A review on the impact of biochar applications on soil health and fertility, plant growth, and food security: advancing agricultural sustainability

Chapter 1 - Mechanisms of the phytomicrobiome for enhancing soil fertility and health

Soil health management and increase crop productivity are challenging issues for researchers and scientists. Many research publications have given multiple technological solutions for improving soil health and crop productivity but main problem is sustainability of those technologies under field condition and different agro-climatic zone. Due to the random industrialization, deforestation, mining and other environmental factor reduce soil fertility and human health. Many alternative options e.g., crop rotation, green manuring, integrated farming, biofertilizer (plant-growth-promoting microorganism, microbial consortium of rhizosphere soils), and vermicomposting are available for adapting and improving the soil heath and crop productivity by farmers. Recent trends of new research dimension for sustainable agriculture, endophytic microbes and its consortium is one of the better alternative for increasing crop productivity, soil health and fertility management. However, current trends are focuses on the endophytic microbes, which are present mostly in all plant species. Endophytic microbes are isolated from plant parts-root, shoot, leaf, flower and seeds which have very potential ability of plant growth promotion and bio-controlling agent for enhancing plant growth and development. Mostly plant endophytes showed multi-dimensional (synergistic, mutualistic, symbiotic etc.) interactions within the host plants. It promotes the plant growth, protects from pathogen, and induces resistance against biotic and abiotic environmental stresses, and improves the soil fertility. Till date, most of the scientific research has been done on assuming that interaction of plant endophytes with the host is similar like the plant-growth-promoting microorganism (PGPM). It would be very interesting to explore the functional properties of plant endophytes to modulate the essential gene expression during biotic and abiotic stresses. Endophytes have the ability to induce the soil fertility by improving soil essential nutrient, enzymatic activity and influence the other physiochemical property. In this study, we have discussed details about functional properties of plant endophytes and their mechanism for enhancing plant productivity and soil health and fertility management under climate-resilient agricultural practices. Our main objective is to promote and explore the beneficial plant endophytes for enhancing sustainable agricultural productivity.

Soil, a natural four‐dimensional body at the atmosphere–lithosphere interface, is organic‐carbon‐mediated realm in which solid, liquid, and gaseous phases interact at a range of scales and generate numerous ecosystem goods and services. Soil organic carbon (SOC) strongly impacts soil quality, functionality and health. Terms soil quality and soil health should not be used interchangeable. Soil quality is related to what it does (functions), whereas soil health treats soil as a living biological entity that affects plant health. Through plant growth, soil health is also connected with the health of animals, humans, and ecosystems within its domain. Through supply of macro‐ and micronutrients, soil health, mediated bySOCdynamics is a strong determinant of global food and nutritional security. Soil C pool consists of two related but distinct components:SOCand soil inorganic C (SIC). TheSICpool comprises of primary and secondary carbonates, and the latter consists of calcitic (no net sequestration of atmosphericCO2) and silicatic (net sequestration). WhileSOCis highly dynamic, its mean residence time depends on the degree of protection (physical, chemical, biological, and ecological) within the soil matrix. Formation of stable microaggregates and of organo–mineral complexes can protectSOCagainst microbial processes for millennia. In addition to formation of silicatic type of secondary carbonates, leaching of bicarbonates into the subsoil or shallow water table is also an important mechanism of sequestration ofCO2asSIC. Numerous soil functions and ecosystem services depend onSOCand its dynamics. Improvements in soil health, along with increase in availability of water and nutrients, increases soil's resilience against extreme climate events (e.g., drought, heat wave) and imparts disease‐suppressive attributes. Enhancing and sustaining soil health is also pertinent to advancing Sustainable Development Goals of the U.N. such as alleviating poverty, reducing hunger, improving health, and promoting economic development.

