**6. Biochar improves nitrogen use efficiency**

Biochar is a recalcitrant source of C, which when applied to the soil slows down the turnover of native SOC, enhances the use efficiency of applied fertilizer-N, and, therefore, reduces fertilizer-induced GHG emissions [1]. Biochar improves N use efficiency through indirect processes including the improvement of soil conditions to maximize nitrogen uptake. This means through the application of biochar, nitrogen in the soil is conserved or the nitrogen that is applied through fertilization (added nitrogen) is conserved. Calys-Tagoe et al. [24] found higher N conserved

**Figure 5.** *Total N content of different treatments. Data replotted from [24].*

in the soil when biochar was applied in combination with nitrogen fertilizer (**Figure 5**). Biochar amendment is said to conserve N in the soil and improve soil biological and physicochemical properties, which increases the ability of the soil to utilize nitrogen and other essential nutrients in the soil.

There are several reasons to expect that biochar might improve nitrogen use efficiency. It is believed that biochar improves nitrogen uptake by plants through the following ways: (1) retaining N in soil through adsorption of ammonia (NH3) and ammonium (NH4 + ), (2) reducing nitrous oxide (N2O) emissions, (3) reducing nitrate (NO3 − ) leaching, and (4) enhancing biological fixation of N in the soil [19]. These functions of biochar in soils have shown to increase nitrogen uptake by plants [37] and improve nitrogen use efficiency [19], either through the action of biochar as fertilizer and/or the improvement of soil condition for enhanced nitrogen uptake. Biochar application resulted in increased N uptake by plants, which was attributed to the ability of biochar to supply more N.

The improved N use efficiency function of biochar is very significant as it can impact the overall carbon balance of agricultural activities. A low ratio of fertilizer nitrogen application to crop nitrogen uptake can, therefore, influence the overall C balance. Higher fertilizer use efficiency may lead to a lower fertilizer requirement per unit yield and usually lower nitrous oxide emission resulting in improved environmental quality.

### **7. Biochar for pests and disease suppression**

Crop pests and diseases constitute important threat to food security and reduce income levels along the value chain of both producers and consumers worldwide. With the increasing global population, the need to maximize food production to feed the world is of utmost importance. To achieve this, there is the need to minimize losses caused by pests and diseases to mitigate the possibility of global food insecurity. Controlling biotic stresses to maximize crop production must, however, be sustainable and environmentally friendly. In view of this, sustainable crop production through integrated pest and disease management (IP&DM) strategies has gained worldwide recognition and the use of organic soil amendments (OSA) such as biochar is an integral tool for the success of this strategy. Apart from managing pest and disease pathogens, OSA have the potential of improving soil tilth, nutrient availability, water-holding capacity, soil microbial diversity, and population dynamics, and reduces nutrient-leaching loss [31].

**101**

*Biochar Application for Improved Resource Use and Environmental Quality*

compounds as mechanisms by which biochar suppresses plant diseases.

