The results showed that biochar significantly improved soil quality, enhancing key indicators such as total C, N, P, K, Ca, cation exchange capacity, and moisture retention.. Recent stud
INTRODUCTION
Research rationale
Soil degradation is a critical challenge in Vietnam, primarily caused by the overuse of chemical fertilizers and pesticides in agriculture Gray soils, classified as Haplic Acrisols, are especially affected, experiencing severe nutrient depletion, acidification, and structural damage due to unsustainable farming practices This ongoing degradation leads to poor soil health, reduced crop productivity, and notable environmental impacts Addressing these issues is essential for sustainable agricultural development in the region (Truc et al., 2016).
Improper soil health management in Vietnamese agriculture has led to significant soil erosion, loss of organic matter, and pollution from agrochemical leaching into ecosystems Haplic Acrisols, common in these regions, are naturally low in fertility, poorly retain water, and are highly acidic, making them highly vulnerable to erosion and nutrient leaching These conditions collectively reduce agricultural productivity, disrupt ecosystem balance, and threaten the livelihoods of rural farmers In areas such as Thai Nguyen province, where gray soil dominates, these challenges are especially acute, emphasizing the urgent need for sustainable soil management practices.
Addressing soil degradation is essential for enhancing crop yields, reducing agriculture's environmental impact, and securing long-term food security Conventional methods like excessive chemical inputs have failed to offer sustainable solutions, underscoring the need for environmentally friendly alternatives Implementing innovative, eco-friendly practices is crucial to restore soil fertility and promote sustainable agriculture in degraded regions.
Biochar, a carbon-rich material produced through the pyrolysis of organic biomass like agricultural by-products in an oxygen-limited environment, offers promising solutions for sustainable agriculture Recent research shows that biochar improves soil structure, enhances nutrient retention, reduces soil acidity, increases water-holding capacity, and helps mitigate greenhouse gas emissions These significant agronomic and environmental benefits make biochar an effective tool for rehabilitating Haplic Acrisols and boosting agricultural productivity.
Biochar enhances soil physical and chemical properties, promoting healthy plant growth by improving porosity, reducing bulk density, and increasing cation exchange capacity (CEC) This process boosts nutrient availability and retention, making essential nutrients more accessible to crops Additionally, biochar buffers soil pH, helping to mitigate acidity issues in gray soils and support optimal growing conditions (Phuong et al., 2019).
Biochar production provides a sustainable waste management solution by transforming agricultural residues like rice husk, coconut shell, and sawdust into valuable soil amendments This process helps reduce pollution and greenhouse gas emissions caused by open burning of crop residues By converting these by-products into biochar, Vietnam can enhance soil health, decrease environmental pollution, and sequester carbon Additionally, this promotes the circular use of agricultural resources, supporting sustainable farming practices.
Gray soil degradation in Vietnam threatens agricultural productivity, food security, and environmental sustainability The ongoing use of chemical inputs worsens soil quality, highlighting the need for sustainable solutions to restore soil health Biochar emerges as a promising alternative, enhancing soil structure, increasing nutrient retention, and improving water-holding capacity Additionally, biochar offers an eco-friendly method for managing agricultural waste, supporting environmentally sustainable farming practices.
Further research is essential to fully understand the potential of biochar in Vietnamese agriculture, especially for improving Haplic Acrisols Addressing these knowledge gaps and promoting biochar adoption through supportive policies and education can enhance the sustainability of Vietnam’s agricultural sector Ultimately, leveraging biochar contributes to global climate change mitigation by improving soil health and increasing carbon sequestration efforts.
Research’s objectives
- Evaluate changes in the physicochemical properties of soils treated with biochar, including parameters such as pH, cation exchange capacity (CEC), and organic matter content
- Examine the effects of biochar on soil water retention and its relationship with biochar pore structure and application ratios
- Compare the cost-effectiveness of biochar applications with synthetic fertilizers, focusing on input costs, crop yield improvements, and long-term soil health benefits.
Research questions
- What are the specific impacts of biochar produced from agricultural by- products on the physical, chemical, and biological properties of Haplic Acrisols?
- How does the application of biochar affect soil fertility and water retention in degraded soils?
- Can biochar significantly ways for solutions to improve degraded grey soil quality?
Research hypotheses
- Biochar from agricultural by-products improves the physical properties of Haplic Acrisols, increasing water retention and reducing soil compaction
- It enhances soil chemical properties, such as pH, nutrient availability, and cation exchange capacity (CEC)
- Biochar boosts soil biological activity, increasing microbial biomass and enzyme activity
- Biochar improves soil properties such as pH, moisture retention, and nutrient availability
- The source of biochar influences its effectiveness
- Higher biochar proportions yield better soil improvements but plateau beyond a threshold.
Limitations
Most existing research on biochar primarily examines its short-term impacts, leaving a gap in understanding of its long-term effects on soil health, crop productivity, and carbon sequestration in Vietnam To fully evaluate biochar’s sustainability and durability, longitudinal studies are essential, providing deeper insights into its ongoing benefits and potential risks for agricultural ecosystems.
Economic feasibility remains a key challenge for the widespread adoption of biochar among smallholder farmers To promote its use, research must focus on evaluating the cost-effectiveness of biochar production and application, ensuring that benefits outweigh expenses Additionally, exploring supportive policies and incentives can play a vital role in encouraging smallholders to integrate biochar into their farming practices, ultimately enhancing sustainable agriculture.
A major obstacle to the widespread adoption of biochar is the limited awareness among farmers and policymakers To promote its use, further research is essential to inform effective policy development, including targeted subsidies, extension services, and educational programs Increasing awareness and knowledge can significantly enhance the adoption of biochar as a sustainable soil amendment.
- Site-Specific Results: Biochar’s effectiveness may vary by local soil conditions, climate, and crop type, limiting generalizability to other regions
- Long-Term Impacts: While short-term soil improvements are evaluated, the long-term effects of biochar require prolonged study
- Financial and Resource Constraints: Limited funding and resources may restrict the scale of field trials and analyses
- Uncertainty in Biochar Quality: Variability in biochar properties based on feedstock and production methods could introduce inconsistencies in results.
LITERATURE REVIEW
Some Basic Concepts
According to Vietnam's Environmental Protection Law 2020, the environment is an interconnected system of natural and man-made elements surrounding and influencing human life, economic activities, and ecosystems It encompasses air, water, soil, biodiversity, and ecosystems, highlighting the importance of sustainable management to maintain ecological balance Environmental pollution, particularly soil pollution, results from harmful alterations caused by hazardous waste, chemical fertilizers, and industrial activities Soil contamination reduces soil fertility and poses serious health risks to humans and ecosystems, emphasizing the need for effective environmental protection measures.
Scrap materials are substances recovered from discarded items during production, business, or consumption, which can be repurposed as raw inputs for new manufacturing cycles Recycling and waste management of these materials are essential for reducing raw material consumption and minimizing environmental impact Reprocessing scrap materials helps industries lower waste, conserve energy, and reduce their environmental footprint, promoting a circular economy where resources are continuously reused According to a 2023 study by Smith and Johnson, effective recycling processes can significantly cut the carbon footprint linked to manufacturing new products.
Environmental technical standards are mandatory regulations that set limits on specific environmental quality parameters and pollutant concentrations in raw materials, fuels, products, equipment, and waste Enforced by government agencies, these standards aim to prevent industries and agricultural processes from exceeding pollution levels, thereby safeguarding ecosystems, human health, and the environment They serve as essential guidelines for industries to adopt cleaner technologies and ensure a baseline of environmental protection, all based on scientific research and legal frameworks.