Chapter 16 - Legume-based inter-cropping to achieve the crop, soil, and environmental health security

Extensive application of agrochemicals for crop production and protection has negatively affected soil health, crop productivity, and the environment. Organic amendments have been proposed as an efficient alternative for enhancing soil and plant health. Vermicompost amendment offers a sustainable approach to plant nutrition, improving soil health and fertility. This review aims to provide key insights into the potential of vermicompost to boost crop production and protect crops from biotic and abiotic stresses without harming the environment. The role played by earthworms in improving organic matter decomposition, soil fertility, and soil microorganisms’ activity is also discussed here. The value of vermicompost is its promotion of plant growth based on its enrichment with all essential nutrients, beneficial microbes, and plant growth hormones. This review analyzes how vermicompost regulates plant growth and its role in mitigating abiotic stresses such as soil salinity and drought, as well as biotic stresses such as diseases and insect pests attack. The beneficial effects of hormones and humic substances present in vermicompost are also discussed in this review. In fact, due to its properties, vermicompost can be a good substitute for chemical fertilizers and pesticides and its usage could contribute to producing healthy, contaminant-free food for the growing population without negatively affecting the environment.

The world population is increasing to the 7 billion marks and until the mid-2030s, the planet can expect to shoulder annual additions of 50–70 million more peoples leading to an issue of poverty, food security and access to fertile and healthy soils. Crop productivity, soil fertility and health are continuously declining due to removal of essential plant nutrients from the soils under cereals-based system in the current changing climate scenario. Cereals (wheat, maize, rice etc.) crops provide humankind with more nourishment than any other food class and nearly half of the total caloric requirement globally. As cereals are exhaustive (decline soil fertility) crops and therefore their continuous growth without balanced nutrients management decline crop productivity, soil fertility and soil health. Sustainable soil management (SSM) practices not only increase crop productivity but also improve soil fertility, health and sustainability. Widespread adoption of SSM practices generates multiple socio-economic benefits for both smallholder farmers and large-scale agricultural producers. We concluded from the review that integrated nutrients management (INM) improve soil health for sustained crop productivity in cereal based system. The concept of INM is the combined application of chemical fertilizers [nitrogenous fertilizers (urea, ammonium sulphate etc.), phosphatic fertilizers (Di-ammonium phosphate, single super phosphate etc.), and potash fertilizers (sulphate of potash, muriate of potash etc.) zinc etc.) plus incorporation of different organic matter sources [(1) animal-based sources (poultry manure, cattle manure, sheep manure, goat manure etc.) and (2) plant-based sources e.g. vegetables residues (onion, garlic etc.), cereals residues (wheat, maize, rice etc.), legumes/pulses residues (chickpea, faba bean, mungbean, cowpea etc.) and tree residues (peach, pepper mulberry etc.)] into the soil along with application of biofertilizers (beneficial microbes) improve soil fertility and health, crop growth and yield, growers income and sustainability. We concluded that INM practices which are one of the best SSM practices are recommended in exhaustive cereal-based system to decrease soil degradation due to nutrients losses and increase soil and crop productivity.

Maharashtra is one of India’s most important agricultural states, with diverse agro-climatic zones ranging from high-rainfall Konkan to drought-prone Marathwada and Vidarbha. The state is dominated by Vertisols (deep black cotton soils) and associated Inceptisols and Entisols, supporting major crops such as cotton, soybean, sugarcane, pulses and cereals. Recent assessments indicate that soil fertility, soil quality and soil health in many parts of Maharashtra are under stress due to imbalanced fertilization, declining soil organic carbon (SOC), intensive tillage, residue removal and climate variability. Soil fertility studies in Latur, Beed, Nashik, Yavatmal and Khandesh regions report widespread deficiencies of available nitrogen and phosphorus, generally adequate to high potassium, emerging secondary nutrient (especially sulphur) limitations and serious micronutrient constraints, notably zinc and iron.In parallel, soil quality evaluations using soil quality indices (SQI) and SOC stock assessments in watersheds and micro-watersheds of Kolhapur, Morna and Khandesh highlight spatial variability in physical (bulk density, structure), chemical (pH, EC, nutrients) and biological properties across land uses and cropping systems. At the state level, Maharashtra has recently completed soil spectral mapping of its entire area, enabling village-level soil health information, while national Soil Health Card data show widespread N and organic carbon deficiencies in Indian soils, including Maharashtra.This review synthesizes available information on soil fertility status, soil quality assessment and soil health considerations in Maharashtra. It clarifies conceptual distinctions between soil fertility, quality and health, summarises key indicators and methodologies, and discusses major drivers of degradation. Finally, it outlines integrated management options—balanced nutrient use, organic matter management, conservation agriculture, biochar, and policy initiatives—that can enhance soil fertility and health for sustainable, climate-resilient agriculture in the state.

