Houda Oueriemmi

Climate change and soil degradation threaten agricultural sustainability in arid oases, where water and nutrient limitations constrain crop production. In Tunisia, date palm residues are abundant but frequently burned despite their potential as soil amendme. This study assessed the effects of date palm waste biochar (B; 10 t ha⁻¹), mineral fertilizers (NPK), and their combination as enriched biochar (BNPK) on soil fertility, including total organic carbon (TOC) and total nitrogen (TN), as well as barley (Hordeum vulgare L.) yield over two consecutive cropping seasons (2023–2024) using a randomized complete block design with three replications. During 2024, B increased TOC to 0.5% (control: 0.18%), while NPK enhanced TN to 0.037% in 2023; however, in 2024, nitrogen levels returned to values comparable to the control condition (0.017%). BNPK combined these beneficial improvements, maintained them in 2024, and resulted in a C/N ratio of 16.7 (control: 9.6), reflecting the most favorable balance between soil carbon accumulation and nitrogen retention. Grain yield increased by 21% (B), 80% (NPK), and 79% (BNPK) relative to the control (3.12 t ha⁻¹), while BNPK reduced soluble sugars in grains (fructose 100%), glucose 86% (control: 0.09, 0.014) and increased grain nitrogen content to 1.80% (control: 0.74). Principal component analysis revealed a clear separation among treatments, with BNPK strongly associated with improved soil fertility, grain yield, and grain quality. These results demonstrate that integrating biochar with nutrient management enhances soil fertility and supports sustainable agriculture in arid oasis agroecosystems.

Background: Soil salinity poses a significant threat to agricultural lands by adversely affecting soil properties, crop productivity, and, consequently, global food security. This study evaluated the effects of date palm waste compost (C), applied alone or combined with biochar (BCC) or Ramial chipped wood (RCWC), on soil properties and barley yield under arid and saline conditions. Methods: A field experiment was performed in a completely random design with three replications. In addition to the unamended soil (control), treatments with compost (C), biochar + compost (BCC) and Ramial chipped wood + compost (RCWC) were tested. We monitored soil physico-chemical parameters, straw biomass, grain yield, and soluble sugar levels over two crop seasons. Results: All treatments enhanced soil fertility. However, the sodium adsorption ratio (SAR) and the cation ratio of soil structural stability (CROSS) increased in soils amended with compost alone in the second crop year. Barley (Hordeum vulgare L.) cultivated in soil amended with C and BCC produced 28% and 37% more dry biomass, respectively, in the second year, while no significant effects were observed in the first year. This may be attributed to the higher availability of nutrient content (N and P) in soils during the second year. In the first year, plants amended with BCC exhibited the highest accumulation of sucrose and fructose, with increases of up to 39% and 66%, respectively. Conclusions: Compost application did not affect barley yield during the first crop year, highlighting limited effects on soil fertility. However, C and BCC improved barley yield in the second year after application. No synergistic effect was observed between biochar, Ramial chipped wood, and compost. Future Perspective: Further studies should focus on the long-term effects of organic soil management, including salinity issues, to support sustainable agriculture in arid regions.