Integrating Legumes into Southern Pine Forests

Saturday, December 13, 2025 8:12 PM

Integrating Legumes into Southern Pine Forests 

Supports Tree Growth and Carbon Capture While Producing Sustainable Food for a Hungry Planet

 

Ernest Rogers, Vice Chair, UVEF

Executive Summary

Southern U.S. timber farms face a unique opportunity: to combine timber production with protein-rich food crops in an agroforestry system that enhances profitability, sustainability, and global food security. By interplanting legumes such as peas within southern pine stands, farms can:

  • Increase protein production without expanding agricultural land.
  • Reduce reliance on synthetic fertilizers, cutting carbon emissions from fertilizer manufacturing.
  • Enhance carbon sequestration, as diversified systems store more biomass and soil carbon.
  • Diversify revenue streams, adding food crop sales to timber income.

This article outlines the ecological, economic, and social benefits of adopting legume-pine intercropping in the southern U.S. timber sector.

Pilot Projection: A 100-acre pilot study could generate ~$36,000 net annual benefit, or ~$180,000 over five years, even under conservative assumptions.

By adopting this innovation, southern U.S. timber farms can position themselves as leaders in climate-smart forestry, delivering triple returns: food, carbon, and profit.

Can this be an answer to the question of how to conquer world hunger?

Background & Rationale

  • Global protein demand: Protein deficiency affects billions worldwide. Legumes are a cost-effective, climate-smart source of plant protein.
  • Environmental impact of fertilizer: Fertilizer production contributes significantly to greenhouse gas emissions. Legumes naturally fix nitrogen, reducing the need for synthetic inputs.
  • Agroforestry precedent: Research shows intercropping legumes with trees improves soil fertility, biodiversity, and resilience. Trials in pea-based agroforestry systems demonstrate increased carbon storage and food yields.

Proposed System

  1. Species selection:
    • Primary crop: Trees, such as loblolly pine and southern yellow pine
    • Intercrop: Peas or other protein-rich legumes adapted to forest soils. (Good choice is yellow field pea(Pisum sativum subsp. arvense),
  1. Planting design:
    • Legumes sown between pine rows, especially in early- to mid-rotation stands where light penetration is sufficient.
    • Rotational planting to maintain soil fertility and maximize nitrogen fixation.
  2. Management practices:
    • Minimal fertilizer inputs, relying on legumes for nitrogen.
    • Soil and foliage testing to monitor nutrient dynamics.
    • Harvesting peas for food markets while maintaining timber growth.

Benefits

Environmental

  • Carbon sequestration: Intercropping increases above- and below-ground biomass, enhancing carbon storage.
  • Reduced emissions: Lower fertilizer use cuts greenhouse gas emissions from production and application.
  • Soil health: Legumes improve organic matter, microbial diversity, and nutrient cycling.

Economic

  • Diversified income: Timber farms gain a secondary revenue stream from pea harvests.
  • Risk management: Diversification buffers against timber price fluctuations.
  • Cost savings: Reduced fertilizer inputs lower operational expenses.

Social

  • Food security: Protein-rich legumes contribute to local and global diets.
  • Sustainability: Providing renewable .

Implementation Plan

  1. Pilot plots: Establish demonstration plots (100–200 acres) intercropping peas with pine.
  2. Monitoring: Track nitrogen fixation, soil carbon, timber growth, and pea yields.
  3. Economic analysis: Compare costs and revenues against conventional fertilized and unfertilized pine stands.
  4. Scaling: Expand successful practices across larger plantation areas.


Financial Projection: 100-Acre Pilot Intercropping Peas with Pine

Assumptions

  • Timber baseline: Southern pine plantation managed for sawtimber, mid-rotation fertilization typically required.
  • Pea yield: ~1,500 lbs/acre
  • Market price for peas: $0.25/lb (bulk food-grade peas).
  • Fertilizer savings: $50/acre annually (reduced nitrogen inputs).
  • Carbon credit potential: $10/acre annually (voluntary carbon markets, based on added sequestration).


