Introduction: Previous studies showed that biochar amended soils significantly enhanced the growth and yield of quinoa under water limitations. So it becomes an emerging agronomic strategy to consider for sustainable quinoa production. Biochar can specifically be considered for the area particularly receiving low annual rainfall and more vulnerable to current climate change conditions.Materials and Methods: A field experiment was conducted using the quinoa variety INIA 415 Pasankalla, employing a factorial design to assess the effects of different application rates of biochar made of municipal pruning waste and agricultural waste (0, 1, 2, and 3 t·ha⁻¹), and three irrigation intervals (irrigation every 5 days, irrigation every 10 days, and irrigation every 15 days). The volumetric soil moisture content, the soil hydraulic properties, and quinoa's biometric characteristics and yield components were evaluated.Results: The results indicated that the longest irrigation intervals (10 and 15 days) resulted in soil moisture levels between 19% and 40% below the wilting point (soil matric potential: −1.5 MPa), creating water stress conditions. However, biochar application increased the field capacity from 0.31 to 0.38 g H₂O g⁻¹ soil, raised soil air content from 22% to 29% at irrigation, and promoted the quinoa's soil water absorption below the wilting point. Furthermore, the application of 3 t·ha⁻¹ of biochar significantly enhanced quinoa yield, increasing it from 3.18 to 4.22 t·ha⁻¹, along with improvements in leaf area, total biomass, root length, and panicle length by 70.74%, 76.54%, 14.34%, and 16.55%, respectively.Conclusions: It was concluded that a 3 t·ha⁻¹ biochar application mitigated the negative effects of water stress caused by prolonged irrigation intervals. This biochar treatment improved the soil's physical properties and enabled the quinoa variety INIA 415 Pasankalla to achieve yields close to its theoretical productive potential.

Biochar and beneficial microorganisms have gained increasing attention as alternatives for improving soil properties and crop performance under sustainable agricultural systems. Wheat (Triticum aestivum L.), one of the major crops in the Andean region, requires management strategies that enhance productivity while improving soil quality. This study evaluated the effects of biochar from the native high-Andean grass Festuca glyceriantha Pilger, Trichoderma harzianum, and their combination (Trichoderma harzianum immobilized on biochar) on the growth, yield, grain protein, and soil organic carbon (SOC) storage of wheat (Triticum aestivum L.) in Ayacucho, Peru. A 2 × 2 factorial randomized complete block design with four replicates was used (biochar rate: 0.96 t ha⁻¹). Colonization of biochar by Trichoderma harzianum yielded 5 × 10⁸ spores mL⁻¹ in the recovered suspension, supporting its use as a microbial carrier. Both inputs improved root length, plant height, and biomass accumulation, with responses varying across phenological stages. Grain yield exceeded the control (1.86 t ha⁻¹) by 32.26% with biochar (2.46 t ha⁻¹), 17.74% with Trichoderma harzianum (2.19 t ha⁻¹), and 30.11% with both (2.42 t ha⁻¹). The combination did not outperform biochar alone. The significant biochar × Trichoderma harzianum interaction (yield, p = 0.03; grains per spike, p = 0.02) cannot be interpreted as biological antagonism because inoculum dose and delivery method were not equivalent between treatments (two drench applications in T03 vs. a single application of colonized biochar in the sowing furrow in T04), and the significant biochar × Trichoderma harzianum interaction (yield, p = 0.03; grains per spike, p = 0.02) reflected a less-than-additive response. Trichoderma harzianum increased grain protein content (p < 0.01), whereas biochar did not (p = 0.90); thousand-grain weight and chlorophyll content were unaffected. SOC storage did not differ among treatments (p = 0.101; 156.5–228.4 Mg C ha⁻¹), so no carbon sequestration benefit can be concluded after one growing season. Biochar mainly enhanced grain yield, whereas Trichoderma harzianum mainly improved grain protein. These results support applying each input independently according to the agronomic objective, pending multi-season and multi-site validation with equivalent inoculum doses and complete control treatments.

Efficient water management in agriculture is key to the sustainability of crops in inter-Andean valleys (IAV), where water availability is at risk due to climate change (CC). Quinoa, as a strategic crop in these ecosystems, requires a detailed analysis of its water use to optimize its production without compromising water resources. This study quantified the water footprint (WF) (green, blue and grey) of three quinoa varieties (INIA 415 Pasankalla, INIA 420-Negra Collana and INIA 441-Señor del Huerto) harvested in a sandy loam soil in an IAV of Peru. In addition, the trend of the WF in 12 agricultural seasons was evaluated, and future climate scenarios (SSP1-2.6, SSP3-7.0 and SSP5-8.5) were projected to estimate the impact of CC on the crop's water demand towards 2090–2100. The results showed significant differences in water-use efficiency among varieties. INIA 441-Señor del Huerto showed the highest water efficiency, with a 3.20 t ha⁻¹ yield and a low total WF, making it more sustainable under CC conditions. In contrast, INIA 420-Negra Collana had a higher water demand, making it less viable under water-stress scenarios. Climate projections indicate an increase in water demand for quinoa under scenarios of greater radiative forcing, which underscores the need to develop water management strategies. These findings highlight the importance of selecting more efficient varieties for water use and adopting sustainable practices to mitigate the effects of climate change on quinoa production at IAV.