Keywords

1 Introduction

Two most significant and tough challenges being faced by our society, are to feed the continuously rising populace and to evade the change of climate (Fahad et al. 2019, 2020, 2021, 2022). To diminish the effect of utilization of more land on various ecosystem amenities, the scientists must enormously focus on the eco-friendly and good approaches which are sustainable for our agriculture (Kolton et al. 2017; Shah et al. 2022; Al-Zahrani et al. 2022). The sustainability of agriculture is at stake due to various factors which are deteriorating the soil properties and soil health including soilborne diseases (Shaaban et al. 2018; Toju et al. 2018; Naz et al. 2021a; Bamagoos et al. 2021).

Healthy soil can efficiently improve the plant health and production while soilborne diseases are majorly affecting the soil health as well as quality production of food and feed (Yang et al. 2019; Riaz et al. 2021). The repeated cultivation of the same crop is known to deteriorate the soil physico-chemical properties and its nutrient status which can further worsen the soil for succeeding crop productivity and cause soil sickness (Wang et al. 2019; Liu et al. 2019; Zia et al. 2021). Seedling blight, damping-off, seed and root rots are the most communal soilborne diseases in plants which are particularly being instigated by Rhizoctonia solani and Pythium spp., causing significant crop yield losses for instance eggplant, cucumber, melon, pepper, corn, potato and tomato (Fischer and Glaser 2012; Nikraftar et al. 2013; Jaiswal et al. 2014).

Farmers usually rely on the use of certain chemicals and fungicides to eliminate the pathogens; however, these chemicals and fungicides may damage the plants and the beneficial microflora, besides being expensive (Naz et al. 2018; Jaiswal et al. 2019). Thus, control of soil borne pathogens is the essential step for preserving soil health and may be supportive for sustainable soil management to strengthen the agriculture (Xiang et al. 2019).

Consequently, there is a need to find the non-chemical, alternative approaches to reduce the incidence of soilborne diseases. One developing method that holds potential for eradicating the pathogens causing soilborne diseases is the addition of biochar which has fascinated extensive consideration owing to its key role in improving soil (Jaiswal et al. 2019). Biochar, the compact co-product of biomass pyrolysis, has increased significant research and profitable interest over the past time for a variety of reasons comprising increased soil fertility status (Frenkel et al. 2017; Ibad et al. 2022; Irfan et al. 2021; Khadim et al. 2021a, b; Khan et al. 2021; Khatun et al. 2021; Muhammad et al. 2022; Subhan et al. 2020; Tariq et al. 2018; Wiqar et al. 2022; Wu et al. 2020; Wu et al. 2019; Xue et al. 2022), pollutant fixation (Ho et al. 2017), improved plant efficiency (Ahmed et al. 2017). Soil amendments with biochar applications has been reported to increase tomato, maize, pepper, soybean and wheat plant growth and yield attributes (Graber et al. 2010; Islami et al. 2011; Alburquerque et al. 2013; Egamberdieva et al. 2016).

Moreover, the exogenous treatments of plants with biochar have also reduced the incidence of soilborne diseases by inducing ISR against fungal phytopathogens (Elad et al. 2011) including Botrytis cinerea (Mehari et al. 2015), Fusarium oxysporum in tomato (Akhter et al. 2016) R. solani in cucumber (Jaiswal et al. 2014). Hence, the biochar application has mitigated the harmful effects of soil reaction by adjusting the soil microflora (Wang et al. 2020) and have revealed the potential proficiency to subdue the soilborne plant diseases (Beesley et al. 2011). Meeting the twin challenges of rising food call and climate alteration, it is imperious to take environmental performs for maintainable farming.

Various studies have described that biochar applications also have impending role for modifying climate change by lasting reclamation of carbon and inducing greenhouse gas changes in soil, and biochar treatments has been recommended as an active countermeasure to lessen emissions of nitrous oxide and methane (Kolton et al. 2017). The biochar treatments have increased leaching of nutrients and supplementation for better plant growth (Xiang et al. 2019) and biochar adjusted soils had higher cation exchange, water holding, pH, larger surface area and lower soil bulk density, compared with the unamended soils (Enders et al. 2012).

