Regenerative Agriculture
Project Drawdown defines regenerative agriculture as any annual cropping system that includes at least four of the following six practices: compost application, cover crops, crop rotation, green manures, no-till or reduced tillage, and/or organic production. These practices sequester carbon in soils and reduce emissions at modest rates, but have wide adoption potential and thus impressive mitigation potential. This practice replaces conventional annual cropping as well as conservation agriculture.
These diverse systems incorporate the best of both conservation agriculture and organic/agroecological annual cropping. Conservation agriculture becomes more ecological by adding additional elements like compost application, while organic is striving to move away from its strong emphasis on tillage. Both may be converging on a new approach, which is modeled here.
Note: Many other Drawdown practices are also defined as “regenerative” by many authors, but this solution focuses on annual cropping only, excluding rice production.
Methodology
Total Land Area [1]
Total land available for regenerative agriculture is 788 million hectares, consisting of annual cropland of minimal slopes. [2] Current adoption [3] is estimated at 43.6 million hectares, based on the total area of organic agriculture (Willer, 2016) – though not all regenerative agriculture is organic, and not all organic is regenerative.
Adoption Scenarios [4]
The adoption rate of regenerative agriculture is modeled on the rapid growth of organic agriculture (Willer, 2016). Conservation agriculture is considered a bridge to regenerative agriculture, and their adoption scenarios are linked. Thus, it was assumed that the adoption of conservation agriculture will increase initially from its current growth rate and level of adoption, and later on those adopted areas will be shifted to regenerative agriculture, a more advanced and desirable form of conservation agriculture. However, it was also assumed that the area under conservation agriculture will never be zero, and it will remain at the minimum of the level of the current adoption as of the base year (2014).
Seven custom adoption scenarios were developed for regenerative agriculture. All begin with current adoption of 43.6 million hectares. Adoption is based on regional organic agriculture growth rates, with additional growth to reflect conversion of land area from conservation agriculture to regenerative agriculture. However, in two of the seven custom adoption scenarios, adoption of regenerative agriculture was modeled independent of the conservation agriculture land area conversion. The conservative adoption scenarios assume that adoption continues through 2050, while the aggressive adoption scenarios assume an early high growth, resulting in peak adoption by 2030. The total land area allocated to regenerative agriculture and conservation agriculture is the same – 788 million hectares – which is allocated differently under different custom adoption scenarios.
Impacts of increased adoption of regenerative agriculture from 2020-2050 were generated based on three growth scenarios, which were assessed in comparison to a Reference Scenario where the solution’s market share was fixed at the current levels.
- Plausible Scenario: Analysis of the seven custom adoption scenarios results in the adoption of 407.0 million hectares under regenerative agriculture by 2050.
- Drawdown Scenario: This scenario results in the adoption of 485.9 million hectares under regenerative agriculture by 2050.
- Optimum Scenario: This scenario results in the adoption of 555.0 million hectares under regenerative agriculture by 2050.
In the absence of sufficient data about regenerative agriculture, this study uses the Drawdown model developed for conservation agriculture, which uses three of the six regenerative agriculture practices (cover cropping, crop rotation, and no-till).
Emissions, Sequestration, and Yield Model
Sequestration rates are set using the upper boundary from the conservation agriculture model, as regenerative agriculture adds known sequestration practices to the three already practiced in conservation agriculture. Sequestration rates are 1.2, 0.6, 1.4, and 0.4 tons of carbon per hectare per year for tropical-humid, temperate/boreal-humid, tropical semi-arid, and temperate/boreal semi-arid areas, respectively. These rates are the result of meta-analysis of 62 data points from 34 sources. Emissions reduction rates are identical to conservation agriculture: 0.23 tons of carbon dioxide-equivalent per hectare per year, based on meta-analysis of 16 data points from 7 sources.
Yield gains compared to business-as-usual annual cropping were identical to conservation agriculture, and set at 8.3 percent based on meta-analysis of 7 data points from 3 sources.
Financial Model
In the case of financials, the figures are exactly the same as in the conservation agriculture model. First costs are estimated at US$157.32 per hectare; [5] for all agricultural solutions it is assumed that there is no conventional first cost, as agriculture is already in place on the land. Net profit per hectare is US$650.65 per year, compared to US$376.98 per year for the conventional practice.