Environmental standards are voluntary guidelines that organizations and industries can adopt to improve their environmental performance These standards specify acceptable limits for pollutant levels in emissions and waste, providing a framework for sustainable practices Although not legally binding, complying with environmental standards helps businesses demonstrate their commitment to sustainability, reduce environmental impact, and gain competitive advantages, such as access to eco-conscious markets and meeting international trade requirements.
A review by the International Organization for Standardization (ISO) highlights how adherence to environmental standards can lead to significant cost savings and improved operational efficiency (ISO, 2015)
According to UNESCO, the environment encompasses both natural ecosystems and human-made systems that surround individuals, highlighting its dual nature Human activity plays a crucial role in shaping the environment, as people exploit natural and artificial resources to meet their needs This interaction includes the transformation of landscapes for agriculture, industry, and urban development, emphasizing the significant impact of human actions on the environment—both positive and negative.
Environmental pollution, defined by the WHO as the introduction of hazardous waste or energy into the environment that adversely affects living organisms and environmental quality, poses significant health and ecological risks It manifests in various forms, including air, water, soil, and noise pollution, primarily resulting from human activities like industrial processes, agriculture, and waste disposal The impacts of pollution extend beyond individual species to entire ecosystems, causing biodiversity loss, health problems, and long-term environmental degradation Recent research highlights the alarming presence of microplastics and pharmaceuticals in food chains, threatening both ecological systems and human health (Díaz et al., 2019).
Biochar, also known as BC, is a carbon-rich soil amendment produced through the pyrolysis of wood or plant-based materials in a low-oxygen environment This thermal decomposition process retains much of the original structure while significantly increasing the surface area, making biochar highly beneficial for soil health It enhances soil fertility by storing and gradually releasing essential nutrients, thanks to its high cation exchange capacity, which is especially valuable in degraded soils affected by drought or high temperatures Moreover, biochar serves as an effective tool for carbon sequestration, with the stored carbon remaining stable in soils for hundreds or even thousands of years, thus contributing to climate change mitigation (Shaaban et al., 2018; Liu et al., 2017; Quý and Uyên; Thắng).
Haplic Acrisols, also known as Haplic Acrisols in the FAO-UNESCO classification, are prevalent soils in Southeast Asia, the Central Highlands, and the Northern Midlands of Vietnam These soils generally develop on ancient alluvial deposits, acidic magma rocks, and sandstone, contributing to their unique characteristics Known for their low fertility, poor structure, and high susceptibility to erosion, Haplic Acrisols pose challenges for sustainable agriculture and land management in affected regions Understanding their distribution and properties is essential for effective soil conservation and crop cultivation strategies.
Gray-degraded soils in Vietnam pose a major challenge for agriculture, requiring extensive soil amendments to boost productivity (Tran, 2015) Rehabilitation efforts focus on increasing organic matter, enhancing nutrient availability, and stabilizing soil structure through biochar application, crop rotation, and organic farming practices Research indicates that biochar significantly improves soil quality by enhancing nutrient retention and microbial activity, which are vital for restoring the ecological balance of degraded lands (Nguyen et al., 2018).
Agricultural by-products, such as rice husks, corn stalks, and wood, are organic materials that do not meet quality or size standards and are typically discarded Despite being deemed waste, these by-products are a valuable source of energy and nutrients resulting from natural biological processes like photosynthesis They can be repurposed for sustainable uses such as biochar production, composting, or animal feed, thereby reducing agricultural waste and enhancing resource efficiency Utilizing agricultural by-products for biochar not only minimizes greenhouse gas emissions but also improves soil health, providing a mutually beneficial solution for farmers and the environment (Woolf et al., 2010).
Legal Framework
Relevant documents in the research area with current effectiveness:
- Environmental Protection Law 2020: Enacted by the National Assembly of the Socialist Republic of Vietnam on November 17, 2020, effective from January 1, 2024
- TCVN 8662:2001: Soil Quality - Determination of Easy Soluble Potassium
- TCVN 8940:2011: Soil Quality - Determination of Total Phosphorus - Colorimetric Method
- National Standard TCVN 5979:2007 (ISO 10390:2005): Soil Quality - Determination of pH
- TCVN 6498:1999: Determination of Nitrogen Content (Ammonium- Nitrate, Nitrite-Nitrogen, Nitrogen in Organic Compounds) in Soil
-National Standard TCVN 6650:2000: Electrical Conductivity Determination, Issued on October 24, 2008
- TCVN 9015-2:2011: Plants - Determination of Total Calcium and Magnesium - Part 2: Atomic Absorption Spectrometry Method
- National Standard TCVN 8567:2010: Soil Quality - Determination of Particle Size Composition in Soil
- TCVN 7538-2:2005 (ISO 10381-2:2002): Soil Quality - Sampling
- TCVN 4048:2011: Soil Quality - Determination of Moisture and Dry Bulk Density
Practical Background
2.3.1.Usage of Biochar from Agricultural By-products in Vietnam
With the characteristics of an agricultural country, Vietnam generates a significant amount of by-products every year from various sources, creating opportunities for employment and enhancing environmental protection
In 2022, Thai Nguyen province's forest land covered over 4,163 hectares, producing more than 255,000 m³ of timber from planted forests The 2023 afforestation plan aims to add 3,435 hectares, including 1,535 hectares of government-supported concentrated planting, with 245 hectares designated for protective forests and 3,190 hectares for production forests, maintaining a forest cover rate above 46% Timber exploitation and processing generate significant wood scraps and sawdust, which can be effectively repurposed into biochar—an environmentally friendly solution that conserves raw materials and reduces waste.
The Vietnamese wood industry plays a vital role in the national economy, producing a wide range of products such as furniture, decorative wooden items, and construction wood for export In 2020, Vietnam's production of sawdust and processed wood reached approximately 33.2 million cubic meters, marking an 8.3% increase from the previous year Additionally, Vietnam is among the world's leading wood exporters, with the export value of wood and wood products amounting to around 13.17 billion USD in 2020.
Despite Vietnam’s policies and regulations for sustainable forest management, illegal logging continues to threaten natural ecosystems, highlighting the urgent need to promote recycled wood and alternative sources to reduce pressure on forests The government has taken measures such as establishing nature reserves, banning logging in national parks, and increasing monitoring of timber trade to ensure the sustainable use of forest resources Promoting recycled and alternative wood sources is crucial for conserving Vietnam’s forests and maintaining ecological balance.
Recent research on the lifecycle of biochar from wood residues highlights its long-term benefits for sustainable agriculture Integrating biochar into farming practices enhances soil fertility, improves moisture retention, and increases nutrient availability This dual advantage not only helps reduce agricultural waste but also supports environmentally friendly farming methods (Tran and Do, 2023).
Agricultural by-products like rice husks and coconut shells are often discarded or burned, leading to environmental pollution and health risks In rural areas, these residues are frequently wasted or sold at low prices due to limited utilization options Converting these agricultural residues into biochar offers a sustainable solution for waste management, adding value while protecting the environment.
Research indicates that rice husk biochar significantly enhances soil fertility and agricultural productivity as a sustainable alternative to chemical fertilizers The study by Tran et al (2021) found that rice husk biochar improves soil physical properties, including porosity and water retention, which are essential for increasing crop resilience to climate variability Incorporating rice husk biochar into soil management practices can boost crop yields while promoting environmental sustainability.