Soil and water are the two critical natural resource components that support healthy agricultural systems. In a period marked by a growing global population, the link between soil health and food security becomes crucial for sustainable development and building resilient agricultural systems. Soil, a vital natural resource, is pivotal in supporting plant growth by supplying essential nutrients and offering mechanical support. It encompasses the physical, chemical, and biological attributes that collectively dictate the effective and efficient functioning of the soil. Within agroecosystems, soil undergoes manipulation through processes like input addition, nutrient extraction, alterations in water balance, and microbial activity, influencing various properties. However, in recent decades, severe deterioration in soil health has been reported across global agricultural production systems. The adoption of high-input responsive high-yielding crop varieties coupled with subsidized chemical inputs to meet growing global food security challenges has resulted in the misuse and abuse of these inputs thereby damaging physical, chemical, and biological soil health. As per the surveys conducted across India, most of the soils are reported to be deficient in essential micronutrients. Recognizing the global implications of soil health on food security underscores the necessity for international collaboration, informed policies, research, and technology investments. This articlecovers the components, indicators, and sustainable soil health management strategies. The objective is to enhance soil health, ultimately contributing to sustainable global food security by ensuring the productivity and resilience of agricultural systems. The comprehensive exploration of these aspects underscores the need for a holistic approach to address the challenges associated with soil health on a global scale.

Rapid urban expansion and a booming population are placing immense pressure on our agricultural systems, leading to detrimental impacts on soil fertility and overall health. Due to the extensive use of agrochemicals in agriculture, the necessity to meet the expanding demand for food has also resulted in unsustainable farming practices. Around the world, biochar, a multipurpose carbonaceous material, is being used to concurrently solve issues with enhancing soil fertility, plant growth, and development under both normal and stressful circumstances. It improves water retention, fosters nutrient absorption, and promotes microbial activity, creating a fertile environment that supports sustainable and resilient agriculture. Additionally, biochar acts as a carbon sink, contributing to long-term carbon sequestration and mitigating climate change impacts. The major benefit of biochar is that it helps the adsorption process with its highly porous structures and different functional groups. Understanding the elements involved in biochar formation that determine its characteristics and adsorptive capacity is necessary to assure the viability of biochar in terms of plant productivity and soil health, particularly biological activity in soil. This paper focuses on the development, composition, and effects of biochar on soil fertility and health, and crop productivity.

Soil health and soil security are intrinsically interconnected with food and nutrition security. Hence, their improvement is necessary for a normal functioning of terrestrial ecosystems, including but not limited to increasing biodiversity and crop productivity and improving people’s livelihoods. This chapter reviews the soil fertility status across various agro-ecological or geographic regions of Nepal, soil-related constraints to crop production, factors affecting soil fertility decline, improved soil management practices, soil-related policies and strategies, and contribution of soil to food and nutrition security in the country. Comparisons with south Asian literature are also made wherever relevant. Soils show spatial variability across agro-ecological or geographic regions. Soils across hills and mountains are light-textured, shallow, and susceptible to erosion while low-lying areas including Terai have heavy textured soils with greater depth, and prone to flooding. Majority of the soils in the country are acidic, low in organic carbon and total nitrogen, and deficient in zinc, boron, and molybdenum. Soil fertility is in declining trend mainly due to soil nutrient mining, depletion of soil organic matter, soil erosion in hills and mountains, and inappropriate use of chemical fertilizers in Terai region. Long-term cropping systems experiments conducted across research centers and farmers’ fields have indicated that integrated nutrient management with organic inputs and inorganic fertilizers is necessary for maintaining soil nutrient balance and enhancing productivity, profitability, and sustainability of cropping systems. The contribution of soil to food and nutrition security is discussed in relation to the importance of improved soil management practices including the use of organic inputs (manures, compost, residues), inorganic fertilizers, legumes in crop rotation, green manures, cover crops, and mulching, in-situ manuring, strip cropping, hedgerow/alley cropping, and practicing reduced or minimum tillage within the framework of integrated plant nutrient management. Improving soil information systems and site-specific nutrient management using digital technologies such as digital soil maps, mobile soil testing labs, and Nutrient Expert-based site-specific nutrient recommendations are also discussed. The chapter also highlights policy implications and recommendations for increasing food security through maintaining soil health and soil security and achieving various SDGs, in particular SDG #2 (end hunger, achieve food security and improve nutrition), #6 (water quality), #13 (climate action), and #15 (life on land) in Nepal.KeywordsDigital soil mapFertilizer recommendationFood securityNutrient managementSoil management practices

