Dayoub, et al (2024) Chemical and Physical Properties of Selected 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 Types and a Few Application Methods in Agriculture. Agronomy. https://doi.org/10.3390/agronomy14112540

Biochar, a carbon-rich by-product of organic matter pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More, is gaining attention for its potential agricultural benefits. Produced through the high-temperature decomposition of organic materials like plant residues and sewage sludge, biochar’s properties are influenced by factors such as feedstockFeedstock refers to the raw organic material used to produce biochar. This can include a wide range of materials, such as wood chips, agricultural residues, and animal manure. More type and pyrolysis temperature. A recent review explores biochar’s chemical and physical properties across various types and application methods, highlighting its role in soil and crop improvement.

Key Biochar Properties

The properties of biochar vary significantly with pyrolysis temperature, which impacts its chemical composition and physical characteristics. As pyrolysis temperatures increase, biochar typically exhibits a higher 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, electrical conductivity (EC), and ashAsh is the non-combustible inorganic residue that remains after organic matter, like wood or biomass, is completely burned. It consists mainly of minerals and is different from biochar, which is produced through incomplete combustion.   Ash Ash is the residue that remains after the complete More content. These chemical changes make it more suitable for certain soil types, particularly acidic soils, where a higher pH can improve conditions for plant growth. However, the yield and nitrogen content of biochar tend to decrease as temperatures rise, which could affect its nutrient supply potential in certain applications.

Physical properties like porosityPorosity of biochar is a key factor in its effectiveness as a soil amendment and its ability to retain water and nutrients. Biochar’s porosity is influenced by feedstock type and pyrolysis temperature, and it plays a crucial role in microbial activity and overall soil health. Biochar More and specific surface area (SSA) also increase with temperature, enhancing biochar’s ability to retain water and nutrients within soil. Among different biochar sources, woody biochar generally shows greater increases in SSA and porosity compared to other feedstocks, making it particularly useful in water-limited conditions where soil moisture retention is critical.

Application Methods

Biochar can be applied directly to soil, with techniques varying based on crop needs and soil conditions. Traditional methods include mixing biochar into the topsoil or incorporating it into planting holes. Mixing biochar at deeper soil levels (up to 20 cm) has shown positive effects on soil quality, especially in long-term applications. The review also highlights “reapplication” benefits, where repeated doses of biochar, especially when combined with nutrients, have improved soil moisture, structure, and nutrient retention over time.

A novel approach gaining popularity is the foliar application of biochar extracts, which are sprayed onto plants in a similar way to liquid fertilizers. This method allows plants to absorb essential minerals like magnesium and iron directly through their leaves, promoting photosynthesis and enhancing growth. Studies show that foliar biochar application boosts chlorophyll content and increases yield in crops like wheat and pepper, especially when applied at higher concentrations.

Enhancing Biochar Properties

To maximize biochar’s agricultural benefits, researchers are exploring modifications that enhance its properties. Methods such as chemical treatments, steaming, and even ball milling improve biochar’s surface area, porosity, and functional groups. For example, treating biochar with acids can introduce oxygen-containing functional groups, increasing its cation exchange capacity (CEC), a trait that supports nutrient exchange within the soil. Similarly, steamed or aged biochar has shown improved porosity and mineral retention, which can further enhance its effects when applied to soil.

As biochar research advances, its role in sustainable agriculture is expanding. Its ability to improve soil structure, increase water and nutrient retention, and enhance plant growth positions biochar as a valuable tool for managing agricultural challenges. Future research will likely focus on optimizing application methods for specific crops and climates, aiming to establish biochar as an integral component of eco-friendly farming practices.

This review underscores biochar’s versatility and effectiveness in supporting sustainable agriculture. By fine-tuning biochar’s production and application, farmers and researchers can harness its full potential to improve soil health, increase crop yields, and reduce environmental impact.