Integration [6]
Drawdown’s Agro-Ecological Zone model allocates current and projected adoption of solutions to the planet’s forest, grassland, rainfed cropland, and irrigated cropland areas. Adoption of regenerative agriculture was constrained by several factors. These include limiting adoption to cropland of minimal slopes and competition for said cropland with rice solutions. The combined conservation/regenerative agriculture practice is assigned third-level priority for non-degraded cropland of minimal slopes. Only rice-based solutions are more highly prioritized.
Results
Total adoption in the Plausible Scenario is 407.0 million hectares in 2050, representing 51.6 percent of the total suitable land. Of this, 357.4 million hectares are adopted from 2020-2050. The emissions impact of this scenario is 23.1 gigatons carbon dioxide-equivalent reduced by 2050. Net cost is US$57.2 billion. Net savings is US$1,928.1 billion. Increased crop yield between 2015-2050 is 2,293.9 million metric tons.
Total adoption in the Drawdown Scenario is 485.9 million hectares in 2050, representing 61.6 percent of the total suitable land. Of this, 442.3 million hectares are adopted from 2020-2050. The impact of this scenario is 32.2 gigatons carbon dioxide-equivalent by 2050.
Total adoption in the Optimum Scenario is 555.0 million hectares in 2050, representing 70.4 percent of the total suitable land. Of this, 511.4 million hectares are adopted from 2020-2050. The impact of this scenario is 32.1 gigatons carbon dioxide-equivalent by 2050.
Discussion
Benchmarks
Mitigation impact is somewhat higher than Intergovernmental Panel on Climate Change (IPCC) benchmarks, which estimate 0.8 gigatons carbon dioxide-equivalent per year by 2030 for cropland management, excluding rice and agroforestry (Smith, 2007). The Drawdown model shows 0.4-0.7 gigatons carbon dioxide-equivalent per year by 2030 for conservation agriculture and 0.5-0.7 for regenerative agriculture, for a combined 0.9-1.4 gigatons carbon dioxide-equivalent per year in 2030. This is slightly higher than the benchmark, reflecting the higher sequestration rate modeled for regenerative agriculture.
Limitations
Basing current adoption on organic agriculture is problematic in several ways. Not all organic agriculture is regenerative, nor is all regenerative agriculture organic. Most land that is certified organic is grassland, rather than annual cropland. However, it serves as a stand-in given the lack of better data. The area is likely at least this large: for example, Pretty et al (2006) estimate 37 million hectares of agroecological production in the tropics alone. It is also a fairly large assumption that conservation agriculture will transition to regenerative agriculture to such a degree, though all it takes for conservation agriculture to meet the criteria is the addition of any one of the following: green manures, compost application, or organic. The Drawdown conservation agriculture model, on which much of this study was based, was itself constrained by limited access to financial data at the farm, regional, and global levels. Future work should include collecting additional data on first costs and net profit per hectare.
Conclusions
An international movement addressing soil health and carbon sequestration in annual cropping systems is growing. This is extremely timely given agriculture's current emissions and the great potential for sequestration on croplands.
[1] To learn more about the Total Land Area for the Food Sector, click the Sector Summary: Food link below.
[2] Determining the total available land for a solution is a two-part process. The technical potential is based on the suitability of climate, soils, and slopes, and on degraded or non-degraded status. In the second stage, land is allocated using the Drawdown Agro-Ecological Zone model, based on priorities for each class of land. The total land allocated for each solution is capped at the solution’s maximum adoption in the Optimum Scenario. Thus, in most cases the total available land is less than the technical potential.
[3] Current adoption is defined as the amount of functional demand supplied by the solution in the base year of study. This study uses 2014 as the base year due to the availability of global adoption data for all Project Drawdown solutions evaluated.
[4] To learn more about Project Drawdown’s three growth scenarios, click the Scenarios link below. For information on Land Use Sector-specific scenarios, click the Sector Summary: Food link.
[5] All monetary values are presented in US2014$.
[6] For more on Project Drawdown’s Food Sector integration model, click the Sector Summary: Food link below.
