**3.3 The extent of biochar use in agriculture**

The continued awareness of the benefits of biochar as a carbon sequester and soil conditioner has propelled its demand and use in the agricultural sector worldwide [34]. Research institutions and organizations have championed evidence-based research as incentives to upscale biochar acceptability and salability to farmers. One such organization is the International Biochar Initiative (IBI), which is a non-profit organization founded in 2006. Even though it is the biggest biochar promoter, several other establishments exist in different countries and regions of the world [25, 35, 36]. These biochar promoter organizations have been at the forefront in organizing scientific conferences to share insights on the latest research on biochar. Most importantly, they have been instrumental in proposing policies regarding biochar legislation. One such milestone is the Post-Kyoto Climate Agreements under the UN Framework Convention on Climate Change (UNFCCC), where biochar was unilaterally accepted a viable mitigation strategy [30, 32]. The Kyoto protocol was further intended to aid small economy countries to achieve sustainable development goals and to secure compliance with GHG emission minimization targets [37].

### **Crop Burundi (×1000MT) Kenya (×1000MT) Rwanda (×1000MT) S. Sudan (×1000MT) Tanzania (×1000MT) Uganda (×1000MT)** Beans, dry 3.83 13.12 6.42 0.011 14.41 9.96 Maize 2.55 32.59 3.93 1.06 61.57 27.47 Millet 0.12 0.69 0.069 0.059 3.83 2.50 Potatoes 0.60 5.62 2.85 — 6.27 1.00 Rice, paddy 1.59 1.20 1.45 — 44.59 3.89 Sorghum 0.37 3.02 2.53 9.27 13.60 6.51 Soybeans 0.072 0.044 0.84 — 0.116 0.80 Wheat 0.12 2.27 0.17 — 1.59 0.34 Barley — 0.93 — — 0.18 — Oats — 0.059 — — — — **Total 9.26 59.54 18.26 10.40 146.15 52.48**

**129**

conditions [36].

**Figure 2.**

**productivity**

*Biochar Potential in Improving Agricultural Production in East Africa*

Greenkeeper realized that addition of traces of charcoal enhanced soil porosity [3]. Different kinds of biochar porosity exist depending on pore size. Pores can be categorized into micropores (diameter < 2 nm), mesopores (diameter 2–50 nm), and macropores (diameter > 200 nm) [3]. Mostly, macropores are susceptible to water, plant roots, and fungal hyphae penetration. Thus, the large pores influence the soil's hydrology and microbial ecosystem. It is easy to see the biochar pore size distributions using the scanning electron micrographs depending on the parent plant structure, see **Figure 2**. Therefore, it is the high porosity property of biochar that makes it contributes to the susceptibility of soil to water infiltration and increased micropore network in the soil [1, 30]. Thus, water retention in both sandy and silty soils can be significantly improved with the incorporation of biochar [1, 30].

*Scanning electron micrographs of biochar particles showing porosity. Source: Brewer [3].*

Biochar's larger surface area to volume ratio also plays a significant role in cation exchange capacity (CEC) and the extent to which biochar can be integrated into the soil. The bigger the biochars' surface area, the greater the chemical exchanges; it can accommodate per unit gram [38]. Thus, it potentially curbs any form of nutrient leaching while boosting nutrients uptake [7, 31]. Biochar's bulk density is relatively low compared to soil bulk density; this encourages ease of nutrient release to plants

Biochar is alkaline; this may influence the type of soil upon which it can be applied [39]. Depending on the type of feedstock pyrolyzed, biochar contains both primary and trace mineral elements useful for plants development [4]. Nonetheless, it has been noted that the presence of various functional hydrocarbon groups in biochar limits its release of water to plant roots especially in water stress

East Africa is among the countries with the highest nutrient loss across sub-Saharan Africa with annual nutrient depletion rate of 41 kg N, 4 kg P and 31 kg K per hectare [40]. Even though soil fertility is quite dynamic, its inherent chemical, biological, physical, and anthropogenic characteristics play a significant role too [40]. Most soils in East Africa are acidic without enough nutrients to support sustainable crop production. This is because a bigger portion of the soils are extremely weathered, making them nutrient-deficient, especially with a limited stock of phosphorus, potassium, calcium, magnesium, and sulfur [41]. Similarly, soil acidity

**4. Potential of biochar use to boost East African agricultural** 

and also lowering the effects of soil compatibility [3, 4].

