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Biochar & Climate-Smart Agriculture (CSA)

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Climate-smart agriculture (CSA) is a holistic approach to managing landscapes, cropland, livestock, forests, and fisheries that addresses the interconnected challenges of food security and climate change.

CSA aims to simultaneously achieve three outcomes:

  1. Increased productivity: Produce more and better food to improve nutrition security and boost incomes, especially of 75 percent of the world’s poor who live in rural areas and mainly rely on agriculture for their livelihoods.
  2. Enhanced resilience: Reduce vulnerability to drought, pests & diseases and other climate-related risks and shocks and improve capacity to adapt and grow in the face of longer-term stresses like shortened seasons and erratic weather patterns.
  3. Reduced emissions: Pursue lower emissions for each calorie or kilo of food produced, avoid deforestation from agriculture and identify ways to absorb carbon out of the atmosphere.

While built on existing knowledge, technologies, and principles of sustainable agriculture, CSA is distinct in several ways. First, it has an explicit focus on addressing climate change. Second, CSA systematically considers the synergies and tradeoffs that exist between productivity, adaptation and mitigation. Finally, CSA aims to capture new funding opportunities to close the deficit in investment.

Climate change is reducing crop yields, the nutritional quality of major cereals, and livestock productivity on farms. Significant adaptation investments will be required to maintain current yields and increase production and food quality to meet demand.

The problem can also be reversed. Agriculture contributes significantly to the climate problem. It currently accounts for 19-29% of total greenhouse gas emissions (GHG). If nothing is done, that percentage could rise significantly as other sectors reduce their emissions. Furthermore, one-third of all food produced globally is lost or wasted. Addressing food loss and waste is critical to meeting climate goals and reducing environmental stress.

Biochar Enhances the Capacity of Climate-Smart Agriculture to Mitigate Climate Change

Biochar and Climate-Smart Agriculture

As indicated already, one of the major non-climate-related stresses that smallholder or subsistence farmers face is poor soil quality, which exacerbates the direct negative impact of climate change on crop and livestock productivity.

Because the majority of smallholder and subsistence farmers live in marginal areas with poor soil quality, various climate-smart technologies such as conservation and conventional agriculture (CA), organic agriculture, and ecological agriculture, among others, have been researched with the potential to improve the quality of their soils, thus increasing the resilience of these resource-poor farmers.

The use of biochar, which is useful in sequestering Soil Organic Carbon (SOC) in soils, is one technology that dates back centuries but has recently gained traction as a winner in improving the quality of poor soils.

In soil carbon usually referred to as Soil Organic Carbon (SOC) plays a critical role in soil quality as it is responsible for, releasing polysaccharides that encourage soil particle aggregation, increases soil water-holding capacity, improves the nutrient retention capacity of soils, releases micronutrients in soil, improves soil biological activity which is critical in the mineralization processes.

Although the Green Revolution increased food security in most parts of the world, this was not the case in most Sub-Saharan African countries because most smallholder farmers could not afford the high cost of inputs for the proposed new agricultural system. Furthermore, even those who implemented some aspects of the Green Revolution did not achieve sustainable yield gains because these rely on optimized levels of SOC, which is typically low in the soils of smallholder farmers.

As a result, biochar provides a long-term sustainable soil fertility management system for these smallholder farmers. Biochar, unlike existing soil management options such as conservation and conventional agriculture, organic agriculture, and ecological agriculture, promises to create a complementary climate-smart effect.

Most smallholder farmers recognize the importance of adding SOC to their poor-quality soils, and some have used organic materials such as animal manure and plant biomass to increase the SOC content of their soils. However, due to the rapid biodegradation of these organic sources in the soil, where microorganisms use the carbon as a source of energy, converting the added carbon into carbon dioxide, there is a minimal cumulative increase in SOC in their soils over time, necessitating the need for repeat carbon inputs to soils.