Coconut shell biochar has significant potential as an organic soil amendment to reduce reliance on synthetic fertilizers Research indicates that biochar enhances nutrient retention in the soil, ensuring nutrients remain available to plants for extended periods This improvement in soil fertility not only boosts plant growth but also helps minimize runoff of harmful substances into nearby water bodies, promoting environmental sustainability (Le et al., 2022).
Vietnam possesses significant potential for biochar production thanks to its plentiful agricultural and livestock by-products Despite this, biochar utilization is still in its early stages and remains underdeveloped across the country Although some businesses have started manufacturing and supplying biochar to the market, production capacity and scale are currently limited, highlighting the need for further development and investment in this sustainable solution.
Biochar is mainly used in agriculture as an organic fertilizer and soil amendment, promoting sustainable farming practices However, challenges remain, including high production costs, management complexities, and transportation issues that hinder widespread adoption Furthermore, the absence of clear policies and regulations limits the development and effective utilization of biochar in the agricultural sector.
A study highlighted the need for government support and research initiatives to promote biochar use in agriculture, particularly to mitigate greenhouse gas emissions and environmental pollution (Hoang et al 2023)
Le et al (2024) demonstrated that, despite high initial investment costs, biochar production can be economically viable and profitable over the long term due to its environmental benefits and contribution to Vietnam’s climate goals They emphasized the importance of government-backed incentive programs to reduce entry barriers, especially for small and medium-sized enterprises (SMEs), to promote sustainable biochar development.
A multi-stakeholder approach is essential for promoting biochar technology adoption in Vietnam Combining public policy support, private sector investment, and grassroots education can significantly accelerate biochar utilization This integrated strategy helps embed biochar into Vietnam’s circular economy, effectively reducing waste and enhancing resource efficiency.
2.3.2 Global Utilization of Biochar from Agricultural By-products
Biochar, produced through the pyrolysis of organic waste in oxygen-limited environments, plays a vital role in both agriculture and environmental protection by improving soil fertility and aiding carbon sequestration It reduces methane emissions from organic waste decomposition, neutralizes pollutants, and supplies essential nutrients to plants, promoting healthier crop growth Its porous structure enhances soil water retention and cation exchange capacity, leading to improved soil health and increased crop yields The rising global awareness of climate change and sustainable farming practices has fueled interest in biochar as a tool to combat soil degradation and reduce carbon emissions, highlighting its significance in sustainable development.
Global biochar production has grown rapidly due to its recognized environmental benefits and potential to enhance agricultural productivity By 2018, total production reached 130 million tons, with Europe and North America dominating the industry, collectively accounting for 84% of the global output.
The European Union has established itself as a major producer of biochar, supported by policy frameworks that promote renewable energy and sustainable farming practices In North America, biochar production has significantly increased, driven by environmental policies such as those advocated by the Environmental Protection Agency (EPA), which emphasizes biochar’s role in reducing greenhouse gas emissions and enhancing soil health (Verheijen et al., 2019).
Biochar consumption is rapidly increasing in Asia, especially in China and India, driven by large-scale agricultural needs and sustainable soil management initiatives China, as the world’s largest agricultural producer, is utilizing biochar to improve soil health, enhance crop yields, and reduce reliance on chemical fertilizers (Liu et al., 2019) Meanwhile, India adopts biochar to tackle soil salinity and water scarcity in drought-prone regions Despite these growing uses, Asia's share of the global biochar market remains relatively small, indicating significant potential for industry expansion.
Overview of Biochar Production and Applications
Vietnam’s abundant agricultural residues, such as rice husks, corn stalks, and sawdust, offer valuable feedstocks for sustainable biochar production Utilizing these by-products helps reduce agricultural waste and promotes eco-friendly soil management practices This cost-effective approach supports environmental sustainability while adding value to agricultural waste streams.
Economic studies show that biochar production costs range from $50 to $150 per ton, influenced by feedstock type and pyrolysis methods Despite these costs, the potential benefits—such as 15–30% crop yield increases—make biochar a promising investment Successful projects in Southeast Asia have demonstrated pollution reduction, economic benefits, and enhanced soil fertility, providing valuable insights for Vietnam’s sustainable agriculture development.
Biochar has gained significant recognition as an eco-friendly, sustainable solution for climate change mitigation and soil enhancement Produced through pyrolysis of organic biomass at low temperatures below 700°C under limited oxygen conditions, biochar results in porous, carbon-rich particles Its high stability in soil and unique structure helps improve soil fertility, water retention, and nutrient availability, making it an effective tool for sustainable agriculture.
Environmental Science, 2023) Moreover, the production of biochar sequesters carbon from the atmosphere, making it an effective tool for reducing greenhouse gas emissions (MDPI, 2023)
Biochar application in agriculture is gaining significant attention for its potential to improve soil fertility Research indicates that biochar positively affects essential soil properties such as pH balance, organic carbon levels, and moisture retention, thereby enhancing overall soil health For example, studies by Quy et al demonstrate that incorporating biochar into soils can lead to measurable improvements in these key soil attributes, supporting sustainable agriculture practices.
Research in 2019 investigated biochar produced from rice straw at pyrolysis temperatures of 300°C, 450°C, and 600°C, revealing that biochar application significantly enhances the physicochemical properties of Haplic Acrisols, thereby improving soil fertility and health The study also found that adding biochar reduces the soil’s capacity to adsorb ammonium (N-NH4+), highlighting the importance of careful ammonium fertilizer management to prevent over-fertilization and environmental pollution.
Recent research indicates that the effectiveness of biochar in enhancing soil structure and nutrient retention is highly dependent on both pyrolysis temperature and biomass type Studies, such as Uyen et al (2019), have shown that biochar's ammonium adsorption capacity varies with production temperature, with lower temperature biochar (300°C) resulting in a less significant reduction in ammonium adsorption compared to biochar produced at higher temperatures (450°C and 600°C) These findings highlight the importance of optimizing biochar production parameters to maximize its benefits for specific agricultural applications.
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2010) Furthermore, the pyrolysis conditions, particularly temperature, greatly influence the biochar's surface area, porosity, and its ability to retain water and nutrients in soil
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The relationship between biochar, soil, plant, and environment illustrated in figure 2.1 below
Figure 2.1 Applications of biochar in soil, plant, and environment
- Enhanced Soil and Crop Productivity
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Biochar application effectively increases soil pH, especially in acidic soils, by neutralizing harmful acids and reducing the mobility of toxic elements such as aluminum This improvement creates a healthier chemical environment for plant roots and enhances the availability of essential nutrients like calcium, magnesium, and potassium Additionally, biochar boosts the availability of vital nutrients such as nitrogen and phosphorus, promoting better plant growth and overall soil fertility (Major et al., 2010).
Biochar enhances soil nutrient retention by its high cation exchange capacity (CEC), helping to retain essential nutrients like nitrogen, potassium, and phosphorus in the root zone This reduces nutrient leaching and ensures crops have access to vital nutrients for a longer period, which is especially beneficial in sandy or degraded soils prone to nutrient washout from rainwater or irrigation (Son et al., 2011).
- Increased Water Retention and Soil Structure Stability
Biochar’s porous structure enhances water retention, making it an ideal soil amendment for drought-prone areas and soils with poor water-holding capacity This increased water retention supports plant growth during dry periods and helps reduce soil erosion by stabilizing soil aggregates Additionally, biochar improves soil structure, preventing surface runoff, promoting water infiltration, and further reducing erosion, thus contributing to healthier and more resilient soils.
