earth systems.