The desire to effectively control plant diseases without compromising environmental quality and safety has increased the demand for research into finding sustainable ways of managing pests and diseases. In the context of sustainability, research into the use of organic substances such as animal manure, green manure, organic agro wastes, and compost management have gained tremendous interest among researchers and various stakeholders. OSA do not only have the advantage of improving soil structure and quality but also found to increase the suppressive potential of treated soils thereby inhibiting diseases caused by plant pathogens [32]. OSA have successfully been used to reduce the activities of several plant pathogens such as plant parasitic nematodes, *Fusarium* spp., *Phytophthora* spp., *Pythium* spp., *Rhizoctonia solani*, *Sclerotinia* spp., *Sclerotium* spp., and *Verticillium dahlia* [32]. The use of untreated OSAs have, however, been found to exacerbate activities of disease pathogens and can increase their incidence and severity. Also, the release of certain phytotoxic compounds such as xanthatin and 4-epiisoxanthanol during the decomposition process can damage the roots of plants [32] and make them vulnerable to pathogen attack [33]. The benefits of OSA however, outweigh the constraints and the search for numerous agents for use as OSA is continuous with reports emanating from several research works globally. One such OSA agent that has received global attention and interest is the biochar. This is obtained from the slow pyrolysis of biomass in the absence of air. It is a by-product from the biofuel industry and a high-carbon material [34]. As an OSA, there has been an increased interest in its importance as soil health and disease management agent. Current studies have proven its role in carbon sequestration leading to the removal of desirable carbon from the atmosphere. In addition to this, current studies have pointed to the fact that apart from increasing the cation exchange capacity in organic matter deficient soils, improving the pH status of acidic soils, and increasing nutrition and water holding capacities of soils, it also enriching microorganisms in the soil that improve soil suppression potential against pathogens. Suppressive soils are able to inhibit disease development by stimulating biota activity, increasing and favoring populations of biocontrol agents, and reduce the inoculum potential of both foliar and soilborne pathogens [35]. With regard to soilborne pathogens, biochar has successfully been used to suppress the activities and infection capabilities of pathogens. Data available shows that the application of biochar reduced the infection potential of *Meloidogyne graminicola* in rice [36] and other plant-parasitic nematodes, while it increased the population of free-living nematodes that may be beneficial to the improvement of soil health. Bonanomi et al. [37] reported that the application of biochar was found to be effective in suppressing foliar pathogens such as *Rhizoctonia solani*, *Fusarium*, and *Phytophthora* species. Similarly, the application of biochar was reported to reduce the severity of gray mold disease on both *Lycopersicon esculentum* and *Capsicum annuum* [38]. Also, *Fusarium* root rot disease incidence in asparagus reduced following the application of biochar inoculated with mycorrhizal fungi [39]. Nerome et al. [40] reported that the application of biochar obtained from municipal organic waste inhibited the infection capacity of *Ralstonia solanacearum* to cause disease, increasing the advocacy to use biochar and its amended composts to control fungi and bacterial disease in crop production. The disease suppression potential of biochar is influenced by several mechanisms. According to Rawat et al. [41], the effectiveness of biochar to inhibit disease is linked to the presence of calcium compounds as well as improving the physical, chemical, and biological characteristics of the soil. Similarly, Noble and Coventry [42] hypothesized the induction of systemic resistance in the host plants, enhanced abundance and activities of beneficial microbes, modification of soil quality in terms of nutrient availability, and abiotic conditions; direct fungitoxic effect and sorption of allelopathic and phytotoxic

*DOI: http://dx.doi.org/10.5772/intechopen.92427*

### *Biochar Application for Improved Resource Use and Environmental Quality DOI: http://dx.doi.org/10.5772/intechopen.92427*

*Applications of Biochar for Environmental Safety*

in the soil when biochar was applied in combination with nitrogen fertilizer (**Figure 5**). Biochar amendment is said to conserve N in the soil and improve soil biological and physicochemical properties, which increases the ability of the soil to

There are several reasons to expect that biochar might improve nitrogen use efficiency. It is believed that biochar improves nitrogen uptake by plants through the following ways: (1) retaining N in soil through adsorption of ammonia (NH3)

These functions of biochar in soils have shown to increase nitrogen uptake by plants [37] and improve nitrogen use efficiency [19], either through the action of biochar as fertilizer and/or the improvement of soil condition for enhanced nitrogen uptake. Biochar application resulted in increased N uptake by plants, which was attributed

The improved N use efficiency function of biochar is very significant as it can impact the overall carbon balance of agricultural activities. A low ratio of fertilizer nitrogen application to crop nitrogen uptake can, therefore, influence the overall C balance. Higher fertilizer use efficiency may lead to a lower fertilizer requirement per unit yield and usually lower nitrous oxide emission resulting in improved

Crop pests and diseases constitute important threat to food security and reduce income levels along the value chain of both producers and consumers worldwide. With the increasing global population, the need to maximize food production to feed the world is of utmost importance. To achieve this, there is the need to minimize losses caused by pests and diseases to mitigate the possibility of global food insecurity. Controlling biotic stresses to maximize crop production must, however, be sustainable and environmentally friendly. In view of this, sustainable crop production through integrated pest and disease management (IP&DM) strategies has gained worldwide recognition and the use of organic soil amendments (OSA) such as biochar is an integral tool for the success of this strategy. Apart from managing pest and disease pathogens, OSA have the potential of improving soil tilth, nutrient availability, water-holding capacity, soil microbial diversity, and population dynamics, and reduces nutrient-leaching

), (2) reducing nitrous oxide (N2O) emissions, (3) reducing

) leaching, and (4) enhancing biological fixation of N in the soil [19].

utilize nitrogen and other essential nutrients in the soil.

