Regenerative Annual Cropping
Project Drawdown defines regenerative annual cropping 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 Project Drawdown practices are also defined as “regenerative” by many authors, but this solution focuses on annual cropping only, excluding rice production.
Total Land Area
Total land available for regenerative annual cropping is 685 million hectares, consisting of annual nondegraded cropland of minimal slopes. Current adoption is estimated at 11.84 million hectares, based on the total area of organic agriculture by Research Institute of Organic Agriculture (FIBL) statistics (Willer et al. 2018)– though not all regenerative agriculture is organic, and not all organic agriculture is regenerative.
The adoption rate of regenerative annual cropping is modeled on the rapid growth of organic agriculture (Willer, 2016). Conservation agriculture is considered a bridge to regenerative annual cropping, 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 annual cropping, 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).
Nine custom adoption scenarios were developed 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, adoption of regenerative annual cropping 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 (80% of the total adoption) by 2030. The total land area allocated to regenerative annual cropping and conservation agriculture is the same—685 million hectares—which is allocated differently under different custom adoption scenarios.
Impacts of increased adoption of regenerative annual cropping from 2020 to 2050 were generated based on two growth scenarios. These were assessed in comparison with a Reference Scenario, in which the solution’s market share was fixed at the current levels.
- Scenario 1: Analysis of the seven custom adoption scenarios results in the adoption of 221.3 million hectares under regenerative annual cropping by 2050.
- Scenario 2: This scenario results in the adoption of 321.9 million hectares under regenerative agriculture by 2050.
In the absence of sufficient data about regenerative annual cropping, 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 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 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 conservation agriculture: 0.23 tons of carbon dioxide-equivalent per hectare per year, based on meta-analysis of 14 data points from seven sources.
Marginal yield loss of 1.02 percent is set under regenerative annual cropping based on meta-analysis of 11data points from seven sources.
In the case of financials, the figures are exactly the same as in the conservation agriculture model. First costs are estimated at US$355.05 per hectare; for all agricultural solutions it is assumed that there is no conventional first cost because agriculture is already in place on the land. Net profit is calculated 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). While the operational cost is calculated at US$599.03 per hectare per year for the solution (based on 17 data points from four sources), compared with US$943.57 per year for the conventional practice (based on the 30 data points from 12 sources).
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 annual cropping 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 agriculture/regenerative annual cropping practice is assigned third-level priority for nondegraded cropland of minimal slopes. Only rice-based solutions are more highly prioritized.
Total adoption in Scenario 1 is 221.3million hectares in 2050, representing 32 percent of the total suitable land. Of this, 209.53 million hectares are adopted from 2020-2050. The emissions impact of this scenario is 14.52 gigatons carbon dioxide-equivalent reduced by 2050. Net cost is US$77.9billion. Lifetime savings in net profit is US$135.8 billion and operational cost is US$2.3 trillion. Yield reduction of 169 million metric tons is accounted between 2020 and 2050.
Total adoption in the Scenario 2 is 321.9 million hectares in 2050, representing 47 percent of the total suitable land. Of this, 310.12 million hectares are adopted from 2020 to 2050. The impact of this scenario is 22.27 gigatons carbon dioxide-equivalent by 2050. Net cost is US$115.8 billion. Lifetime savings in net profit is US$206.4 billion, and operational cost is US$3.5 trillion. Yield reduction of 259 million metric tons is accounted between 2020 and 2050.
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). Griscom et al (2017)’s “Natural climate solutions” calculate 0.31–0.52 gigatons of carbon dioxide equivalent per year in 2030 for cover cropping, one of the six practice of regenerative annual cropping. The Drawdown model shows 0.3–0.5 gigatons 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.
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 annual cropping 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.
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.
 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 nondegraded 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.
 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.
 All monetary values are presented in 2014 US$.