2 Biochar to Improve Soil Health

Growth and expansion into biochar, the addition of charcoal to soil, has been growing significantly over the last few decades. As a consequence of rising alarm over worldwide climate variation caused by synthetic, anthropogenic greenhouse gas releases, there is a global effort to move from a petro economy powered by fossil carbon to a budget driven by renewable energy assets, containing biomass. Biochar is a dense by-product of biomass formed by pyrolysis or by higher temperatures about 250 °C, under limited supply of or in the whole absenteeism of air (Mao et al. 2012). Being an exothermic procedure, pyrolysis of biomass gathers more energy than is keen in the heating procedure (Murakami et al. 2007). The gaseous and liquid co-products are used for energy or chemicals, while the biochar is useful to the soil.

Biochar is trumped up of vital elements for instance hydrogen, carbon, nitrogen, sulfur and oxygen as well as reserves in the ash portion. Biochar is highly spongy, black and finely grained, with light mass, enormous surface area and pH, all of which have a progressive influence on its use to soil. The raw material (biomass) used and handling parameters grasp the properties of the biochar.

Wood chips, cow manure, grass, wheat straw, casava rhizome and rice husk are being used as raw resources by pyrolysis technology to make biochar (Ronsse et al. 2013). Various other materials including agronomic wastes (husks, peels, bark, straw, sawdust, seeds bagasse, wood chunks, corn cobs and stalks, urban waste and industrial wastes and urban/civic wastes (Kameyama et al. 2016) have been expansively utilized, therefore also attaining waste managing through its manufacture and usage (Woolf et al. 2010). The biomass utilized for the manufacture of biochar is chiefly composed of hemicellulose, cellulose and lignin polymers (Sullivan and Ball 2012). Between these, cellulose has been originated to be the chief constituent of maximum plant-derived biomasses, but lignin is also imperative in woody biomass.

Essentially, biochar additions to soil have been displayed to expressively increase soil nutrient preservation and accessibility to vegetation, and crop output (McCormack et al. 2019). The modification of topsoil with biochar has been stated to increase plant growth and yield indices. Furthermore, biochar grips the ability as an appropriate carrier of microbial inoculants to expand plant growth. The biochar uses improved water holding capacity, soil cation exchange capacity and organic material.

3 Improvement of Soil Microflora and Plant Growth by Biochar Amendment

Various studies have been reported in displaying the ability of biochar to improve the soil microflora, resulting in greater accretion of carbon in soil. Also adsorbing nutrients organic constituents, and gases, biochar is expected to offer a locale for actinomycetes, bacteria and fungi (Thies and Rillig 2012). The improvement of water holding after biochar utilization in soil has been well known (Busscher et al. 2010) and this could disturb the microbial inhabitants of soil. Numerous interpretations stated that phosphate solubilizing fungi in combination with biochar improved growth and yield attributes of Glycine max and Vigna radiate plants, compared to untreated control (Saxena et al. 2017). The usage of biochar enhanced mycorrhizal growth because this association has provided the best conditions to plant roots for more colonization (Solaiman et al. 2010).

Biochar applications are also reported in Phaseolus vulgaris to improve the biological N2 fixation largely due to larger accessibility of micronutrients to plants. Moreover, biochar reduced leaching of NH4+ by supporting it in the apparent soil where it was existing for plant approval (Lehmann et al. 2003). Mycorrhizal fungi were frequently involved in crop administration approaches as they were broadly utilized as additions for soil inoculum (Schwartz et al. 2006). The bacterial and fungal hyphae that inhabit the biochar bits (or other porous materials) may be threatened from soil predators such as Collembola, mites, nematodes and protozoans (Ezawa et al. 2002). Biochar can upsurge the cost of unharvested crop yields and confirm the efficient plant growth (Oguntunde et al. 2004). Biochar applications to the soil, has significantly enhanced the rice yield with small P availability (Silber et al. 2010).