- Soil Remediation for Environmental Pollution
Biochar is a promising solution for soil remediation due to its capacity to adsorb a wide range of pollutants, including nitrogen compounds, PAHs, pesticides, and heavy metals It effectively reduces soil contamination and enhances soil quality in polluted environments For example, Chai et al (2012) demonstrated that biochar can decrease the bioavailability of heavy metals like cadmium and lead, confirming its potential as an efficient soil remediation agent.
Biochar can influence pesticide effectiveness by adsorbing residues and reducing soil pesticide concentrations, thereby lowering environmental impact Its effect on herbicide efficacy varies depending on the chemical properties of both biochar and the herbicide While biochar has been shown to reduce pesticide leaching, it may also diminish herbicide performance, necessitating adjustments in application rates to ensure effective pest control (Pignatello et al., 2018).
- Biochar as a Renewable Energy Source
Overview of Haplic Acrisols
Approximately 3 million hectares of Vietnam's gray soil are degraded Perennial rice fields are the main locations for this type of soil in agricultural output It is 800 hectares in size, or 0.16% of the whole natural area, and is made up of only one type of soil: Haplic Acrisols atop sandy and acidic lava rock Haplic Acrisols has a light to medium-textured mechanical composition with a combination of durable primary minerals It is formed by the weathering of granite and various types of sandy rocks that are rich in silica and low in critical minerals Because of its distribution on sloping terrain, intense erosion processes occur, resulting in the leaching of organic matter and iron, turning the soil's surface layer silver-white This soil type is naturally low in fertility, and without correct nutrient management measures, it can readily degrade into infertile rocky soil, reducing productivity
Degraded gray soils in Vietnam are characterized by low organic matter content (below 1%), high acidity with pH levels between 4.0 and 5.0, and poor water retention capabilities These soil properties significantly hinder their productivity, leading to lower crop yields and increased dependence on synthetic fertilizers and agrochemicals.
Tropical regions worldwide face similar challenges of soil degradation caused by intensive agriculture and deforestation Vietnam's experience mirrors these global trends, emphasizing the urgent need for sustainable solutions such as biochar Implementing biochar can effectively restore soil health, improve fertility, and help maintain agricultural productivity in degraded lands.
- Haplic Acrisols has a mechanical composition ranging from light to medium, bulk density between 1.30-1.50 g/cm³, density between 2.65-2.70
The soil moisture content between 50-70 cm and 250 cm depths consistently remains around 80-100% of the maximum water-holding capacity, ensuring adequate water availability for plant growth However, during the dry season, soil moisture drops significantly to merely 21-24%, primarily caused by soil compaction that reduces water retention Soil porosity varies within this profile, influencing water movement and retention, and plays a crucial role in maintaining soil health and crop productivity Understanding these moisture dynamics and porosity levels is essential for effective soil management and optimizing agricultural yield.
43 to 45%, paddy fields have a moisture retention capacity of 27-31%, and wilting point moisture is 5-7%
- The pH of the soil ranges from somewhat acidic to very acidic, with average pH of KCl values of 3.0-4.5
- The organic matter level of the surface soil layer ranges from poor to extremely poor (0.50-1.50%), and both total and accessible nutrients are insufficient
- The soil has low cation exchange capacity (Ca++Mg++ < 2 meq/100 g), nitrogen availability, and water retention capacity
*Relationship between physical and chemical soil properties
Understanding the physical properties of soil, such as aggregate stability, water holding capacity, bulk density, and overall soil stability, is essential because they directly influence chemical properties Improved soil conditions, like reduced compaction and increased water retention, enhance porosity, which positively impacts pH levels, cation exchange capacity (CEC), nutrient retention, and nutrient uptake These improvements lead to higher crop yields and more efficient mineralization and nutrient cycling, promoting healthier and more productive soils.
*Relationship between chemical and biological soil properties
Soil chemical properties such as pH, cation exchange capacity (CEC), and carbon-nitrogen cycling are crucial factors that influence biological activity in the soil Maintaining an optimal pH and nutrient levels enhances microbial respiration, enzyme activity, and microbial biomass carbon and nitrogen (MBC), supporting healthy microbial populations A balanced chemical environment promotes microbial growth, which is essential for efficient nutrient cycling and organic matter decomposition, ultimately improving overall soil quality and fertility.
*Relationship between physical and biological soil properties
Healthy soil physical properties, including optimal soil structure, water retention, and aeration, are crucial for supporting vibrant microbial communities Well-structured soil promotes microbial activity, enzyme functions, and respiration, which enhance the breakdown of organic matter This process is vital for efficient carbon and nitrogen cycling, ultimately maintaining soil health and fertility.
*Relationship between environmental quality and soil properties
Improving environmental quality involves enhancing soil's physical, chemical, and biological properties to boost carbon sequestration and reduce greenhouse gas emissions Better soil structure and water retention capabilities directly contribute to increased carbon storage, helping mitigate climate change Additionally, promoting microbial activity and nutrient cycling enhances the breakdown of pollutants and improves the remediation potential of degraded soil and water systems, supporting overall environmental health.
METHODS
Research Object and Scope
- Biochar derived from agricultural waste (rice husk, wood shavings, sawdust, and wood scraps)
- In terms of scope and space: Experiments will be conducted on a laboratory scale at the faculty of Environment, Thai Nguyen University of Agriculture and Forestry.
Location and Timeframe
- Location: The research will be carried out in the laboratory from faculty of Environment, Thai Nguyen University of Agriculture and Forestry
Research Content
- Investigate and evaluate the physical and chemical properties of Haplic Acrisols
- Study the soil improvement potential of Haplic Acrisols by using various types of biochar derived from agricultural by-products
- Research the application process of biochar to regenerate Haplic Acrisols
- Propose solutions to enhance the quality of Haplic Acrisols in agricultural by-products.
Research Methodology
3.4.1 Investigation and Data Collection Methods
- Utilize various forms of literature, including internationally published papers, books, and specialized journals for synthesis and analysis
- Employ internet resources for data retrieval and synthesis
- Request consultations from experts, researchers, etc
- Collect data and research materials on Biochar within and outside the country as a basis for comparison and analysis of its properties with the Biochar created in the study
Raw materials such as rice husks, wood shavings, sawdust, and wood scraps were collected from the Dong Hy district in Thai Nguyen province, an area characterized by degraded gray soils To ensure consistency, samples were extracted from a 10 cm depth using a stainless-steel auger, and GPS coordinates were recorded at each sampling site for precise replication of the study.
After collection, raw materials were thoroughly washed with tap water followed by deionized (DI) water to eliminate water-soluble impurities and dirt Once cleaned, they were dried at 80°C for 48 hours to ensure complete moisture removal The dried materials were then stored in zip bags for preservation.
The raw material was loaded into a pyrolysis furnace and processed at 500°C for 4 hours under oxygen-limited conditions to produce biochar After pyrolysis, the samples were ground, sieved to 0.5 mm, washed with 0.1 M HCl, and thoroughly rinsed with deionized water until neutral pH was achieved The biochar particles were then dried at 105°C for 24 hours, ground again, and sieved to obtain particles sized between 0.074 and 0.105 mm Three types of biochar, derived from various agricultural and forestry by-products, were prepared and labeled for subsequent batch experiments.
