Heavy metal (HM) contamination in soil poses a severe environmental threat, jeopardizing ecosystem health and potentially entering the food chain through plant uptake. Phytoremediation, a bioremediation technique utilizing plants to remove or immobilize contaminants, offers a sustainable and eco-friendly solution for HM remediation. This study investigated the interactive effects of arbuscular mycorrhizal fungi (AMF) and chelating agents (EDTA and DTPA) on the growth of maize (Zea mays L.) and alfalfa (Medicago sativa L.) cultivated in metal-contaminated soil and their impact on HM uptake by these plants. The findings revealed that AMF and chelating agents have complex interactive effects on plant growth and metal accumulation. Maize (Zea mays L.) shoot dry matter increased with AMF and chelating agents at lower concentrations. Both plants generally showed a significant (p ≤ 0.05) increase in shoot dry matter with amendments, with AMF × EDTA (10 mmol/kg) being the most effective for alfalfa. DTPA and EDTA generally reduced the DTPA-extractable metals in soil, suggesting potential for metal removal. However, the effects of AMF on metal availability were variable. Metal concentrations in maize (Zea mays L.) shoots increased with increasing DTPA and EDTA concentrations, while the effects of AMF were more complex. The alfalfa shoot metal content showed varied responses, with EDTA (5 mmol/kg) effectively reducing the metal uptake. In general, treatments involving chelating agents (DTPA and EDTA) tend to result in higher bioaccumulation factor (BF) values compared to the non-treated controls for most HMs in both plant species. Mycorrhizal fungi (AMF) treatment alone or in combination with chelating agents also showed that varied effects on HM uptake in both the alfalfa and maize treatments with chelating agents, especially at higher concentrations, generally promoted the greater translocation of HMs in both plant species. Both alfalfa and maize responded differently to treatments, with some treatments showing higher translocation factor (TF) values for certain HMs in one species compared to the other. Mycorrhizal fungi (AMF) treatment alone or in combination with chelating agents also showed varied effects on HM uptake and translocation in both alfalfa and maize. Further research is required to optimize remediation strategies that balance plant health and metal mobilization.

The composting of organic waste is a sustainable strategy for waste management and soil fertility improvement. However, the composting process is often associated with greenhouse gas (GHG) emissions, having a negative impact on the environment. This study investigated the effects of BC pyrolysis temperature (300 °C, 600 °C) and application rate (5% and 10%) on GHG emissions during the thermophilic phase and compost quality. The experimental treatments were a control and four BC treatments varying in pyrolysis temperature (300 °C, 600 °C) and application rate (5%, 10%). As a result, BC pyrolyzed at 600 °C and added at 10% (T2R2) resulted in the highest thermophilic temperature (63.5 ± 0.5 °C). This treatment significantly achieved substantial reductions in NH₃, N₂O, CH₄, and CO₂ emissions by 55 ± 2.7%, 50 ± 2.7%, 88 ± 4.2%, and 23 ± 2.3%, respectively, relative to the control. Compost quality was enhanced notably, with dry matter increasing to 46.4 ± 0.11% (T2R1), organic matter reaching 30.9 ± 0.05% in T2R1, and total nitrogen peaking at 0.8 ± 0.001% (T1R2). The C:N ratio decreased from 27:1 in the control to 21:1 in the treatment of T1R2, indicating an accelerated composting process. The NH₄-N levels were the highest in T1R2 and T2R2 (659 ± 0.1 and 416 ± 0.2 mg kg⁻¹), while EC increased to 9.5 ± 0.006 ms/cm (T2R1), and bulk density decreased to 410 ± 0.08 kg/m³ (T1R1). These results demonstrate that high-temperature biochar, especially at a rate of 10%, is effective in reducing emissions and improving compost quality. Future research should explore long-term effects and microbial mechanisms to optimize biochar use in composting systems.

This study investigated the effects of applying olive mill wastewater (OMWW) at different periods prior to corn (Zea mays) sowing on germination rate (GR), growth, and soil nutrient availability in calcareous soil. The OMWW was applied at rates of 0, 20, 40, and 60 m³ ha⁻¹ and was allowed to remain in soil for zero, one, two, three, or four months before sowing corn seeds. Immediate planting after OMWW application significantly reduced the GR, with rates of 83%, 75%, and 63% at 20, 40, and 60 m³ ha⁻¹, respectively. Germination improved when corn was sown one month after OMWW application, with a GR of 92% at both 20 and 40 m³ ha⁻¹ and 79% at 60 m³ ha⁻¹. The GR increased to 96% for the 40 and 60 m³ ha⁻¹ rates when OMWW was applied two months before planting. The adverse impact on GR disappeared when OMWW was in the soil for three months before sowing, providing a GR similar to the unamended control. Corn dry matter yield also improved when OMWW was applied two to three months before planting. The phytotoxic effects of OMWW, due to its high polyphenol content, diminished over time due to rapid degradation in calcareous soils. Soil available N and P were highest, and plant N, P, and K content increased, when OMWW was applied two months prior to planting. Soil pH decreased from 7.8 to 7.2 at 60 m³ ha⁻¹ of OMWW at planting time. Results suggest that OMWW can enhance soil quality and corn growth if applied one to two months before planting to avoid possible negative impact on germination. This work bridges the gap between waste management and sustainable agriculture, offering practical guidelines for OMWW utilization.