Several properties are interrelated and may turn synergistically to enlarge crop output. The straight helpful properties of biochar mixing for the suitability of nutrients are largely because of the higher content of phosphorus, zinc, and potassium accessibility and, to a reduced level of copper and calcium. Very few studies have examined the ability for altering biochar in soil to influence plant competition against pathogens. Alterations regarding charcoal additions reported to have negative impact on the proliferation of phytopathogens (Matsubara et al. 2002). It has been reported that the powdered hardwood when used to make biochar and supplemented to asparagus grown soil exhibited a prominent decrease in root lesions instigated by F. asparagi, F. oxysporum and F. proliferatum compared to control soil where biochar was not added (Novak et al. 2009).

4 Effects of Biochar Application on Plant Diseases

Few studies have described the strength of biochar soil adjustment against soilborne diseases to influence the level of plant resistance. The charcoal based biochar application has been documented for their suppressive effects against soilborne Fusarium sp. (Matsubara et al. 2002; Elmer and Pignatello 2011). The suppression of soilborne pathogens owing to biochar applications is dependent upon several mechanisms, including: (i) nutrient solubilization and distribution to plant for improving growth and resisting pathogenic microflora (ii) improving the defense system of soil microbes against phytopathogens via enhancing antibiotic production and parasitism (iii) presence of organic compounds in biochar compositions result in propagation of resilient communities of beneficial microbes; (iv) the elicitors released by biochar applications may persuade the systemic defense pathways (Atkinson et al. 2010; Frenkel et al. 2017).

Microorganisms which cause reduction in toxic organic pollutants are usually considered extra resistant to a diversity of lethal organic compounds as well as pathogenic attacks. Moreover, volatile compounds and antibiotic producers are also found to be resilient to an assembly of antibiotics (Ahmed et al. 2017). Microorganisms producing antibiotic compounds have been reported in biochar-amended soil for instance Pseudomonas aeruginosa and Pseudomonas mendocina (Graber et al. 2010). The prospect that biochar encourages plant systemic resistance responses against disease microorganisms has been thoughtful in numerous different systems linking foliar pathogens. The severity of diseases triggered by biotrophic (Oidiopsis sicula) and necrotrophic (Botrytis cinerea) pathogens in tomato and pepper (Graber et al. 2010) was sigificantly reduced in biochar-amended treatments. Biochar soil adjustments in strawberry plants additionally resulted in destruction of pathogens including Podosphaera aphanis, B. cinerea, and Colletotrichum acutatum (Meller Harel et al. 2012).

Induced resistance in plants, was found to be effective against a wide range of pathogens and parasites comprising fungi, viruses, bacteria and nematodes. ISR is a functional state of enhanced defensive capability provoked by exact stimuli, whereby the plant’s innate defenses are potentiated against succeeding diseases (Vallad and Goodman 2004).

4.1 Biochar to Control of Soilborne Phytopathogens

The concerns as food safety, decreasing soil richness, profitability and climate variation are the active components after the introduction of new skills or new agricultural schemes. The alteration of soils for their stress alleviation goals at dipping the danger of pollutant handover to entities in closeness. Biochar can aid as a standard select for this drive because its basis is biological and it might be applied directly as pretreatment to soils (Beesley et al. 2011). There are dual features which mark biochar adjustment higher to other organic supplies: the main is the high permanency against deterioration, with the aim of persisting in soil for lengthier times showing enduring helps to soil and the another is having extra competence to keep the nutrients available. Biochar adjustment increases the soil quality by increasing the number of beneficial microbes, improving pH, cation-exchange capacity and moisture-holding ability (Mensah and Frimpong 2018).

