Villagers handle seedlings during a permagarden planting, a training sponsored by CAFWA, Community Action Fund for Women in Africa.
Technical Summary

Abandoned Farmland Restoration

Project Drawdown describes abandoned farmland restoration as: a set of processes for restoring degraded, abandoned land to productivity and biosequestration. This solution replaces the conventional practice of abandoning degraded grassland.

Abandonment of farmland have been increased in the last two centuries. The failure of these lands to continue to produce the desired economic benefits has forced the land owners to abandon them. The loss of the agricultural productivity of these lands poses a serious threat to food security. These lands have also lost substantial carbon from soil and biomass in the process of becoming degraded.

Restoring these lands to productivity sequesters carbon, while bringing land back into production. This can also result in substantial reduced emissions from avoided deforestation, though that impact is not modeled here. This model looks only at agricultural restoration, though restoration to forests and other ecosystems is also practiced on abandoned farmland.

Given the urgency of preventing emissions from deforestation, and the pressure of meeting food demand given the trend towards increasing meat consumption, abandoned farmland restoration is highly desirable. Its impressive carbon sequestration impact, along with these co-benefits, makes it an essential component of mitigation efforts.

Methodology

Total Land Area[1]

The total available land for the abandoned farmland restoration solution is 371 million hectares,[2] which is allocated on degraded grasslands. Though abandoned land that has been restored is by definition now in agricultural production or is a restored forest or other ecosystem, 20 million hectares are reported to be under active restoration in globally; thus, this number is used as current adoption[3] of abandoned farmland restoration.

It is assumed that the process of restoration takes one year, after which the land returns to production. Restored land is assumed to be in Drawdown’s regenerative annual cropping solution, as the majority of restoration measures are based on improving soil fertility through organic inputs. This area, however, is not included in the total adoption area for the regenerative annual cropping solution.

Adoption Scenarios[4]

Projections on restoration of abandoned farmland are unavailable. However, abandoned farmland is a subset of degraded farmland, for which published targets are available. Thus, six custom adoption scenarios were developed, based on the Intergovernmental Panel on Climate Change (IPCC),United Nations Environment Program (UNEP)’s 2013 low and high targets for restoration of degraded land and historical trends available for China, EU, and Kazahkstan. In the absence of targeted data, this study assumes that both abandoned and degraded land will follow similar trends.

Impacts of increased adoption of abandoned farmland restoration from 2020-2050 were generated based on two growth scenarios, which were assessed in comparison to a Reference Scenario where the solution’s market share was fixed at the current levels.

  • Scenario 1: The analysis of these custom scenarios shows restoration of 189.5million hectares of abandoned farmland.
  • Scenario 2: Aggressive adoption of abandoned farmland restoration yields restoration of 296.1 million hectares of abandoned farmland.

Sequestration Model

Carbon sequestration rates are set at 1.3 tons per hectare per year, based on meta-analysis of 31 data points from 4 sources.

Financial Model

First cost for the abandoned farmland restoration solution is US$561.6 per hectare,[5] based on meta-analysis of 17 data points from 5 sources. There is no conventional first cost for comparison, as the land is assumed to have been abandoned for some time. The net profit margin and operational cost is taken from the regenerative annual cropping model, as it is assumed that this solution will eventually adopt regenerative annual cropping practices.

Integration[6]

In the process of allocating land to solutions by Agro-Ecological Zone, it was assumed that abandoned farmland is currently degraded grassland.

Results

Total adoption in the Scenario 1 is 189.5 million hectares in 2050, representing 51 percent of the total available land. Of this, 169.48 million hectares are adopted from 2020-2050. The sequestration impact of this scenario is 12.48 gigatons of carbon dioxide-equivalent by 2050. Marginal first cost is US$98.2 billion and lifetime operational cost is US$3.2 trillion. Net savings is US$2.6 trillion. Total yield of food from this previously abandoned land is 9.2 billion metric tons between 2020-2050.

Total adoption in the Scenario 2 is 296.1 million hectares in 2050, representing 80 percent of the total available land. Of this, 276.09 million hectares are adopted from 2020-2050. The impact of this scenario is 20.32 gigatons of carbon dioxide-equivalent by 2050. Marginal first cost is US$159.9 billion and lifetime operational cost is US$5.2 trillion. Net savings is US$4.3 trillion. Total yield of food from this previously abandoned land is 15 billion metric tons between 2020-2050.

Discussion

Benchmarks

Projected impacts for this solution align very closely with IPCC projections for the restoration of degraded land. The IPCC estimates an impact of 0.1-0.7 gigatons of carbon dioxide-equivalent per year by 2030 (Smith, 2007), while the Drawdown model shows 0.3-0.5 gigatons per year in 2030, well within the benchmark range.

Limitations

For future upgrades of this solution, it would be useful to further investigate how “abandoned farmland” is categorized and how it is distinct from degraded lands in general.

Conclusions

It should be seen as somewhat embarrassing for humanity that we continue to clear land for agriculture while leaving degraded, once-fertile lands behind in an abandoned state. The multiple mitigation benefits associated with abandoned farmland restoration provide strong incentive to bring these lands back into production and care for them thereafter.

 

[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.