*DOI: http://dx.doi.org/10.5772/intechopen.92195*

**3.4 How does biochar improve soil properties?**

The historical background about the use of biochar as soil amendment tool can be traced back to as earlier as 1929 when John Morley working with the US National

### **Table 3.**

*Source: FAOSTAT [33].*

*Comparison of crop residues among East African countries (×1000MT) nitrogen content.*

*Biochar Potential in Improving Agricultural Production in East Africa DOI: http://dx.doi.org/10.5772/intechopen.92195*

*Applications of Biochar for Environmental Safety*

**3.3 The extent of biochar use in agriculture**

**3.4 How does biochar improve soil properties?**

**Kenya (×1000MT)**

the major food crops [33].

**Crop Burundi** 

Beans, dry

Rice, paddy

*Source: FAOSTAT [33].*

**(×1000MT)**

from the atmosphere, the predisposition asserted by industrial activities makes the process even longer. This means that even though biochar has the potential to sequester carbon, sustainable land use change and pollution control are indispensable. With improved and cheaper innovations like pyrolysis techniques, biochar productions potentially depend on biomass availability [3, 17, 27]. **Table 3** highlights the average agricultural wastes across East African countries generated from

The continued awareness of the benefits of biochar as a carbon sequester and soil conditioner has propelled its demand and use in the agricultural sector worldwide [34]. Research institutions and organizations have championed evidence-based research as incentives to upscale biochar acceptability and salability to farmers. One such organization is the International Biochar Initiative (IBI), which is a non-profit organization founded in 2006. Even though it is the biggest biochar promoter, several other establishments exist in different countries and regions of the world [25, 35, 36]. These biochar promoter organizations have been at the forefront in organizing scientific conferences to share insights on the latest research on biochar. Most importantly, they have been instrumental in proposing policies regarding biochar legislation. One such milestone is the Post-Kyoto Climate Agreements under the UN Framework Convention on Climate Change (UNFCCC), where biochar was unilaterally accepted a viable mitigation strategy [30, 32]. The Kyoto protocol was further intended to aid small economy countries to achieve sustainable development goals and to secure compliance with GHG emission minimization targets [37].

The historical background about the use of biochar as soil amendment tool can be traced back to as earlier as 1929 when John Morley working with the US National

> **Rwanda (×1000MT)**

Maize 2.55 32.59 3.93 1.06 61.57 27.47 Millet 0.12 0.69 0.069 0.059 3.83 2.50 Potatoes 0.60 5.62 2.85 — 6.27 1.00

Sorghum 0.37 3.02 2.53 9.27 13.60 6.51 Soybeans 0.072 0.044 0.84 — 0.116 0.80 Wheat 0.12 2.27 0.17 — 1.59 0.34 Barley — 0.93 — — 0.18 — Oats — 0.059 — — — — **Total 9.26 59.54 18.26 10.40 146.15 52.48**

*Comparison of crop residues among East African countries (×1000MT) nitrogen content.*

3.83 13.12 6.42 0.011 14.41 9.96

1.59 1.20 1.45 — 44.59 3.89

**S. Sudan (×1000MT)**

**Tanzania (×1000MT)**

**Uganda (×1000MT)**

**128**

**Table 3.**

**Figure 2.** *Scanning electron micrographs of biochar particles showing porosity. Source: Brewer [3].*

Greenkeeper realized that addition of traces of charcoal enhanced soil porosity [3]. Different kinds of biochar porosity exist depending on pore size. Pores can be categorized into micropores (diameter < 2 nm), mesopores (diameter 2–50 nm), and macropores (diameter > 200 nm) [3]. Mostly, macropores are susceptible to water, plant roots, and fungal hyphae penetration. Thus, the large pores influence the soil's hydrology and microbial ecosystem. It is easy to see the biochar pore size distributions using the scanning electron micrographs depending on the parent plant structure, see **Figure 2**. Therefore, it is the high porosity property of biochar that makes it contributes to the susceptibility of soil to water infiltration and increased micropore network in the soil [1, 30]. Thus, water retention in both sandy and silty soils can be significantly improved with the incorporation of biochar [1, 30].

Biochar's larger surface area to volume ratio also plays a significant role in cation exchange capacity (CEC) and the extent to which biochar can be integrated into the soil. The bigger the biochars' surface area, the greater the chemical exchanges; it can accommodate per unit gram [38]. Thus, it potentially curbs any form of nutrient leaching while boosting nutrients uptake [7, 31]. Biochar's bulk density is relatively low compared to soil bulk density; this encourages ease of nutrient release to plants and also lowering the effects of soil compatibility [3, 4].

Biochar is alkaline; this may influence the type of soil upon which it can be applied [39]. Depending on the type of feedstock pyrolyzed, biochar contains both primary and trace mineral elements useful for plants development [4]. Nonetheless, it has been noted that the presence of various functional hydrocarbon groups in biochar limits its release of water to plant roots especially in water stress conditions [36].
