A regenerative biomass model can tackle climate change by producing high value added products in degraded soils.  About 3000 billion metric tons of carbon are in the soil. That is 315 times the amount of carbon we release into the atmosphere currently.  Can regenerative biomass crops profitably increase soil carbon?

If you want to do something about global warming, look under your feet.The land under our feet and the plant matter it contains is  could offset a significant amount of carbon emissions if managed properly. Managed well, soil’s ability to trap carbon dioxide is potentially much greater than previously estimated, according to Stanford researchers who claim the resource could “significantly” offset increasing global emissions. They call for a reversal of federal cutbacks to related research programs to learn more about this valuable resource. A 2017 study estimated that with better management, global croplands have the potential to store an additional 1.85 gigatons carbon each year—as much as the global transportation sector emits annually.

Climate, soils, biophysical and socioeconomic systems are interconnected in complex ways. Contemporary discussions had been heavily focused on curbing emissions of fossil fuels. But a look at soil brings a sharper focus on potential carbon sinks. Reducing emissions is crucial, but soil carbon sequestration needs to be part of the picture. The relationship between climate change and soil carbon resources is of key concern to human society. Current soil management practices may not be robust enough to cope with the impacts of climate change. In many locations, soil management cannot satisfactorily cope even with current climate variability. Currently, soils remove about 25 percent of the world’s fossil fuel emissions each year. Most soil carbon is stored as permafrost and peat in Arctic areas, and in moist regions like the boreal ecosystems of Northern Eurasia and North America. Soils in hot or dry areas store less carbon, but a perennial cover, trees and grasses in areas with bare soil, acid leached soils in tropics such as subsaharian Africa, South East Asia, India, Central and South America and The Caribbean, or even some abandoned lands in temperate climates such as EU, China and North America can follow this approach by replicating a model we explain here.

Management practices effective in increasing SOC stocks include: (Source: FAO)

Before entering into details of our solutions, just take a look to those practices promoted by FAO in order to sequester CO2 and increase soil organic matter in the soil:

1. Improved plant productivity through nutrient management, rotations and improved farming practices;

2. Reduced or conservation tillage and residue management;

3. More effective use of organic amendments;

4.  Land use change, for example from crops to perennial grass or trees;

5. Set-aside;

6. Agroforestry;

7. Optimizing livestock densities;

8 Planting legumes or improving the crop mix.

 

Now, why biomass and perennial bioenergy crops can contribute to massive escalation of these practices?

Biomass crops can produce high value added products from relatively simple products farmers can grow without excessive amounts of chemicals and deliver straw, woody chips and other raw materials. In this regard there is massive evidence that perennial species can improve degraded lands and contribute to a decarbonized economy. In recent years, technology evolved in a way that it is already very cost effective to use thermal energy (hear/steam or other sources of bioenergy) to transform these products not just into dried or processed food or feeds for animals, but also into bio-fertilizers, industrial fibers, biochar, liquid, gaseous or solid biofuels and with particular interest many solid bio-products that can replace fossil sources industries such as plastics while sequestering CO2 in the process. In other words, a factory and a forest or perennial agroforestry system with biodiversity that contributes to carbon sequestration and produces high value added products and its own renewable energy source.

Of course this all can be applied to regenerate mining areas in reclamation lands or contribute to face land desertification and improve soil organic matter in the soil as we show here. Learn more about this here.

copiaçu pasto

Each hectare planted with this grass can yearly capture more than 100 tons of CO2 and sequester carbon into the soil by the beneficial biologically activated and recalcitrant biochar applied, that helps to increase nutrient holding capacity and store carbon below ground.

The solution presented here includes a combination of perennial “non-invasive” hybrids with extraordinary productivity such as several bioenergy crops, together with composting alternatives and soil amendment techniques including biochar produced from residues collected at regional or farm levels such as olive pruning, cocoa and rice husks or many others, and the logistic chains to be synergetic with processing facilities. The systems suggested have sound evidence of being positive for biodiversity when planted in marginal lands with current levels of degradation. Note that 50% of our lands are degraded and more than 2.9 billion hectares are available and not expected to be used for food production.

 

Regenerating soil carbon by promoting biorefineries

A biorefinery is a decentralized operation with its own clan energy being produced through biomass (or some other renewable energy sources if more competitive). The factory produces high value added products including processed food and beverages, construction materials as cement or bricks, bio-plastics, liquid or gaseous biofuels, bio-fertilizers, biochar and many more examples.

bioeconomy and products

Residues from bio-refineries may include ashes (rich in potassium and phosphorous among other minerals), liquid and solid fractions from biogas digestates and food processing waste materials.  We have explained this with more details in a separate post.

Composting biochar and these raw materials together with legumes and other nitrogen sources facilitates the implementation of these solutions (See below).

Image result for biomass biorefinery rural development logistics

Mussato and Dragone (2016).

Image result for bamboo crops

Bamboo cropping systems are another example of carbon sequestration alternatives as they produce excellent income while producing several products including fibers, biomaterials, biochar and clean energy

 

Soil carbon and nitrogen

Many aspects of carbon sequestration will require a complete regeneration of soils and nitrogen may be a big issue during the process. Methods promoted by our group include nitrogen fixation by legumes, intercropping, cover crops and several recently released planting materials that include herbaceous and woody legume species.

Agroforestry in tropical areas allow grazing and woody crops to avoid deforestation and produce energy and food from same lands. Photo: Leucaena trees and guinea grass in tropical lands. Photo: tropicalforages.info

Agroforestry in tropical areas allow grazing and woody crops to avoid deforestation and produce energy and food from same lands. Photo: Leucaena trees and guinea grass in tropical lands. Photo: tropicalforages.info

While these solutions may increase nitrogen during initial stages, the composting and soil amendment implementation combined with microbes and fungi will make the difference. A few years after soil regeneration begins, most grasses, bamboo and several trees can produce in a year between 10 to 70 dry tons per hectare. The perennial habit, the regular inoculation in biochar and compost and the combination with intercropped legumes help to sustain productivity for long periods until pastures and woody plantations are replaced. As only aboveground biomass is harvested, soil organic matter tends to increase in the soil.

A combination with livestock waste materials is also being implemented and considered in many bioenergy projects. 

 

 

sunn hemp cover crop

References
– FAO (2015) Can Carbon offset climate change?

- Farmland could be used to sustainably offset America’s entire carbon footprint—if the will exists

Soil carbon sink? It depends also on nitrogen

Soil as Carbon Storehouse: New Weapon in Climate Fight?

Tree planting ‘has mind-blowing potential’ to tackle climate crisis

Mussato and Dragone (2016) Biomass Pretreatment, Biorefineries, and Potential Products for a Bioeconomy Development