This is where biochar contributes to a more sustainable climate-smart method of managing SOC stocks in soils through enhanced carbon sequestration while preventing SOC loss to the atmosphere as carbon dioxide.

(A Schematic diagram showing the properties of biochar and the possible climate smart effects it can have when used in agriculture)

Mitigation and Adaptation Potential of Biochar in a Changing Climate

The use of biochar in agriculture is gaining popularity due to the potential environmental benefits and positive contribution to climate-smart agriculture. Biochar-induced improvements to soil health are mainly due to, its longevity in the soil and ability to improve soil structure and hold available nutrients.

Biochar increases soil organic matter content, which is important because it improves water retention, microbial activity, nutrient cycling, and crop productivity.

In general, scientists agree that amending soil with biochar can improve soil structure, which improves hydraulic properties. According to some research findings, biochar’s ability to increase soil infiltration rate and water-holding capacity can potentially result in yield improvements, particularly in dry conditions.

Because biochar has a low density in comparison to mineral particles, it reduces soil bulk density. Furthermore, the high macro porosity of biochar increases soil porosity either directly through pores in the biochar particles or indirectly through the formation of new macro pores and the rearrangement of soil particles. The macro pores and high internal surface area provide a suitable living environment for soil microorganisms while also retaining soluble inorganic nutrients.

Smallholder farmers’ conventional tillage practices increase the release of GHGs, particularly CO2, into the atmosphere by increasing the rate of organic matter decomposition, thereby accelerating global warming and soil degradation. In contrast, amending soils with biochar reduces global warming by removing CO2 from the atmosphere and permanently storing it in the soil.

The exact mechanisms that contribute to the effects of biochar amendment on soil CO2 emission are still ambiguous; however, researchers attribute it to the fact that biochar is resistant to decomposition and changes soil temperature, moisture, and microbial activity.

Biochar’s effect on methane (CH4) and nitrous oxide (N2O) is still unknown, particularly in Africa. Biochar has been shown to reduce denitrifying microorganisms by altering the soil’s nature, which includes decreasing bulk density, increasing pH, and increasing soil moisture content, and thus lowering N2O emissions. Furthermore, biochar absorbs ammonia and slowly releases it for plant uptake, reducing volatilization and loss into the atmosphere.

The CHAR project, led by the University of Liege, looks into soil management practices that reduce GHG emissions and for the improvement of crop performance while reducing fertilizer inputs. This project investigates the effects of charcoal accumulation in the soil (a carbon-rich solid phase produced by pyrolysis) on carbon storage, nutrient and water cycles, and agronomic performance.

In Wallonia during the 18th century, the production of charcoal was greatly expanded in order to provide energy for the pre-industrial steel industry. During this time, 75% of Wallonia’s deforested land was dedicated to the production of charcoal, resulting in numerous black patches (called aires de faulde) that can still be seen today in agricultural fields. This biochar enrichment causes changes in the biogeochemical and hydrodynamic properties of Walloon soils.

Likewise many studies have shown that biochar increases fertility and water holding capacity in soil in addition to increase carbon stocks.

Finally, biochar which emerge as a nature-based solution could play a role in sustainable intensification and climate-smart agriculture, through its potential in strengthening the resilience of smallholder farmers’ agricultural systems and could help in climate mitigation and address sustainable development goals.

References:-

Biochar picture source: https://www.wur.nl/en/ Research-Results/Research-Institutes/Environmental-Research/Facilities-Products/EnvironmentalSciences-Laboratories/Soil-Hydro-Physics-Laboratory/Research/Biochar.htm. Accessed 17 July 2020; Soil picture source: https://www.agrocares.com/en/news/10-questions-about-soils/. Accessed 17 July 2020

Nyambo, P., Mupambwa, H. A., & Nciizah, A. D. (2020). Biochar enhances the capacity of climate-smart agriculture to mitigate climate change. Handbook of Climate Change Management: Research, Leadership, Transformation, 1-18.

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