فصلنامه
نوع مقاله : مقالات پژوهشی
نویسندگان
گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه زنجان، زنجان، ایران
کلیدواژهها
عنوان مقاله English
نویسندگان English
Phosphorus (P) deficiency is a major limitation in agricultural soils worldwide, particularly in calcareous soils where phosphorus availability is inherently low due to fixation by calcium compounds. Phosphorus is an essential macronutrient for plants, playing critical roles in energy transfer, photosynthesis, and metabolic processes. Insufficient phosphorus not only reduces crop yield but also affects plant quality and overall ecosystem sustainability. Traditional phosphorus fertilizers, such as triple superphosphate (TSP) and monoammonium phosphate (MAP), are often applied in high doses to compensate for low availability, which can lead to environmental concerns, including phosphorus runoff and eutrophication of water bodies. In recent years, biochar-based fertilizers have emerged as a promising approach to improve soil fertility, enhance nutrient retention, and increase crop nutrient use efficiency. Biochars derived from different feedstocks and produced at varying pyrolysis temperatures possess distinct physicochemical properties that influence nutrient adsorption, soil microbial activity, and plant growth. Moreover, enriching biochar with iron oxide can further improve phosphorus availability by reducing phosphorus fixation and providing a slow-release nutrient source. Despite these advances, the combined effect of phosphorus-enriched biochar and iron oxide on crop growth, nutrient use efficiency, and chlorophyll content remains insufficiently studied. Therefore, this study aimed to evaluate the effects of phosphorus-based biochar-iron oxide composites on the growth performance and phosphorus use efficiency in corn (Zea mays L.) under controlled greenhouse conditions.
Materials and Methods
A greenhouse experiment was conducted using a factorial design based on a completely randomized layout with three replications. Treatments included a control (without biochar and iron oxide), two types of biochar produced from wheat straw and walnut shell at two pyrolysis temperatures (350°C and 650°C), a single iron source (Fe(NO3)3), and two phosphorus levels (0 and 20% by weight) applied as TSP or MAP. Corn plants were cultivated under controlled environmental conditions, and soil moisture, temperature, and light were monitored throughout the 21-day incubation period. Plant growth parameters were measured, including fresh and dry biomass of aerial parts, plant height, and leaf area. Chlorophyll content was determined using a SPAD meter. Phosphorus use efficiency was estimated by comparing biomass production relative to the phosphorus applied. Statistical analyses were performed to evaluate the effects of biochar type, pyrolysis temperature, phosphorus source, and iron oxide enrichment on growth parameters. The interactions between these factors were also examined to understand the synergistic effects on corn performance.
Results and Discussion
The results indicated that phosphorus addition significantly enhanced corn growth and chlorophyll content compared to the control treatment without phosphorus. Among biochar treatments, wheat straw biochar produced at 350°C in combination with 20 mg phosphorus (MAP or TSP) resulted in the highest vegetative growth and biomass of aerial parts, while walnut shell biochar at 650°C and the control treatment exhibited the lowest performance. The inclusion of iron oxide in biochar further improved biomass accumulation. For example, wheat straw and walnut shell biochars produced at 350°C increased fresh and dry biomass of aerial parts by 18.6% (2.18%) and 7.9% (9.17%), respectively, relative to the non-biochar control. At 650°C, only wheat straw biochar showed a significant increase in aerial biomass.
These findings suggest that both biochar feedstock and pyrolysis temperature are critical factors influencing the effectiveness of phosphorus-enriched biochar as a slow-release fertilizer. The results also indicated that the type of phosphorus fertilizer (MAP vs. TSP) had no significant effect on growth performance, emphasizing the importance of biochar-mediated phosphorus delivery rather than the source itself. Moreover, the positive impact on chlorophyll content implies that biochar-based phosphorus composites can improve photosynthetic efficiency and overall plant health. These outcomes highlight the potential of using phosphorus-iron oxide biochar composites as a sustainable strategy for enhancing nutrient use efficiency in crops while minimizing environmental impacts.
Conclusion
In summary, this study demonstrates that phosphorus-based biochar-iron oxide composites can serve as effective slow-release fertilizers, improving phosphorus availability, crop growth, and nutrient use efficiency. Wheat straw biochar produced at lower pyrolysis temperatures (350°C) was particularly effective in promoting vegetative growth, whereas the feedstock type and pyrolysis temperature were more influential than the phosphorus source itself. The application of these composites could contribute to sustainable agricultural practices by reducing reliance on conventional phosphorus fertilizers, mitigating environmental risks, and supporting crop productivity in phosphorus-deficient soils. Future studies are recommended to evaluate long-term field applications and interactions with soil microbial communities to further optimize biochar-based phosphorus management strategies.
کلیدواژهها English