*Total N content of different treatments. Data replotted from [24].*

+

to the ability of biochar to supply more N.

**7. Biochar for pests and disease suppression**

and ammonium (NH4

−

environmental quality.

nitrate (NO3

**Figure 5.**

**100**

loss [31].

The desire to effectively control plant diseases without compromising environmental quality and safety has increased the demand for research into finding sustainable ways of managing pests and diseases. In the context of sustainability, research into the use of organic substances such as animal manure, green manure, organic agro wastes, and compost management have gained tremendous interest among researchers and various stakeholders. OSA do not only have the advantage of improving soil structure and quality but also found to increase the suppressive potential of treated soils thereby inhibiting diseases caused by plant pathogens [32]. OSA have successfully been used to reduce the activities of several plant pathogens such as plant parasitic nematodes, *Fusarium* spp., *Phytophthora* spp., *Pythium* spp., *Rhizoctonia solani*, *Sclerotinia* spp., *Sclerotium* spp., and *Verticillium dahlia* [32]. The use of untreated OSAs have, however, been found to exacerbate activities of disease pathogens and can increase their incidence and severity. Also, the release of certain phytotoxic compounds such as xanthatin and 4-epiisoxanthanol during the decomposition process can damage the roots of plants [32] and make them vulnerable to pathogen attack [33]. The benefits of OSA however, outweigh the constraints and the search for numerous agents for use as OSA is continuous with reports emanating from several research works globally. One such OSA agent that has received global attention and interest is the biochar. This is obtained from the slow pyrolysis of biomass in the absence of air. It is a by-product from the biofuel industry and a high-carbon material [34]. As an OSA, there has been an increased interest in its importance as soil health and disease management agent. Current studies have proven its role in carbon sequestration leading to the removal of desirable carbon from the atmosphere. In addition to this, current studies have pointed to the fact that apart from increasing the cation exchange capacity in organic matter deficient soils, improving the pH status of acidic soils, and increasing nutrition and water holding capacities of soils, it also enriching microorganisms in the soil that improve soil suppression potential against pathogens. Suppressive soils are able to inhibit disease development by stimulating biota activity, increasing and favoring populations of biocontrol agents, and reduce the inoculum potential of both foliar and soilborne pathogens [35]. With regard to soilborne pathogens, biochar has successfully been used to suppress the activities and infection capabilities of pathogens. Data available shows that the application of biochar reduced the infection potential of *Meloidogyne graminicola* in rice [36] and other plant-parasitic nematodes, while it increased the population of free-living nematodes that may be beneficial to the improvement of soil health. Bonanomi et al. [37] reported that the application of biochar was found to be effective in suppressing foliar pathogens such as *Rhizoctonia solani*, *Fusarium*, and *Phytophthora* species. Similarly, the application of biochar was reported to reduce the severity of gray mold disease on both *Lycopersicon esculentum* and *Capsicum annuum* [38]. Also, *Fusarium* root rot disease incidence in asparagus reduced following the application of biochar inoculated with mycorrhizal fungi [39]. Nerome et al. [40] reported that the application of biochar obtained from municipal organic waste inhibited the infection capacity of *Ralstonia solanacearum* to cause disease, increasing the advocacy to use biochar and its amended composts to control fungi and bacterial disease in crop production. The disease suppression potential of biochar is influenced by several mechanisms. According to Rawat et al. [41], the effectiveness of biochar to inhibit disease is linked to the presence of calcium compounds as well as improving the physical, chemical, and biological characteristics of the soil. Similarly, Noble and Coventry [42] hypothesized the induction of systemic resistance in the host plants, enhanced abundance and activities of beneficial microbes, modification of soil quality in terms of nutrient availability, and abiotic conditions; direct fungitoxic effect and sorption of allelopathic and phytotoxic compounds as mechanisms by which biochar suppresses plant diseases.