Climate change and soil health are intertwined complex processes that affect each other. The aim of this review was to find out the impact of climate change on soil health, its implication on food security and human welfare across the globe. The study found out that soil health is affected by land use practices and several anthropogenic activities carried out on landscapes; climate change and variability. Soil health also contributes to soil water retention, crop productivity, households’ food and income security culminating into a large contribution towards achieving sustainable development goals across the globe. Soil components affect climate and climate affects soil health and human wellbeing. The review article concluded that climate change and soil health are complex and intertwined multidisciplinary processes that require multidisciplinary approaches for better understanding and improvement of crop production. Appropriate climate smart agricultural practices are recommended to enhance soil health and mitigate and adapt to the changing climate for the improved farmers’ income, food security and human wellbeing across the globe.

In modern agriculture, ensuring soil health and effective fertility management are paramount for sustainable crop production and environmental stewardship. This review article comprehensively explores a spectrum of strategies aimed at enhancing soil health and fertility management within the context of sustainable agriculture. Beginning with an overview of the pivotal role soil health plays in agricultural systems, the review meticulously examines the significance of adopting sound soil fertility management practices to sustain soil productivity while mitigating adverse environmental impacts. Traditional and innovative approaches to soil management are thoroughly discussed, encompassing a range of practices such as organic amendments, cover cropping, crop rotation, reduced tillage, and integrated nutrient management. These practices, deeply rooted in agricultural traditions, are shown to enhance soil structure, foster nutrient cycling, and promote beneficial soil microbial communities, thereby contributing to long-term soil health and productivity. Furthermore, the review elucidates emerging technologies and methodologies that hold promise for revolutionizing soil health and fertility management in sustainable farming systems. Precision agriculture techniques leveraging GPS, remote sensing, and data analytics are highlighted for their potential to optimize resource use and improve crop management practices. Biochar application, a burgeoning area of research, is explored for its ability to enhance soil fertility, sequester carbon, and improve soil water retention. Additionally, manipulation of the soil microbiome through innovative techniques presents exciting opportunities for enhancing soil health and resilience, the review underscores the importance of continued research, education, and policy support in promoting sustainable soil management practices. Recommendations for future research directions are provided, emphasizing the need for interdisciplinary collaborations, long-term field studies, and farmer participatory research. Practical implications for farmers and policymakers are also delineated, emphasizing the imperative of adopting holistic approaches to soil management that integrate traditional wisdom with cutting-edge technologies. By embracing sustainable soil management practices, farmers and policymakers can safeguard soil health, enhance agricultural productivity, and ensure the long-term sustainability of our food systems and environment.

