Regenerative Annual Cropping

Introduction

Regenerative agriculture enhances and sustains the health of the soil by restoring its carbon content. This improves productivity and removes carbon dioxide from the atmosphere.

Project Drawdown defines our Regenerative Annual Cropping solution as any annual cropping system (excluding rice production) that includes at least four of the following six regenerative 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.

Our regenerative annual cropping solution replaces conventional annual cropping as well as conservation agriculture. It incorporates the best of both conservation agriculture and organic/agro-ecological annual cropping. Conservation agriculture becomes more ecological with the addition of elements such as compost application, while organic agriculture is striving to move away from its strong emphasis on tillage. Both may be converging on the approach modeled here.

Scientists estimate that 8 percent of the carbon in the upper layers of Earth’s soils has been released into the atmosphere over the past centuries. Bringing that carbon back home through regenerative agriculture is one of the greatest opportunities to address human and climate health, along with the financial well-being of farmers.

Methodology

Total Land Area

To evaluate the extent to which a Food, Agriculture, and Land Use sector solution can reduce greenhouse gas emissions and sequester carbon, we need to identify the total land area available for that solution in millions of hectares. To avoid double counting, we use an integration model that allocates land area among all Food, Agriculture, and Land Use sector solutions. This involves two steps. First, we classify the global land area into agro-ecological zones (AEZs) based on the land cover, soil quality, and slope and assign AEZs to different thermal moisture regimes. We then classify the AEZs into “degraded” and “nondegraded.” Finally, we allocate the solutions to AEZs, with the solution most suited to a given AEZ or sets of AEZs assigned first, followed by the second-most-suited solution, and so on. Because it’s hard to predict future changes, we assume the total land area remains constant.

Total land available for regenerative annual cropping is 685 million hectares, consisting of minimally sloped nondegraded land used for annual crops . We estimate current adoption (defined as the amount of functional demand supplied in 2014) at 11.84 million hectares. We base this on Research Institute of Organic Agriculture (FIBL) statistics on the total area of organic agriculture (Willer et al. 2018), while acknowledging that not all regenerative agriculture is organic, and not all organic agriculture is regenerative.

Adoption Scenarios

We modeled the adoption rate of regenerative annual cropping on the rapid growth of organic agriculture. The Conservation Agriculture solution is considered a bridge to the Regenerative Annual Cropping solution, and their adoption scenarios are linked. Thus, we assumed that adoption of the Conservation Agriculture solution will increase, then conservation agriculture lands will shift to regenerative annual cropping, a more advanced and desirable form of conservation agriculture. However, we also assumed that the area under conservation agriculture will never drop below the level of adoption in 2014.

We developed nine custom adoption scenarios for regenerative annual cropping. All begin with current adoption of 11.84 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 annual cropping. However, in two of the nine custom adoption scenarios, we modeled adoption of regenerative annual cropping independent of 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 80 percent of the total adoption by 2030. The total land area allocated to the Regenerative Annual Cropping and Conservation Agriculture solutions is the same—685 million hectares—for all adoption scenarios, but allocated differently in each scenario.

We calculated impacts of increased adoption of the Regenerative Annual Cropping solution from 2020 to 2050 by comparing two growth scenarios with a reference scenario in which the market share was fixed at current levels.

• Scenario 1: 219.16 million hectares are adopted (32 percent of the total available land area).
• Scenario 2: 320.45 million hectares are adopted (47 percent of the total available land area).

In the absence of sufficient data about regenerative annual cropping, we used the model developed for the Conservation Agriculture solution, which uses three of the six regenerative agriculture practices (cover cropping, crop rotation, and no-till).

Emissions, Sequestration, and Yield Model

We set sequestration rates using the upper boundary from the Conservation Agriculture solution model because regenerative annual cropping adds known sequestration practices to the three already practiced in conservation agriculture. Sequestration rates are 1.2, 0.6, 1.4, and 0.4 metric 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 59 data points from 40 sources. Emissions reduction rates are identical to those for conservation agriculture: 0.23 metric tons of carbon dioxide equivalent per hectare per year, based on meta-analysis of 14 data points from seven sources. We set a marginal yield loss of 1.02 percent based on meta-analysis of 11 data points from seven sources.

Financial Model

All monetary values are presented in 2014 US$.

Financials are the same as for the Conservation Agriculture solution. We estimated first costs at US$355.05 per hectare; for all agricultural solutions we assume that there is no conventional first cost because agriculture is already in place on the land. We calculated net profit at US$530.39 per hectare per year for the solution (based on meta-analysis of 19 data points from six sources), compared with US$474.21 per year for the conventional practice (based on 36 data points from 19 sources). We calculated the operational cost for conservation agriculture at US$599.03 per hectare per year (based on 17 data points from four sources), compared with US$943.57 per hectare per year for the conventional practice (based on the 30 data points from 12 sources).

Integration

Project Drawdown’s Agro-Ecological Zone model allocates current and projected adoption of solutions to the planet’s forest, grassland, rain-fed cropland, and irrigated cropland. Adoption of the Regenerative Annual Cropping solution was constrained by several factors, including limiting adoption to cropland of minimal slopes and competition with rice solutions. We assigned the Conservation Agriculture and Regenerative Annual Cropping solutions together third-level priority for nondegraded cropland of minimal slopes. Only rice-based solutions are more highly prioritized.

Results

The atmospheric greenhouse gas reduction of Scenario 1 is 15.12 gigatons of carbon dioxide equivalent by 2050 at a net first cost of US$77.10 billion. Lifetime net profit is US$134.4 billion, and lifetime net operational savings are US$2.34 trillion.

The atmospheric greenhouse gas reduction of Scenario 2 was 23.21 gigatons of carbon dioxide equivalent by 2050. Net first cost was US$115.8 billion. Lifetime net profit was US$205.35 billion, and lifetime net operational savings were US$3.52 trillion.

Discussion

Benchmarks

Our mitigation impact is somewhat higher than Intergovernmental Panel on Climate Change (IPCC) benchmarks, which estimate 0.8 gigatons of carbon dioxide equivalent per year by 2030 for cropland management, excluding rice and agroforestry. Griscom et al. (2017) calculate 0.31–0.52 gigatons of carbon dioxide equivalent per year in 2030 for cover cropping, one of the six practices of regenerative annual cropping. Our model shows 0.3–0.5 gigatons of carbon dioxide equivalent per year by 2030 for Conservation Agriculture and 0.5–0.7 for Regenerative Annual Cropping, for a combined 0.86–0.98 gigatons carbon dioxide equivalent per year in 2030.

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, organic agriculture served 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 a fairly large assumption that conservation agriculture will transition to regenerative annual cropping to such a degree, though all it takes for conservation agriculture to meet the criteria is to add any one of the following: green manures, compost application, or organic. Our Conservation Agriculture solution 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.

References

Griscom, Bronson W., Justin Adams, Peter W. Ellis, Richard A. Houghton, Guy Lomax, Daniela A. Miteva, William H. Schlesinger, et al. 2017. “Natural Climate Solutions.” Proceedings of the National Academy of Sciences 114 (44): 11645–50. https://doi.org/10.1073/pnas.1710465114.

Pretty, J. N., A. D. Noble, D. Bossio, J. Dixon, R. E. Hine, F. W. T. Penning de Vries, and J. I. L. Morison. 2006. “Resource-Conserving Agriculture Increases Yields in Developing Countries.” Environmental Science & Technology 40 (4): 1114–19. https://doi.org/10.1021/es051670d.

Willer, Helga, Julia Lernoud, and Laura Kemper. 2018. “The World of Organic Agriculture 2018: Summary,” 10.