The mixing of biochar to the soil has exposed the increase in accessibility of prime cations as well as in absorptions of nitrogen and phosphorus (Lehmann et al. 2003). Various studies have revealed the dominance of biochar in controlling phytopathogens. Biochar has been found to be very suppressive against soilborne (R. solani and species of Phytophthora and Fusarium) as well as airborne pathogens (powdery mildew and B. cinerea) (Bonanomi et al. 2015). The claim of the biochar resulting from citrus wood was proficient of decreasing the incidence of air-borne gray mold in chili caused by B. cinerea. However, the available data is very scarce regarding the disease suppressive potential of biochar against soilborne pathogens (Elmer and Pignatello 2011).

Additionally, biochar application was established to lessen plant diseases by influencing systemic resistance in plants in contradiction of different fungal pathogens, containing R. solani in cucumber, F. oxysporum and B. cinerea in tomato (Azeem et al. 2021). Biochar applications alone as well as in combination with mycorrhizal fungi to asparagus soils, has not only increased the asparagus biomass but also decreased the root rot infections caused by Fusarium (Elmer and Pignatello 2011; Thies and Rillig 2012; Akhter et al. 2016); Ogawa (2009) stated the usage of biochar and biochar edited manures for monitoring the diseases caused by fungi and bacteria in topsoil.

4.2 Role of Biochar in Induced Resistance Against Soilborne Phytopathogens

Generally, there are two well defined systems of induced resistance which are termed as are induced systemic resistance (ISR) and systemic acquired resistance (SAR). The chemical composition of elicitors as well as controlling pathways for both of these systems are prominently different from each other. SAR is connected with the production of pathogenesis-related (PR) proteins and arbitrated through a salicylic acid dependent procedure (Naz et al. 2018, 2021a). The hypersensitive reaction is known as the initiative response of SAR against pathogenic. However, certain fungal and bacterial species particularly PGPR colonization with plant roots develop systemically the ISR mechanism (Van der Ent et al. 2009; Ullah et al. 2020).

The ISR resistance mechanism is arbitrated by jasmonic acid and ethylene signaling however, the induction of PR-proteins is not included in such type of resistance mechanism (Van der Ent et al. 2009). The biological as well as chemical elicitors which can be released from nonpathogenic or pathogenic microorganisms, can elicit SAR (Ali et al. 2018; Naz et al. 2021b). For instance, the compounds released from Trichoderma spp. can influence SAR as much as they stimulate ISR (Nawrocka and Małolepsza 2013). Chemical stimulators of systemic resistance comprise the synthetic SA-analogues acibenzolar-S-methyl and 2,6-dichloroisoniciotinic acid, methyl jasmonate, chitin and chitosan, β-aminobutyric acid and laminarin, silicon, fatty acids, amino acids, and phosphate salts, remains can also produce systemic resistance, as can ecological agents such as moisture, osmotic, temperature stresses and mechanical wounding (Romero-Puertas et al. 2008).

Primed plants show sooner and sturdier instigation of cellular defense following pathogen challenge relative to the un-primed or untreated plants (Zimmerman et al. 2011; Naz et al. 2021a, 2022), comprising earlier oxidative eruption and strongly up-regulating the expression of defense genes (Zimmerman et al. 2011; Meller Harel et al. 2012; Naz et al. 2014; Butt et al. 2019). While the molecular and physiological mechanisms underlying well-informed responses are widely unidentified, priming has been detected to be an essential part of both ISR and SAR (Yasmin et al. 2020). Molecular indication for the induction of plant defenses systemically via both ISR and SAR paths by biochar was observed (Meller Harel et al. 2012; Jaiswal et al. 2020). Biochar addition to the hitting medium of strawberry plants repressed fungal diseases produced B. cinerea, C. acutatum, and P. apahanis.