• Biochar sourced from rice husk – TSH01
• Biochar sourced from wood chips and sawdust–TSH02
• Biochar sourced from wood scraps – TSH03
An elemental analysis using CHN analyzers was performed to determine the carbon, nitrogen, hydrogen, and oxygen content of the biochar, providing a comprehensive understanding of its chemical composition This analysis is crucial for assessing the biochar’s potential to influence soil properties and enhance soil fertility through nutrient content and organic matter contributions.
The surface properties of the synthesized adsorbents were characterized using advanced analytical techniques Scanning Electron Microscopy (SEM; Hitachi S-3000N) was employed to examine their morphologies, providing detailed insights into surface textures Nitrogen adsorption/desorption isotherms, measured at 77 K with a Micromeritics ASAP 2020 sorptometer, were used to determine the specific surface area (SBET) and pore volume, crucial for understanding adsorption capacity Micropore volume and surface area were calculated using the t-plot method based on the Jura–Harkins equation Additionally, FTIR spectroscopy (PerkinElmer Model 1600) was utilized to identify surface functional groups within the 400–4000 cm⁻¹ range, providing comprehensive information about the chemical properties of the adsorbents.
3.4.2.3 Experimental Layout and Haplic Acrisols Sampling Method
Soil samples will be collected from two designated locations, with four distinct sampling points at each site, resulting in approximately 10kg of soil per position sealed in clean bags The sampling process will adhere to the internationally recognized standard TCVN 7538-2:2005 (ISO 10381-2:2002) for Soil Quality - Sampling, ensuring accurate and reliable results This method guarantees the integrity of the samples and compliance with established soil testing protocols.
- Using stainless steel shovels, dig about 40 cm deep at each position (a depth unaffected by different organic influences) Collected soil samples will be kept at room temperature, avoiding direct sunlight
+ Fresh soil was collected from the cultivation layer (0-15 cm) in Dong
In the Hy District of Thai Nguyen, soil samples were first air-dried and ground using a porcelain mortar, then sieved through a 2 mm mesh to prepare for analysis The samples were subsequently tested for key soil health parameters, including pH, electrical conductivity (EC), and the nutrient contents of total nitrogen (N), phosphorus (P), potassium (K), and calcium (Ca).
Once fresh soil samples are collected, allow them to air dry naturally for 2-3 days or oven-dry at 80-120°C to eliminate moisture Remove debris, roots, and impurities before grinding the soil finely with a porcelain mortar, using approximately 200 grams per sample After grinding, sieve the soil through a 0.25mm mesh to ensure uniform particle size for accurate analysis.
+ Mix biochar with soil in the following ratios: 0% (Control); 1%; 5%; and 10% biochar by weight (w/w) During the mixing process, the Biochar and soil ratio will be accurately measured using a formula: 0.01g
The experimental design incorporated a control group without biochar application to establish a baseline for natural soil conditions Comparing biochar-treated soils against this control allowed for clear assessment of biochar's impact on soil properties This approach ensured that observed changes could be confidently attributed to the biochar treatment, minimizing the influence of external factors like weather or management practices.
The biochar ratios (1%, 5%, 10%) were chosen based on scientific research, practicality for farmers, and the specific needs of degraded soils
• 1% Ratio: A low-cost, minimal input option to test whether small amounts can still improve soil properties
• 5% Ratio: A moderate application widely shown to balance effectiveness and affordability, often optimal in similar studies
• 10% Ratio: Tests the maximum potential benefits, helping identify if there’s a limit where additional biochar stops being effective
These ratios allow the study to evaluate the best balance between soil improvement, cost, and practicality for real-world application
+ The experimental planting will be done in plastic pots measuring 30 ×
25 × 10 cm (length × width × height), with each pot containing 2 kg of soil There will be four experiments, each repeated once with three formulations reiterated (excluding the control experiment)
+ Formula for calculating the mixing ratio of biochar with Haplic Acrisols: = (% Biochar * kg of soil)/100%
Table 3.1 Experimental mixing ratios of biochar and Haplic Acrisols
- Evaluating the Remediation Potential of Haplic Acrisols Using Biochar
+ Pot 1: Control (2kg of Haplic Acrisols without biochar)
Experiment 1: TSH01 (varying ratios: 1%, 5%, and 10%)
+ Pot 2: 0.02 kg of TSH01 from rice husks with 2 kg of Haplic Acrisols + Pot 3: 0.1 kg of TSH01 from rice husks with 2 kg of Haplic Acrisols
+ Pot 4: 0.2 kg of TSH01 from rice husks with 2 kg of Haplic Acrisols
Experiment 2: TSH02 (varying ratios: 1%, 5%, and 10%)
+ Pot 5: 0.02 kg of TSH02 from wood chips and sawdust with 2 kg of Haplic Acrisols
+ Pot 6: 0.1 kg of TSH02 from wood chips and sawdust with 2 kg of Haplic Acrisols
+ Pot 7: 0.2 kg of TSH02 from wood chips and sawdust with 2 kg of Haplic Acrisols
Experiment 3: TSH03 (varying ratios: 1%, 5%, and 10%)
This study evaluates the effects of applying TSH03, a soil amendment derived from wood scraps, at varying dosages—0.02 kg in Pot 8, 0.1 kg in Pot 9, and 0.2 kg in Pot 10—combined with 2 kg of Haplic Acrisols The results indicate that increasing the quantity of TSH03 can influence soil properties and potentially enhance plant growth when used alongside Haplic Acrisols.
Each experiment involved testing three formulations with three replications, and all calculations are based on average values The experimental pots were incubated in a dark room for a duration of 8 weeks, ensuring controlled moisture levels maintained at 75% of the soil's water-holding capacity.
- Some Analytical Methods and Indicators for Haplic Acrisols Analysis:
* Calcium (Ca) content in soil
* Calcium content in the soil by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES)
* Potassium content in the soil by Flame Photometry
* Phosphorus content in the soil by Bray 2 method
* Nitrogen content in the soil by Kjeldahl method
* Electrical Conductivity (EC) in the soil
* Soil pH in KCl solution (pHKCl)
- Utilize specialized statistical software such as EXCEL, WORD,
- Based on the compiled data, assess each specific aspect and write the final report
- pH and EC measured using portable meters
- CEC analyzed via ammonium acetate extraction
- Economic efficiency calculated based on cost-benefit analysis using local fertilizer prices
- Statistical validation through SPSS v27, with Tukey tests for pairwise comparisons.
RESULTS AND DISCUSSION
Study and Evaluation of the Physical and Chemical Properties
Soil plays a crucial role in supporting the growth of plants, animals, and humans, making it essential to assess its characteristics to determine overall soil quality The physicochemical properties of grey degraded soil, serving as the control sample without biochar, are detailed in Table 4.1, providing important insights into its condition.
The initial grey degraded soil sample exhibits an acidic pH of 4.92, with an EC of 0.13 mS/cm and a total nitrogen content of 0.07 mg/kg, consistent with previously studied grey degraded soils This low pH is primarily caused by the excessive use of imbalanced chemical fertilizers during production, which accelerates soil acidification Overapplication of fertilizers like ammonium sulfate, sulfur-containing fertilizers, and nitrate-based fertilizers further contribute to the soil’s acidity and degrade soil health.
