The use of chemical fertilizers, particularly phosphorus fertilizers, significantly boosts agricultural productivity but also incurs environmental and economic costs. Recent advancements have explored the use of biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More as a soil amendmentA soil amendment is any material added to the soil to enhance its physical or chemical properties, improving its suitability for plant growth. Biochar is considered a soil amendment as it can improve soil structure, water retention, nutrient availability, and microbial activity.   More and a base for slow-release fertilizers. A recent study at Zanjan University’s Faculty of Agriculture investigated the phosphorus release behavior from monopotassium phosphate fertilizers derived from various biochar sources, including walnut shell residues, grape pruning, and wheat stubble.

The experiment, designed as a factorial study with randomized complete blocks and three replications, examined the effects of two pyrolysis temperatures (350°C and 650°C) and biochar types (walnut shell, grape pruning, and wheat stubble) combined with phosphorus fertilizer (10% and 20% by weight).

Results indicated that both pyrolysis temperature and biochar type significantly influenced the physical and chemical properties of the biochar-based fertilizer tablets, such as density, pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More, and electrical conductivity. Phosphorus release was gradual in water across all biochar types, with a higher release rate at the experiment’s onset. Wheat stubble biochar exhibited the lowest phosphorus release rates compared to walnut shell and grape pruning biochars, with release percentages being 4.6% and 8.54% lower at the end of the experiment for 350°C and 650°C pyrolysis temperatures, respectively.

In soil, wheat stubble biochar also demonstrated the lowest phosphorus release, while grape pruning residues showed the highest. Furthermore, biochar type significantly impacted the corn plant shoot performance, with wheat stubble biochar-based controlled-release fertilizers yielding the highest plant performance.

Overall, granulating chemical fertilizers with biochar proves to be an effective strategy for creating slow-release fertilizers, potentially mitigating the environmental and economic challenges associated with conventional chemical fertilizers.