Different pesticides are used in crop production to reduce the impact of targeted agent. In addition to its disease suppressive potential, biochar also reduces the impact of pesticides on the environment through the absorption and adsorption of different pesticides [43] to reduce the bioavailability of pesticides due to its large surface area and high porosity. The sorption capacity of biochar amendment is however dependent on age as Martin et al. [44] reported that the herbicide, atrazine adsorption in biochar amended soil decreased with the age of biochar an indication that aging has influence on its usefulness in pesticide sorption. Biochar can again protect roots of plants from phytotoxic compounds in the soil released by roots of other plants, through the decomposition of plant residues and soil amendment as well as agro-waste products and immature compost [45]. The high sorption rate of biochar, on the other hand, can negatively affect the efficacy of agrochemicals and increase the application rates of pesticides.

### **8. Biochar application: a case study in Ghana**

In recent years, agricultural growth in Ghana has seen accelerated growth, but most of this growth is driven by the expansion of the cultivated area rather than by increased yield per unit area. It has been suggested that yield should be increased by at least 20% annually across the staple crops to meet the food needs of the people [46]. This is envisaged to be difficult with the current impact of climate change (evident by the rising temperatures and increased mid-season drought), resource scarcity, and environmental degradation. In sub-Saharan African (SSA), soil fertility decline, mainly through continuous cropping and rapid organic matter mineralization, is the main cause of food insecurity and poverty. Smallholder agricultural production systems in most SSA countries including Ghana are characterized by low productivity due to low and erratic rainfall patterns, outdated agricultural practices, and low application of nutrient inputs. To intensify agriculture, chemical fertilizer is highly utilized.

To pursue the fastest and most practical route to sustainable food production, substantial improvement in crop and soil management practices, which are currently suboptimal, is required. The deployment of soil management technologies such as biochar application is a surest means to reversing the rapid decline in soil fertility in sub-Saharan Africa, particularly Ghana. The large availability of biomass resources in Ghana gives a great potential for biochar production and utilization in the country. This is very important in the tropics since turnover rates of organic matter are much faster. Waste management as a social problem has spared neither the developed nor developing nations as statistics have proven that some developed nations are seriously grappling with this bane. Ghana produces 1.7 billion tons of waste annually (source: ghananewsagency.org).

Biochar research is a recent development in Ghana and so there is a paucity of information regarding its effects on soil properties, crop growth, and yield in Ghanaian soils. The effect of biochar and/or compost applications on the soil pH of the Aiyinase and Cape Coast soils in Ghana after the 14-day incubation period is shown in **Figure 6**. The results revealed a significant increase in the soil pH, following sole and combined applications of compost and biochar in both soils. Also, the application of biochar and compost, alone or in combination, increased soil total organic carbon (TOC) contents in both the Aiyinase and Cape Coast soils (**Figure 6**). The application of biochar significantly improved soil chemical properties with reference to the control.

A case study in Ghana illustrates the significance of biochar application in augmenting water retention in a dryland crop (**Figure 7**). A farmer reports 100%

**103**

(timing and intensity).

**Figure 6.**

**Figure 7.**

**9. Conclusion**

improving tropical soils and crop productivity.

*Biochar Application for Improved Resource Use and Environmental Quality*

*Total organic carbon as affected by different treatments. Data replotted from [24].*

*Total organic carbon as affected by different treatments. Data replotted from [4].*

increase in yields. "Her perception is that the underlying mechanism for the effects she sees is entirely physical, citing two factors: enhanced rainwater infiltration and enhanced soil moisture retention" [10]. Given the fact that drought-susceptible sandy soils are prevalent in Ghana, crop performance is much influenced by rainfall

The results of studies in Ghana indicate the potential exist for farmers to produce their own biochar on-farm, although various factors must be considered in deciding whether this methodology is appropriate in a particular context. Factors such as capacity of farmers determine the pyrolysis conditions and activation methods.

Rainfed agricultural ecosystem in Ghana is extremely fragile, improving soil fertility and crop productivity, and reducing greenhouse gas emission (GHG) is a key factor for developing sustainable agriculture. The review provides insights into the potential of biochar in improving the agroecological system with reference to Ghana. Given the fact that yield gaps are greater in many developing countries, there is considerable need for better soil management technologies to ensure higher yields for improved food security. Biochar application offers a great potential in

*DOI: http://dx.doi.org/10.5772/intechopen.92427*

*Biochar Application for Improved Resource Use and Environmental Quality DOI: http://dx.doi.org/10.5772/intechopen.92427*

**Figure 6.**

*Applications of Biochar for Environmental Safety*

increase the application rates of pesticides.

fertilizer is highly utilized.