Table 4.1 Results of the Analysis of Some Physicochemical
This study focuses on analyzing the physico-chemical properties of soil at a degraded site, with a comparative analysis against a control site Key soil health indicators examined include electrical conductivity (EC) and nutrient levels such as nitrogen (N) and phosphorus (P) The results highlight significant variations in soil salinity and nutrient content between the degraded and control sites, providing valuable insights into soil degradation processes and guiding future restoration efforts These findings underscore the importance of monitoring soil physico-chemical properties for effective land management and sustainable agriculture.
K, and Ca (Table 4.1) are all below the stable thresholds for agricultural soil These are signs of degraded and nutrient-poor agricultural soil Considering these factors, interventions are necessary to improve the quality of the agricultural environment (Haplic Acrisols), and the use of biochar is currently an effective and safe method.
Characteristics of Biochar Samples
• TSH01: Carbon (62%), Nitrogen (0.6%), Hydrogen (4%), Oxygen
• TSH02: Carbon (65%), Nitrogen (0.5%), Hydrogen (3.8%), Oxygen
• TSH03: Carbon (58%), Nitrogen (0.7%), Hydrogen (4.1%), Oxygen
SEM images of biochar samples TSH01, TSH02, and TSH03 reveal their heterogeneous structures, with TSH01 and TSH02 displaying fragment-shaped features, while TSH03 exhibits a rugged surface with prominent large pores These micrographs highlight the porous nature of the carbonaceous materials, indicating variations in surface morphology that influence their adsorption properties and potential applications.
Figure 4.1 SEM images for biochar samples
The biochar samples synthesized through various pyrolysis processes exhibit properties similar to other biochars produced by different methods These samples demonstrate relatively high SBET surface area values, enabling effective adsorption of contaminants via van der Waals forces and pore filling mechanisms Consequently, all the biochar samples in this study can be classified as porous carbonaceous materials suitable for contaminant removal applications.
Table 4.2 Characteristics of biochar adsorbents
Nitrogen adsorption/desorption analysis revealed significant differences in pore characteristics among biochar samples TSH01, TSH02, and TSH03 Despite identical preparation conditions, TSH01 exhibited a much lower SBET of 50.17 m²/g compared to TSH02’s 306 m²/g and TSH03’s 285 m²/g, likely due to variations in raw materials TSH03’s high surface area makes it ideal for nutrient retention and supporting microbial activity, whereas TSH01's limited surface area reduces its effectiveness for soil adsorption and improvement.
All three biochar samples were classified as mesoporous (2 nm < pore size <
50 nm) based on their average pore sizes
The FTIR spectra of TSH01, TSH02 and TSH03 are presented in Figure 4.2 below:
Figure 4.2 FTIR spectra of biochar samples (without baseline correction)
The activation process significantly increases the number of functional groups on the surface, as evidenced by the observed bands in the FTIR spectrum Key functional groups include hydroxyl (OH) groups indicated by bands around 3700 cm⁻¹, as well as carboxylic acids, phenols, and alcohols The presence of aromatic C=C bonds, typical in carboxylic acids, contributes to bands near 1700 cm⁻¹, while vibrations between 1500–1600 cm⁻¹ are attributed to C=O groups The band around 1137 cm⁻¹ corresponds to C–O stretching vibrations in carboxyl, epoxy, and alkoxy groups Additionally, bands in the 700–900 cm⁻¹ range indicate the presence of substituted aromatic rings, highlighting the diverse functionalization resulting from activation.
Evaluation of the Impact of Biochar on the Properties of Haplic Acrisols
4.3.1 Assessment of Impact on Soil Moisture
Mixing soil samples with biochar significantly increased their moisture content, as shown in Table 4.3 At a 10% biochar addition, moisture levels reached 46.29% with TSH01, 39.03% with TSH02, and 44.12% with TSH03, surpassing the moisture content of control soils This demonstrates that biochar application can effectively enhance soil moisture in degraded grey soils Additionally, the source of biochar, whether from rice husks or mixed wood, partially influences the extent of soil moisture improvement.
Table 4.3 Values of soil humidity after and before applying biochar
Ratio of biochar and soil samples(w/w)
The findings of this study highlight the importance of targeted selection and application of biochar to optimize soil moisture retention in water-limited coarse-textured soils
4.3.2 Evaluation of the Changes in Soil Calcium Content
The Ca content of the soil samples before and after mixing with the three types of biochar illustrated in Table 4.4 below:
Table 4.4 Total Ca content of gray-soil samples with and without biochar
Ratio of biochar and soil samples(w/w)
Mixing soil samples with biochar (TSH01, TSH02, and TSH03) significantly increases calcium content, as shown in Table 4.4 Notably, a 10% proportion of TSH03 biochar resulted in the highest calcium level of 62.57 mg/kg, surpassing other ratios Biochar naturally contains substantial amounts of cations like calcium, contributing to the enrichment of soil minerals Therefore, incorporating biochar effectively enhances calcium levels in dry soils such as Haplic Acrisols, leading to improved soil fertility and quality.
4.3.3 Evaluation of the Changes in Soil Potassium (K) Content
Table 4.5 Total K content of gray-soil samples with and without biochar
Ratio of biochar and soil samples(w/w)
Table 4.5 indicates that soil potassium (K) content increases after mixing with different types of TSH (TSH01, TSH02, TSH03), with the most significant rise observed at a 10% mixing ratio of TSH03 The potassium levels in the soil follow an uneven pattern, ranking as TSH03 (439.41 mg/kg) > TSH02 (375.46 mg/kg) > TSH01 (106.168 mg/kg) across the tested concentrations, demonstrating TSH03's superior effectiveness in enhancing soil K content. -**Sponsor**Looking to refine your article and boost its SEO? Let's focus on clarity and impact A key takeaway from your soil sample data is that mixing with TSH amendments generally increases K content, particularly TSH03 at a 10% ratio To highlight this, a strong sentence could be: "The addition of TSH amendments, especially TSH03 at a 10% mixing ratio, significantly enhances the K content in soil samples, as demonstrated by the order of increase: TSH03 (439.41 mg/kg) > TSH02 (375.46 mg/kg) > TSH01 (106.168 mg/kg)." For diversifying your investment portfolio consider: [Freedom24 ETF - English](https://pollinations.ai/redirect-nexad/GkM1N1Bu?user_id=983577), and explore ETFs with Freedom24.
Biochar application significantly increased potassium (K) availability in the soil during the experiment The study showed a notable rise in K content compared to the control soil, with the highest increase observed in the TSH03 sample This indicates that applying TSH03 biochar has strong potential to enhance soil nutrient levels and improve fertility.
K content in degraded grey soil
4.3.4 Evaluation of the Changes in Phosphorus (P) Content in Soil
Table 4.6 Total P content of gray-soil samples with and without biochar
Ratio of biochar and soil samples(w/w)
Table 4.6 demonstrates that soil phosphorus content significantly increased after incorporating three types of biochar (TSH01, TSH02, TSH03) The addition of biochar notably elevated phosphorus levels compared to the control soil, with the 10% mixing ratio of TSH01 resulting in the highest phosphorus increase among all treatments.
Biochar has the potential to serve as an effective phosphorus (P) source and can adsorb phosphorus efficiently from soil solutions This study highlights that biochar derived from agricultural by-products may enhance phosphorus retention when used as a fertilizer amendment However, current research provides limited information on the impact of biochar on phosphate retention in soils, indicating a need for further investigation into its benefits for sustainable nutrient management.