Soil health underpins ecosystem services like food security and therefore underpins human health. Poor soil health is a global problem which is hindering attempts to deliver the UN’s Sustainable Development Goals. We focus on goals 3 (human health), 13 (climate change) which are intimately linked to goal 15 (soil health). Soil health is arguably most fragile in regions such as sub-Saharan Africa (SSA) where aged soils are characterised by poor nutrient and water holding capacity, and are largely deficient in micronutrients such as Zinc. Poor soil health coupled with the largely cereal-based diets can mean that micronutrient malnutrition is high in the region. In sub-Saharan Africa, where much of the population is too poor to purchase mineral supplements, poor soil health (SDG15) can therefore negatively impact on human health (SDG3). We surveyed 3661 school children aged 13–15 in three African countries, Ghana, South Africa and Zimbabwe, for their ‘Attitudes, Behaviours and Competencies’ of soil, which we termed ‘ABC’. The ‘ABC’ survey results showed significant soil illiteracy. The survey showed that although students were generally equipped with a good attitude to (overall 52% positive) and behaviour towards soil (overall 60% engagement), they had little competency as to how to improve soil health (overall 23% knowledge). For example, less than 35% of respondents across all countries know that soil is living. Less than 13% of students are aware of the important role of soil in climate change mitigation. We believe that these two knowledge gaps must be addressed for Generation Z to understand the important linkages between climate change, soil and human health. We propose a hands-on ‘ethics of care’ approach to engage society with soil, piggybacking on existing climate change educational resources by building terrariums with living soil can empower children to learn about soil, plant, human and planetary health. The future of food security depends on Generation Z having soil literacy. Our survey clearly shows that students who think farming is a good way to make money have significantly higher levels of overall soil literacy. We propose that the future of human health depends on soil literacy.

Soil microbial dynamics are the backbone of sustainable agriculture, fostering soil health, fertility, and ecosystem resilience. These practices cultivate a thriving soil microbial community, boosting agricultural productivity and soil fertility. Promoting diverse microbial interactions is vital for maintaining a healthy soil ecosystem, supporting nutrient cycling, disease suppression, and overall soil fertility. Microbial by-products play a crucial role in soil aggregation, influencing soil structure, water dynamics, and aeration, impacting plant growth and nutrient cycling. Nitrogen fixation, a vital biological process, transforms atmospheric nitrogen into a plant-usable form, enriching soil fertility and quality. Mycorrhizal symbiosis, a remarkable mutualistic interaction between fungi and plants, promotes nutrient uptake, soil development, and sustainable agricultural practices. Soil health improvement is a comprehensive approach that addresses various aspects of soil management, promoting sustainable agriculture, ecosystem resilience, and long-term soil health. Organic matter addition, crop rotation, and diversity are integral components of sustainable agriculture, fostering a healthy and dynamic soil ecosystem. Reduced tillage, cover cropping, and effective nutrient management optimize soil health, while water management and erosion control ensure sustainable agricultural practices. Community involvement and precision agriculture are crucial for advancing sustainable soil management, with carbon sequestration being a vital strategy for addressing climate change and enhancing soil health.

Biochar produced from pyrolysis of biomass such as wood, canopy, animal manure, and agricultural waste is recognized for its stability and for being a benefactor of soil health and plant growth. Its application in forestry is an area with growing research interest due to its ability to enhance soil physicochemical properties, including structure, water retention, and nutrient availability, thereby boosting plant growth, drought tolerance, and resistance to pests and diseases. However, the effectiveness of biochar varies based on factors like biochar type, application rate, soil type, and tree species. Potential risks associated with biochar use include nutrient immobilization, increased pH in alkaline soils, and enhanced leaching of toxic elements. Despite its promise, challenges such as knowledge gaps, lack of site-specific studies, and concerns of economic viability hinder widespread adoption of biochar in forestry. This qualitative review compiles over 150 published works from the past two decades on biochar application in forestry. It assesses the impacts of biochar on soil health and tree crops, highlighting its potential to improve soil fertility and promote tree growth. The review identifies significant findings, such as the positive influence of biochar on soil and plant health and outlines existing knowledge gaps that need addressing. By synthesizing current research, the review proposes future directions to optimize biochar use in sustainable forestry management, emphasizing the need for tailored approaches and economic assessments to facilitate broader adoption. The findings underscore the potential role of biochar in enhancing forestry practices while calling for further studies to resolve uncertainties and improve its practical implementation.Graphical