The systematic identification of appropriate sites for different rainwater harvesting (RWH) structures may contribute to better success of crop production in such areas. One approach to improving crop yields in North Kordofan, Sudan, that is mostly adaptable to the changing climate is in-field water harvesting. The main objective of this study is to employ a geographical information system (GIS) in order to identify the most suitable sites for setting in situ water harvesting structures, aiming to address climate change in this area. A GIS-based model was developed to generate suitability maps for in situ RWH using multi-criteria evaluation. Five suitability criteria (soil texture, runoff depth, rainfall surplus, land cover, and slope) were identified; then, five suitability levels were set for each criterion (excellent, good, moderate, poor, and unsuitable). Weights were assigned to the criteria based on their relative importance for RWH using the analytical hierarchy process (AHP). Using QGIS 2.6.1 and ArcGIS 10.2.2 software, all criterion maps and suitability maps were prepared. The obtained suitability map for the entire region showed that 40% of the region area fell within the “good” class, representing 7419.18 km², whereas 26% of the area was “excellent”, occupying 4863.75 km². However, only 8.9% and 15.6% of the entire region’s area were “poor” and “unsuitable” for RWH, respectively. The suitability map of the delineated pilot areas selected according to the attained FAO data revealed that one location, Wad_Albaga, was found to be in an excellent position, covering an area of 787.811 km², which represents 42.94% of the total area. In contrast, the Algabal location had 6.4% of its area classified as poor and the remaining portion classified as excellent. According to the findings from the validated trial, Wad_Albaga is located in a good site covering 844 km², representing 46.04%, while Algabal is classified as a moderate site, covering 341 km² or 18.6% of the area. This study concluded that the validation of the existing trial closely matched the suitability map derived using FAO data. However, ground data from field experiments provided more accurate results compared to the FAO suitability map. This study also concluded that using GIS is a time-saving and effective tool for identifying suitable sites and discovering the most appropriate locations for rainwater harvesting (RWH).

The sustainable management of olive pomace (OP) residues remains a major environmental challenge, requiring integrated strategies that enhance resource recovery while minimizing environmental impacts. This study evaluated the effects of OP-derived biochar (BC) produced at two pyrolysis temperatures (300 and 600 °C) and applied at two rates (5 and 10%, w/w) on composting performance and the physicochemical, biological, and nutrient characteristics of OP compost. Composting was initiated in a pilot-scale forced-aeration bioreactor to accelerate the decomposition of the composting mixture, after which the materials were transferred to indoor piles to complete the composting and maturation process. Two-way ANOVA showed that both BC pyrolysis temperature and application rate significantly affected several compost quality attributes, although their relative influence varied among the measured properties. The observed responses were consistent with differences in the physicochemical characteristics of the OP-derived BC resulting from the pyrolysis conditions. Compared with BC produced at 300 °C, BC produced at 600 °C significantly reduced moisture content (MC) from 17.81 to 11.44%, decreased bulk density (BD) from 0.69 to 0.52 g cm⁻³, increased organic matter (OM) from 70.61 to 82.78%, and raised compost pH from 7.67 to 8.43 (p < 0.001), and reduced microbial respiration from 2.00 to 1.60 CO₂ g⁻¹ OM day⁻¹ (p = 0.0270). Increasing the BC application rate from 5 to 10% significantly enhanced nitrogen (N) (1.64–1.79%), phosphorus (P) (0.57–0.67%), ammonium (NH₄⁺) (162–214 mg kg⁻¹), nitrate (NO₃⁻) (42.98–52.42 mg kg⁻¹), sulfur (S) (0.35–0.39%), and compost stability index (SI). Overall, the higher BC application rate, particularly when combined with BC produced at 600 °C, generally resulted in the most favourable compost characteristics, although several responses were statistically comparable with those obtained using BC produced at 300 °C and applied at 10%. Germination indices of 97.5–135.8% indicated that the final composts exhibited low phytotoxicity and generally mature. These findings indicate that integrating OP-derived BC into OP composting can improve the quality and stability of the resulting compost while providing an integrated strategy for the valorization of within circular bioeconomy approach.

Phosphorus (P) is an essential macronutrient, but its limited availability in calcareous soils remains a major constraint to crop nutrition. Treated wastewater (TWW) offers a sustainable irrigation source in arid regions, enhancing water supply and contributing nutrients such as P. This study evaluates the effects of TWW and tap water (TW) irrigation, combined with varying rates of phosphorus fertilizers, such as single superphosphate (SSP) and diammonium phosphate (DAP), on maize (Zea mays L.) growth, nutrient uptake, and soil properties. A greenhouse experiment was conducted using maize grown in sandy calcareous soil. TWW irrigation with SSP (40 kg/ha) and DAP (20 kg/ha) resulted in the highest shoot dry matter (2.6 g), while TW with DAP at 20 kg/ha produced 2.2 g. Root biomass was generally higher, peaking at 8.3 g under TWW-SSP (40 kg/ha) and 5.7 g under TW-SSP (40 kg/ha). Nitrogen uptake was highest under TWW, with TWW-DAP (40 kg/ha) yielding the highest N content in shoots (1.9%) and roots (1.2%). Phosphorus content peaked at TWW-DAP (30 kg/ha) in shoots (0.52%) and roots (0.26%). Potassium uptake also improved with TWW, particularly in shoots (4.5%) under TWW-SSP (40 kg/ha) and roots (2.6%) under TWW-DAP (40 kg/ha). Post-harvest soil analysis showed TWW maintained stable EC (0.3–0.5 dS/m) and neutral pH (7.6–7.8). Higher DAP rates (40 kg/ha) with TWW increased soil organic matter, nitrogen (266.2 mg/kg), phosphorus (38.0 mg/kg), and potassium (385.3 mg/kg). In contrast, TW irrigation had lower nutrient enhancement, though high DAP rates still improved soil fertility. These findings highlight the potential of integrating TWW with phosphorus fertilizers to improve crop performance and soil fertility in calcareous soils. This approach offers a sustainable alternative to conventional practices, supporting sustainable crop production in water-limited environments. Further long-term studies are recommended to assess the sustainability of TWW irrigation in arid soils.