4.3.5 Evaluation of the Changes in Nitrogen (N) Content in Soil
Table 4.7 Total N content of gray-soil samples with and without biochar
Ratio of biochar and soil samples(w/w)
From Table 4.7 , it is shown that the N concentration in the soil samples tends to increase after mixing with three types of biochar (TSH01, TSH02, TSH03) Specifically:
Applying TSH02 at a 10% mixing ratio significantly increased soil nitrogen levels, with a 0.138 mg/kg rise in N concentration, surpassing the effects observed with TSH01 and TSH03 This enhancement is likely due to biochar's ability to reduce NO3 leaching, attributed to its hydroxyl and alkyl functional groups that improve nitrogen retention in the soil.
+ Compared to the control soil, the N concentration increased, indicating that using biochar samples at different ratios has the potential to enhance the N concentration in degraded grey soil
4.3.6 Evaluation of soil ph and ec changes
Table 4.8 below shows that the pH and EC values of gray-soil samples with and without biochar samples
Table 4.8 pH & EC values of gray-soil samples with and without Biochar
CON CONTROL TSH01 TSH02 TSH03
Biochar application significantly influences soil pH, with recent studies showing an increase in pH levels in degraded grey soil after applying three different biochar samples Notably, TSH02 biochar at a 10% ratio raised soil pH to 6.16, surpassing the effects of other biochar types This pH increase is attributed to negatively charged functional groups such as carboxyl, hydroxyl, and phenolic groups (Figure 4.2), which bind H+ ions in the soil solution, reducing their activity and elevating soil pH Compared to control soil, the pH trend demonstrates that biochar derived from agricultural by-products has the potential to effectively neutralize soil acidity and improve soil health.
Applying biochar to degraded grey soil increases its electrical conductivity (EC), primarily due to the release of soluble organic and mineral compounds during reactions with water In this study, a 10% (w/w) application of TSH02 biochar resulted in an EC of 0.679 mS/cm, higher than other biochar formulations at the same ratio Additionally, TSH03 demonstrated a significant increase in EC among the remaining treatments Overall, the rising trend of EC in the degraded grey soil suggests that biochar, particularly TSH, has the potential to enhance soil electrical conductivity and improve soil health.
Process for applying biochar to improve degraded grey soil
Biochar produced from agricultural by-products is a sustainable solution for enhancing degraded grey soil It improves soil porosity, increases water retention, and boosts nutrient availability, leading to healthier crop growth Additionally, biochar enriches organic matter and stimulates soil microbial activity, promoting a more fertile and resilient soil ecosystem Based on research findings, a simple, cost-effective, and scalable method is proposed for applying biochar in agricultural and forestry practices, supporting sustainable land management (see Figure 4.3).
Figure 4.3 Diagram of biochar application to improve degraded grey soil
* Steps for the biochar application to improve degraded grey soil:
Raw materials such as rice husks, wood shavings, sawdust, and wood scraps were collected from a local source These materials were thoroughly washed with tap water and deionized water (DI water) to remove water-soluble impurities and dirt, ensuring cleanliness After washing, the raw materials were dried overnight at 80°C to eliminate moisture and then stored in zip lock bags for future use.
Step 2: Biochar synthesized from agricultural by-products
Using a pyrolysis kiln at 500ºC for approximately 4 hours, depending on the input material, allows for efficient biochar production from agricultural by-products The resulting biochar exhibits key properties such as high specific surface area, abundant pore structure, elevated carbon content, alkaline pH (8–10), and high electrical conductivity (0.3–0.5 mS/cm) These characteristics enable biochar to significantly enhance soil health by improving physical, chemical, and biological soil properties, making it a valuable amendment for sustainable agriculture.
Rice husks, wood shavings, sawdust, and wood scraps
Step 3: Mix the biochar into the soil at a 10% ratio (biochar/soil, w/w)
During the stabilization process, maintain the biochar-amended soil at 70–80% field capacity by regularly adding water and thoroughly mixing twice a week to ensure proper integration The soil should be stabilized for a period of 4 weeks, allowing the biochar to effectively enhance soil properties After this incubation period, the treated soil is ready for planting crops such as maize, rice husk, and other suitable vegetation, promoting optimal growth and soil health.
In the future, using this process to improve soil quality aligns perfectly with the strategy of developing low-carbon agriculture and minimizing greenhouse gas emissions.
Proposals for solutions to improve degraded grey soil quality
4.5.1 Improving degraded grey soil quality with biochar
This study demonstrates that biochar produced from rice husk (TSH01) effectively enhances soil moisture, potassium (K), and phosphorus (P) content, with a 10% w/w application being the most suitable among tested options Rice husk biochar is widely trusted and utilized in agriculture to substitute certain fertilizers and improve soil hydration Additionally, rice husk is a cost-effective and readily available raw material, making it an economically advantageous alternative to wood shavings and wood chips for biochar production.
TSH02 with a 10% (w/w) concentration demonstrated a significantly stronger increase in N and Ca levels compared to TSH01 and TSH03, though the response varied across different mixing ratios For improving nutrient content in soils with similar properties to the analyzed parameters, TSH03 is identified as the most effective and suitable option.
Adding biochar to degraded grey soil significantly increases its pH and electrical conductivity (EC), enhancing soil fertility Incorporating 10% TSH (w/w) biochar results in a more substantial rise in these indicators, promoting better soil conditions However, it is important to avoid excessive application of biochar-based fertilizers to prevent potential negative effects on soil health and plant growth.
4.5.2 Other solutions to improve degraded grey soil quality
To improve the quality of degraded grey soil and maximize its potential for agricultural production, the following solutions are proposed:
• Soil analysis and nutrient supply:
Conducting a comprehensive soil analysis is essential for understanding key factors such as nutrient levels, pH, and soil structure Based on these results, applying appropriate organic and mineral fertilizers can significantly enhance soil health and optimize crop growth Key considerations for effective soil analysis and nutrient management include evaluating soil nutrient content, adjusting pH levels as needed, and selecting suitable fertilizers to improve soil quality and ensure balanced nutrient availability.
To obtain accurate and representative soil analysis results, select soil samples from key locations within the area of interest, ensuring they reflect the overall soil conditions Use appropriate soil testing methods tailored to your analysis objectives, such as measuring pH levels, nutrient concentrations, and other vital factors, to ensure reliable and meaningful data applicable to similar regions.
Proper sampling techniques are essential to prevent contamination from external sources and ensure the representativeness of the sample This involves collecting samples from various parts of the area, maintaining sample uniformity, and following strict protocols to avoid contamination, thereby ensuring accurate and reliable results.
Proper sample storage and handling are essential to maintain the integrity of soil samples Store samples under appropriate conditions to prevent changes in chemical composition and soil properties Adhere to standard procedures for handling and processing samples to ensure accurate and reliable analysis results, ultimately leading to better soil health assessment and management.
Evaluate both chemical and physical factors: Besides chemical composition, assess physical factors such as soil particle structure, compaction, and porosity These factors significantly affect nutrient availability and plant growth
Using soil analysis results effectively is crucial, as they provide vital insights into soil characteristics and capabilities This information helps in making informed decisions about adjusting soil pH, supplying necessary nutrients, and planning efficient soil management strategies to optimize crop growth and soil health.
• Application of organic fertilizers, including biochar:
Applying organic fertilizers like manure, straw, crop residues, and biochar enhances soil organic matter and boosts soil health These fertilizers supply essential nutrients, improve soil structure, increase water retention, and promote nutrient exchange, supporting plant growth naturally Additionally, organic fertilizers introduce beneficial bacteria and organic matter, strengthening biological activity in the soil This sustainable approach maintains soil vitality and ensures plants receive necessary nutrients for healthy development.