Cost-Benefit Analysis (Annualized, Pilot Scale)

Revenue/Cost Item

Per Acre

100 Acres

 Notes

Pea sales revenue

$375

$37,500

1,500 lbs × $0.25/lb

Fertilizer savings

$50

$5,000

Reduced nitrogen inputs

Carbon credit revenue

$10

$1,000

Conservative estimate

Added management costs

-$75

-$7,500

Labor, seed, equipment

Net annual benefit

$360

$36,000

Combined food + savings + credits


5-Year Pilot (100 Acres): 

Year

Pea Revenue

Fertilizer Savings

Carbon Credits

Added Costs

Net Benefit

1

$37,500

$5,000

$1,000

-$7,500

$36,000

2

$37,500

$5,000

$1,000

-$7,500

$36,000

3

$37,500

$5,000

$1,000

-$7,500

$36,000

4

$37,500

$5,000

$1,000

-$7,500

$36,000

5

$37,500

$5,000

$1,000

-$7,500

$36,000

5-yr Total

$187,500

$25,000

$5,000

- $37,500

$180,000


Key Insights

  • Profitability: Even under conservative assumptions, the pilot generates ~$36,000 net benefit annually, or ~$180,000 over five years.
  • Diversification: Pea sales provide a steady cash flow independent of timber harvest cycles.
  • Sustainability: Fertilizer savings and carbon credits strengthen the farm’s environmental profile.
  • Scalability: Expanding to 1,000 acres could yield ~$1.8 million net benefit over five years.

Conclusion

Intercropping in managed forest lands is not only environmentally beneficial but also economically viable. For a diversified southern U.S. timber farm, it offers a pathway to triple returns: food production, carbon reduction, and enhanced profitability.


References

Kristina Connor, Rebecca Barlow, Luben Dimov, and Martin Smith. “Longleaf Pine Agroforestry.” In Proceedings of the 16th Biennial Southern Silvicultural Research Conference, edited by John R. Butnor, 71–75. Asheville, NC: USDA Forest Service, Southern Research Station, 2012.
https://research.fs.usda.gov/treesearch/41379

Sabrina Greer. “Agroforestry: Working Toward Diverse Intercropping.” UF/IFAS Extension Panhandle Agriculture, April 17, 2020.
https://nwdistrict.ifas.ufl.edu/phag/2020/04/17/agroforestry-working-toward-diverse-intercropping/

Abebe Ebbisa. “Mechanisms Underlying Cereal/Legume Intercropping as Nature-Based Biofortification: A Review.” Food Production, Processing and Nutrition 4, no. 19 (2022).
https://fppn.biomedcentral.com/articles/10.1186/s43014-022-00096-y

Anil Keprate, D. R. Bhardwaj, P. Sharma, D. Kumar, and R. K. Rana. “Biomass Partitioning, Carbon Storage, and Pea (Pisum sativum L.) Crop Production under a Grewia optiva-Based Agroforestry System in the Mid-Hills of the Northwestern Himalayas.” Sustainability 16, no. 17 (2024): 7438.
https://www.mdpi.com/2071-1050/16/17/7438

Qiang Wang, Qing Chai, Xiaodong Dou, Wen Yin, Yanan Sun, Feng Hu, Hong Li, Zhen Liu, Jian Wei, and Xia Xu. “Microbial Mechanism of Soil Carbon Emission Reduction in Maize-Pea Intercropping System with No Tillage in Arid Land Areas of Northwestern China.” Frontiers in Sustainable Food Systems 8 (2024).
https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2024.1415264/full

Institute of Agricultural Resources and Regional Planning (IARRP), Chinese Academy of Agricultural Sciences (CAAS). “Impacts of Long-Term Maize and Green Manure Pea Intercropping on Maize Production and Subsoil Carbon Storage and Greenhouse Gas Emissions.” 2023.
https://iarrp.caas.cn/en/news/updates/f646866ea0c0476d99d2bb2bb783db50.htm

Tejendra Chapagain and Andrew Riseman. “Barley–Pea Intercropping: Effects on Land Pro-ductivity, Carbon and Nitrogen Transformations.” Field Crops Research 166 (2014): 18–25.
https://www.researchgate.net/profile/Andrew-Riseman/publication/263892906_Barley-pea_intercropping_Effects_on_land_productivity_carbon_and_nitrogen_transformations/links/5c85637c299bf1268d4f8836/Barley-pea-intercropping-Effects-on-land-productivity-carbon-and-nitrogen-transformations.pdf



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