Aerobic composting is a cost-effective option for managing sewage sludge and organic waste. The performance of aerobic composting of sludge mixed with locally available organic materials was evaluated under protected, non-temperature-controlled conditions, and potential management options for the resulting products were assessed. Three mixtures were evaluated in two separate runs: sludge and olive mill pomace (1S:1J), sludge with olive mill pomace, manure, and plant waste (3S:3J:2M:2W), and sludge with manure (1S:1M). Pile temperatures reached only 30–40 °C and did not attain the thermophilic range required for reliable sanitization. From the initial to final sampling, organic matter decreased by 5.2–29.8% in the first run and 25.0–42.9% in the second run. Nitrogen changed by +31.1% to +200.8% in the first run and −51.8% to +48.9% in the second run. Phosphorus changed by +80.2% to +217.5% in the first run and −33.0% to +81.9% in the second run. Selected trace elements also showed treatment-specific numerical changes, including a 131.1% increase in Fe and a 72.6% decrease in Zn in 1S:1M during the first run. All measured potentially toxic elements remained below the cited regulatory limits. Microbiological compliance varied by treatment and run, and one second-run mixture contained 9.4 × 10³ MPN/g total fecal coliforms, above the reported Class 1 limit. These results show useful nutrient characteristics but do not demonstrate consistent sanitization or unrestricted agricultural suitability. Additional process control and microbiological verification are required before reuse.

Efficient nutrient management through fertigation is essential for sustaining table grape production under water-limited Mediterranean environments. This study evaluated the effects of graded potassium (K) fertigation rates on yield and berry quality of grapevines under semi-arid conditions in northern Jordan. Field experiments were conducted over three consecutive seasons at three locations using four potassium application rates (0, 100, 200, and 300 kg K₂O ha⁻¹) applied through drip fertigation and synchronized with key vine phenological stages. Yield and fruit-quality parameters were analyzed using linear mixed-effects models accounting for treatment, year, location, and their interactions. Potassium fertigation significantly increased total yield, cluster weight, and berry physical attributes, including firmness, volume, weight, and diameter, whereas total soluble solids (TSS) and juice pH were largely unaffected. Relative to the control, potassium fertigation progressively increased total yield per vine by approximately 21%, 47%, and 72% under the 100, 200, and 300 kg K₂O ha⁻¹ treatments, respectively, although the magnitude of response differed among locations and growing seasons. Significant treatment × location interactions indicated that site-specific soil conditions influenced potassium response. These results demonstrate that synchronizing potassium supply with vine phenological demand through fertigation enhances productivity and berry physical quality without compromising fruit chemical composition. The observed improvements are consistent with the established physiological roles of potassium in osmotic regulation, assimilate transport, and berry development, supporting optimized potassium fertigation as a key component of precision nutrient management for sustainable viticulture in semi-arid Mediterranean regions.