**8. Biochar application: a case study in Ghana**

waste annually (source: ghananewsagency.org).

ties with reference to the control.

Different pesticides are used in crop production to reduce the impact of targeted

In recent years, agricultural growth in Ghana has seen accelerated growth, but most of this growth is driven by the expansion of the cultivated area rather than by increased yield per unit area. It has been suggested that yield should be increased by at least 20% annually across the staple crops to meet the food needs of the people [46]. This is envisaged to be difficult with the current impact of climate change (evident by the rising temperatures and increased mid-season drought), resource scarcity, and environmental degradation. In sub-Saharan African (SSA), soil fertility decline, mainly through continuous cropping and rapid organic matter mineralization, is the main cause of food insecurity and poverty. Smallholder agricultural production systems in most SSA countries including Ghana are characterized by low productivity due to low and erratic rainfall patterns, outdated agricultural practices, and low application of nutrient inputs. To intensify agriculture, chemical

To pursue the fastest and most practical route to sustainable food production, substantial improvement in crop and soil management practices, which are currently suboptimal, is required. The deployment of soil management technologies such as biochar application is a surest means to reversing the rapid decline in soil fertility in sub-Saharan Africa, particularly Ghana. The large availability of biomass resources in Ghana gives a great potential for biochar production and utilization in the country. This is very important in the tropics since turnover rates of organic matter are much faster. Waste management as a social problem has spared neither the developed nor developing nations as statistics have proven that some developed nations are seriously grappling with this bane. Ghana produces 1.7 billion tons of

Biochar research is a recent development in Ghana and so there is a paucity of information regarding its effects on soil properties, crop growth, and yield in Ghanaian soils. The effect of biochar and/or compost applications on the soil pH of the Aiyinase and Cape Coast soils in Ghana after the 14-day incubation period is shown in **Figure 6**. The results revealed a significant increase in the soil pH, following sole and combined applications of compost and biochar in both soils. Also, the application of biochar and compost, alone or in combination, increased soil total organic carbon (TOC) contents in both the Aiyinase and Cape Coast soils (**Figure 6**). The application of biochar significantly improved soil chemical proper-

A case study in Ghana illustrates the significance of biochar application in augmenting water retention in a dryland crop (**Figure 7**). A farmer reports 100%

agent. In addition to its disease suppressive potential, biochar also reduces the impact of pesticides on the environment through the absorption and adsorption of different pesticides [43] to reduce the bioavailability of pesticides due to its large surface area and high porosity. The sorption capacity of biochar amendment is however dependent on age as Martin et al. [44] reported that the herbicide, atrazine adsorption in biochar amended soil decreased with the age of biochar an indication that aging has influence on its usefulness in pesticide sorption. Biochar can again protect roots of plants from phytotoxic compounds in the soil released by roots of other plants, through the decomposition of plant residues and soil amendment as well as agro-waste products and immature compost [45]. The high sorption rate of biochar, on the other hand, can negatively affect the efficacy of agrochemicals and

**102**

*Total organic carbon as affected by different treatments. Data replotted from [24].*

**Figure 7.** *Total organic carbon as affected by different treatments. Data replotted from [4].*

increase in yields. "Her perception is that the underlying mechanism for the effects she sees is entirely physical, citing two factors: enhanced rainwater infiltration and enhanced soil moisture retention" [10]. Given the fact that drought-susceptible sandy soils are prevalent in Ghana, crop performance is much influenced by rainfall (timing and intensity).

The results of studies in Ghana indicate the potential exist for farmers to produce their own biochar on-farm, although various factors must be considered in deciding whether this methodology is appropriate in a particular context. Factors such as capacity of farmers determine the pyrolysis conditions and activation methods.

### **9. Conclusion**

Rainfed agricultural ecosystem in Ghana is extremely fragile, improving soil fertility and crop productivity, and reducing greenhouse gas emission (GHG) is a key factor for developing sustainable agriculture. The review provides insights into the potential of biochar in improving the agroecological system with reference to Ghana. Given the fact that yield gaps are greater in many developing countries, there is considerable need for better soil management technologies to ensure higher yields for improved food security. Biochar application offers a great potential in improving tropical soils and crop productivity.