The biochar amendments to plant roots confirmed the ethylene and SA-induced expression by increasing the expression of defense-related genes including FaWRKY1, FaPR1, Falox, Faolp2 and Fra a3 (Meller Harel et al. 2012). The question increases, which mechanism(s) are employed by biochar to induce ISR and SAR defense systems, PGPF and PGPR root colonization is known to develop ISR systemically in plants (Hossain et al. 2017). The Bacteroidetes associated Flavobacterium was found to be the most intensely tempted by the biochar. Adherents of the Flavobacterium, usually own a storage of extracellular enzymes for example chitinases and proteinases with having the potential to damage fungi, insects, nematode and bacteria residents (Bernardet and Bowman 2006). Also, many other species of genus Flavobacterium are commonly known to release secondary metabolites including antibiotics (Enisoglu-Atalay et al. 2018).

In addition, some Flavobacterium strains were proficient of instigating a fighting response of plants to diverse diseases (Kolton et al. 2011; Enisoglu-Atalay et al. 2018). Further, hydrolytic enzyme-producing genera including Cellvibrio (Betaproteobacteria) were also persuaded in the rhizosphere of the biochar-altered pepper plants (Kolton et al. 2011). Stimulatingly, biochar alteration was found to antagonize the Pseudoxanthomonas genus (Rajkumar et al. 2008; Kolton et al. 2011). It rests to be grasped what types of biochar can persuade conflict responses, seeing the very big inconsistency in chemical and chemical properties that biochar display, contingent on original pyrolysis and conditions (Sohi et al. 2009). Yet, we imagine that disease control efficiency will differ with other biochar production, biomass sources, temperatures, plant growth systems, plant species and diseases (Table 10.1).

Table 10.1 Impact of biochar amendments on diseases caused by soilborne pathogens

5 Status

Biochar as an important constituent of soil-less substrates has been tried in several experiments; which were focused with numerous types of biochars, and several studies intricate mixtures of biochar with other additions for instance fertilizers and mycorrhiza (Costell et al. 2012) and humic acid harvests (Vickers 2017). The studies verified elevated percentages of biochar: growing media frequently reaching very high biochar percentages (>60%) (Dumroese et al. 2011). Analyses encompassed chemical properties and several parameters of plant development and additional measurements for instance photosynthetic pigments (Fascella 2015). Mostly, biochar had an impartial or helpful influence on plant growth paralleled with peat media when present in absorptions lower than 30%, and in some works even an abundant concentration was found to be not injurious (Méndez et al. 2015; Nieto et al. 2016).

A helpful impact of biochar on reducing plant fungal diseases was first reported about 170 years ago and described consideration in the last decade where numerous pathosystems particularly soilborne pathogens, were considered by different crowds globally (Elad et al. 2011; Postma et al. 2013; Iyyer et al. 2014). Later, Bonanomi et al. 2015 summarized the data from 13 pathosystems that shown the result of biochar on plant diseases. In their study, they described that 85% of the studies exposed a helpful effect of biochar in reducing the severity of plant disease, 12% showed no result, and only 3% presented that biochar mixing up were favorable to plant disease (Zhang and Lin 2014). Though, their analysis did not deliberate the detail that many of these revisions exposed that plant resistance and(or) vulnerability to disease was reliant on the critical aspect of the biochar dosage (Conversa et al. 2015).

6 Conclusion

Biochar can be potentially amended to soil for improving the plant growth, performance and alleviating the negative impacts of soilborne diseases which eventually can reduce the crop yield losses. Biochar amendments cause such changes of controlling pathogens and enhancing the community of beneficial microbes by making adjustments in the soil microflora. Biochar alterations has been reported in this chapter to significantly enhance the beneficial bacterial community which is known to improve the soil and plant health by improving the physico-chemical properties of soil. Moreover, the biochar treatment should be taken as ecofriendly and very efficient practice as it can effectively suppress the pathogenic growth and, applied as a sustainable approach in agriculture systems for soil management.

Therefore, it can be decided by this inclusive review in this chapter that biochar has the potential to increase the soil properties, microbial abundance, plant growth, inhibiting soilborne pathogens and biological nitrogen fixation. Consequently, it is suggested to practice biochar as a soil adjustment for long-term carbon sink renovation.