Amidst depleting water resources, rising crop water needs, changing climates, and soil fertility decline from inorganic modifications of soil, the need for sustainable agricultural solutions has been more pressing. The experimental work aimed to inspect the potential of organically activated biochar in improving soil physicochemical and nutrient status as well as improving biochemical and physiological processes, and optimizing yield-related attributes under optimal and deficit irrigation conditions. Biochar enhances soil structure, water retention, and nutrient availability, while improving plant nutrient uptake and drought resilience. The field experiment with maize crop was conducted in Hardaas Pur (32°38.37’N, 74°9.00’E), Gujrat, Pakistan. The experiment involved the use of DK-9108, DK-6321, and Sarhaab maize hybrid seeds, with five moisture levels of evapotranspiration (100% ETC, 80% ETC, 70% ETC, 60% ETC, and 50% ETC) maintained throughout the crop seasons. Furthermore, activated biochar was applied at three levels: 0 tons/ha (no biochar), 5 tons per hectare, and 10 tons per hectare. The study’s findings revealed significant improvements in soil organic matter, bulk density, nutrient profile and total porosity with biochar supplementation in soil. Maize plants grown under lower levels of ETC in biochar supplemented soil had enhanced membrane stability index (1.6 times higher) increased protein content (1.4 times higher), reduced malondialdehyde levels (0.7 times lower), improved antioxidant enzyme activity (1.3 times more SOD and POD activity, and 1.2 times more CAT activity), improved relative growth (1.05 times more) and enhanced yield parameters (26% more grain and stover yield, 16% more 1000-seed weight, 29% more total seed weight, 33% more apparent water productivity) than control. Additionally, among the two biochar application levels tested, the 5 tons/ha dose demonstrated superior efficiency compared to the 10 tons/ha biochar dose.

Maize (Zea mays L.), a globally significant cereal of the Poaceae family, plays a pivotal role in food and feed security. However, its productivity is increasingly threatened by climate-induced drought stress and low organic matter content of soil, particularly in arid and semi-arid regions. This study aimed to investigate the interactive effects of organically modified biochar supplementation on soil physicochemical properties, plant physiological responses, and yield performance of maize under varying irrigation regimes. The experiment was conducted under field conditions using Acacia nilotica-derived biochar and modified with vermicompost and perlite at the Botanical Garden, University of the Punjab, Lahore. The biochar was applied in the soil at two application rates (5 and 10-tons ha⁻¹), in combination with five irrigation regimes (100%, 80%, 70%, 60%, and 50% of crop evapotranspiration). Results revealed substantial improvements in soil quality and plant performance with biochar application. Specifically, the 10 tons ha⁻¹ biochar treatment significantly increased soil pH (by 6%), organic matter (by 24%), and saturation percentage (by 47.8%) compared to untreated soil. The Brunauer-Emmett-Teller (BET) surface area, and pore volume also improved with biochar application. Photosynthetic rate rose by 43.2%, while transpiration rate and total chlorophyll content increased by 9-folds and 50.5%, respectively. Yield-related parameters exhibited marked enhancement, with cob length increased by 68.3%, and thousand-seed weight by 121% under 10 tons ha⁻¹ biochar and full irrigation (100% ETc) compared to control. This study concludes that organically modified biochar serves as a promising soil amendment to improve soil fertility, enhance physiological resilience, and optimize maize yield under water-limited conditions. The findings provide a scalable strategy for sustainable crop production and resource-efficient agriculture under climate change scenarios.

Declining soil fertility due to unstable cultivation practices is a major challenge, particularly under water-limited conditions, leading to reduced crop productivity. Identifying sustainable soil amendments that enhance plant resilience and improve soil properties is crucial for ensuring food security in arid and semi-arid regions. Among these, activated acacia biochar has shown potential in improving soil quality. A pot-scale experiment was conducted to evaluate the effects of four different soil amendments i.e., biochar amended soil (BAS), vermicompost amended soil (VCAS), perlite amended soil (PAS), activated biochar amended soil (ABAS) on wheat physiology and yield under moisture stress conditions. Soil amendments were incorporated at 2.5% and 5% (dry weight basis) by through mixing. Two water regimes were applied from booting to grain filling: (i) optimal moisture (80% of field capacity, FC) (ii) moisture stress (50% of FC). The highest improvement in water holding capacity was observed in soil amended with 5% ABAS which increased by 39.31% (16.3 ± 0.72) compared to non-amended soil (NAS). Under 50% FC, plants grown in 2.5% and 5% ABAS exhibited significantly higher total chlorophyll content (11%), stomatal area (42%), stomatal aperture (29%), and guard cell area (44%) than NAS. The maximum increase in photosynthetic rate (threefold and 4.2-fold higher) and transpiration rates (threefold and 3.2-fold higher) were observed in plants of 2.5% BAS and 5% ABAS, respectively than NAS. However, the highest improvement in water use efficiency (52%) was observed in the plants of 2.5% ABAS than NAS. Leaf nutrient assessment showed a 10.4% and 7.6-fold increase in percent weight of carbon and phosphorus in the plants of BAS, 75% higher sodium in PAS, 139% higher calcium in VCAS, and 97.5% higher nitrogen and 58% higher magnesium in ABAS than NAS. Additionally, the highest accumulation of metabolites including amides, polysaccharides, lignin and waxes, was recorded in plants grown in amended soil, particularly in ABAS. Regarding yield attributes, plants grown in 2.5% and 5% ABAS had significantly (p < 0.05) higher leaf area (84–85%), spike length (89–93%), spikelet per spike (139–166%), and 1000 grain weight (133–157%) under 50% FC compared to NAS. In conclusion, activated biochar considerably enhances plant physio-biochemical attributes and yield under water stress conditions. Its applications may be recommended for farmers in arid regions to mitigate the adverse effects of water scarcity.

Water deficiency in semiarid regions is a limiting factor that affects crop quality and yield. In Punjab, Pakistan, a 27% decline in maize yield was detected over the past two decades just because of water scarcity. Currently, no studies have reported the effects of organically activated biochar (AB) on crop productivity under natural field conditions. For this purpose, a field experiment in a split-split-plot design was conducted with three amendment levels (0, 2, and 4 tonnes ac⁻¹), and three maize hybrids (DK-9108, DK-6321, and Sarhaab) under 100%, 70%, and 50% irrigation water (IW) of crop evapotranspiration (ETc). The AB significantly improved the soil’s physical and chemical properties, and maximum improvement was recorded in 4 tonnes ac⁻¹ AB amendment in organic matter (16.6%), total organic carbon (17%), phosphorus (11.43%), and available potassium (29.27%). The 4 tonnes ac⁻¹AB amendment in soil had a significant impact on total chlorophyll content (0.3–1-fold in DK-6321), carotenoid content (3.9–4.4-fold in Sarhaab), and relative water content (30% and 21% in Sarhaab) under 50% irrigation water (IW) of ETc at V14th and R3 stages, respectively. Moreover, a significant decline in stress markers (proline content and sugar content) was detected at both growth stages in all maize hybrids in AB amended soil. The analysis of plant metabolites indicated increased intensities of phenolics, alkyl esters, and carbohydrates by 2.5–7%, 17–80%, and 40–43% in DK-6321 under 50% IW in 2–4 tonnes ac⁻¹ AB amended soil, respectively. The highest improvement in growth and yield attributes among maize hybrids was detected in the order DK-6321¿DK-9108¿Sarhaab in 2–4 tonnes ac⁻¹AB amended soil under 70% and 50% IW of ETc, respectively. Hence, this research might help to develop an effective soil amendment to restore degraded soils and improve maize growth under arid climatic conditions.