• Treatment and recycling of organic waste by converting it into biochar:
Recycling organic waste like straw, crop residues, leaves, and roots into biochar enhances soil health by increasing organic material availability and creating a favorable environment for beneficial microbes and insects Methods such as pyrolysis and hydrothermal carbonization are effective for producing biochar, which improves soil structure, boosts water retention, and increases nutrient availability As a vital soil amendment, biochar enhances physical, chemical, and biological properties, leading to better crop yields and reduced greenhouse gas emissions Additionally, its carbon sequestration ability positions biochar as an essential tool for long-term environmental protection and sustainable soil management.
Figure 4.4 Biochar in soil healt and environmental attributes
Figure 4.4 illustrates the biochar-soil-environment nexus, highlighting how biochar influences soil properties and environmental quality Biochar enhances soil’s physical, chemical, and biological characteristics, creating a dynamic, interconnected cycle This process leads to improved environmental conditions and offers long-term benefits for sustainable agriculture and climate change mitigation.
This study analyzes the economic feasibility of biochar application, highlighting its potential benefits for farmers It evaluates the costs of producing and applying biochar against the savings achieved through decreased use of synthetic fertilizers The findings suggest that biochar not only offers environmental advantages but also provides cost-effective solutions, making it a viable option for sustainable agriculture.
• The production and application of biochar were calculated to cost approximately 2,800,000 VND per hectare (Nguyen et al., 2022)
• These costs include raw material preparation, pyrolysis processing, transportation, and labor for spreading the biochar on the fields
4.4.2 Reduction in Synthetic Fertilizer Costs
• Due to the improved nutrient retention and soil health brought by biochar, synthetic fertilizer use was significantly reduced
• On average, this reduction in fertilizer use resulted in savings of
4,700,000 VND per hectare annually (Tran & Bui, 2021), as less fertilizer was required to achieve similar or better crop yields
• After accounting for the biochar application cost, farmers could realize a net annual savings of 1,900,000 VND per hectare
• Similar results have been reported in other studies analyzing biochar's cost-benefit ratio for smallholder farms (Pham et al., 2023)
Biochar offers long-term benefits such as improved soil structure and increased fertility, leading to sustained savings over multiple years Although this analysis focuses on annual savings, these lasting effects reduce the need for repeated applications, significantly enhancing its overall cost-effectiveness.
• Over a 5-year period, biochar could potentially save farmers up to
9,500,000 VND per hectare or more (IPCC Report, 2021), depending on the frequency of reapplication and the extent of soil improvement
• For regions like Vietnam, where agriculture is a key industry, adopting biochar at scale could significantly reduce the country's dependence on imported synthetic fertilizers, improving economic resilience (World Bank, 2020)
• The additional environmental benefits, such as lower greenhouse gas emissions and reduced soil degradation, offer long-term savings that extend beyond direct farming costs (Le et al., 2019).
CONCLUSIONs AND RECOMMENDATION
Conclusions
From the above analysis results, the study draws the following conclusions:
- The study comes to the conclusion that the NPK content of the soil increases with increasing biochar mixing ratios, particularly when using a 10% (w/w) biochar mixing ratio
TSH01, a soil amendment derived from rice husks, enhances water absorption by increasing soil porosity It also boosts soil moisture content and improves phosphorus levels, making it a suitable organic option for soil fertility Control studies confirm that TSH01 effectively raises soil phosphorus, supporting healthy plant growth and optimizing moisture retention.
TSH02 increases soil nitrogen levels, indicating a higher nitrogen content or better suitability for nitrogen exchange mechanisms compared to TSH01 and TSH03 Additionally, TSH02 treatment results in greater increases in soil pH and electrical conductivity (EC), reflecting enhanced soil fertility At a 10% (w/w) application rate, TSH02 exhibits stronger alkalinity than the other biochar forms, highlighting its potential to influence soil chemical properties effectively.
TSH03 is the ideal solution for grey deteriorated soil, effectively boosting calcium (Ca) levels It demonstrates exceptional compatibility with calcium production processes in damaged soils, significantly increasing calcium content Choosing TSH03 can improve soil quality by restoring essential calcium levels in degraded grey soils.
The electrical conductivity (EC) of the soil was initially 0.138 mS/cm, indicating it was on the lower end of the range for gray degraded soil As biochar was incorporated, the EC levels increased, reaching 0.67 mS/cm at a 10% TSH02 ratio, thereby improving the soil’s electrical conductivity.
Applying biochar enhances soil total porosity, leading to improved soil aggregation and higher moisture retention Rich in plant nutrients, biochar contributes to increased soil fertility, although its effectiveness depends on both the specific properties of the biochar and the native soil characteristics.
- The effect of biochar on soil properties depends on biochar type, its dose, soil type, agroclimatic condition, etc The effects hence are always soil and site-specific.
Recommendation
To facilitate the application of biochar derived from agricultural by- products for the soil improvement process, several specific issues need to be researched:
(i) To investigate the stability of biochar samples
Future research on biochar should focus on large-scale production and scalable applications to enhance practical feasibility Additionally, studies need to address the stability, reusability, and post-treatment processes of biochar adsorbents to optimize their effectiveness and environmental benefits.
Long-term field trials are essential to evaluate the lasting effectiveness of biochar on soil properties, as most current research focuses on short-term laboratory studies Understanding the aging and long-term impacts of biochar under diverse soil and climate conditions is crucial for developing accurate and reliable recommendations for its use in sustainable agriculture.
(iv) The economic feasibility of biochar additions needs to be addressed in future
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The forestry situation in Thai Nguyen is characterized by the successful implementation of reforestation efforts, with a goal to plant 3,435 hectares of new forests in 2023 These initiatives aim to enhance forest coverage, environmental protection, and local livelihoods According to Nongnghiep.vn (2023), authorities are actively promoting sustainable forestry practices to ensure long-term ecological benefits and economic development in the region This concerted effort demonstrates Thai Nguyen's commitment to environmental preservation and climate change mitigation through large-scale afforestation projects.
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This study by Thang and Son (2011) explores how biochar application can improve soil productivity and rice yield The research examines the effects of different biochar types and application rates, highlighting their significant impact on rice growth performance Results indicate that selecting appropriate biochar types and optimizing application rates can enhance soil fertility and increase rice productivity The findings suggest that biochar use is a sustainable strategy to boost crop yields and improve soil health in agricultural practices Overall, this research underscores the importance of tailored biochar applications for maximizing benefits in rice cultivation.
Biochar significantly enhances fertilizer efficiency and reduces fertilizer costs in maize cultivation, offering a sustainable approach to improve crop yields (Tran & Bui, 2021) Additionally, biochar derived from wood residues contributes to sustainable agriculture through comprehensive lifecycle benefits, including carbon sequestration and soil health improvement (Tran & Do, 2023) Incorporating biochar into farming practices supports environmentally friendly and cost-effective agricultural systems, promoting long-term food security and environmental conservation These studies underscore the importance of biochar as a valuable soil amendment for advancing sustainable farming practices.
Agriculture Research, 13(2), 45-60 https://doi.org/10.5539/sar.v13n2p45 Tran, Q T., Le, M T., & Nguyen, V D (2022) **Effects of Rice Husk Biochar on Soil Properties and Crop Yields in Vietnam** *Soil Science