Perennial crop

Perennial crops are crops that – unlike annual crops – don't need to be replanted each year.[1][2] After harvest, they automatically grow back. By eliminating replanting, perennial cropping can reduce topsoil losses due to erosion,[3] increase biological carbon sequestration[4] due to reduced soil-disturbing tillage, and greatly reduce waterway pollution through agricultural runoff due to less nitrogen input.

Mechanisms
  • Erosion control: Because plant materials (stems, crowns, etc.) can remain in place year-round, topsoil erosion due to wind and rainfall/irrigation is reduced[5]
  • Water-use efficiency: Because these crops tend to be deeper and more fibrously-rooted than their annual counterparts, they are able to hold onto soil moisture more efficiently,[6] while filtering pollutants (e.g. excess nitrogen) traveling to groundwater sources.[7]
  • Nutrient cycling efficiency: Because perennials more efficiently take up nutrients as a result of their extensive root systems,[2] reduced amounts of nutrients need to be supplemented,[8] lowering production costs while reducing possible excess sources of fertilizer runoff.
  • Light interception efficiency: Earlier canopy development and longer green leaf duration increase the seasonal light interception efficiency of perennials, an important factor in plant productivity.[9]
  • Carbon sequestration: Because perennial grasses use a greater fraction of carbon to produce root systems, more carbon is integrated into soil organic matter, contributing to increases in soil organic carbon stocks.[10]

Example crops
  • Miscanthus giganteus - a perennial crop with high yields and high GHG mitigation potential.
  • Perennial sunflower - a perennial oil and seedcrop developed through backcrossing genes with wild sunflower.
  • Perennial grain - more extensive root systems allow for more efficient water and nutrient uptake, while reducing erosion due to rain and wind year-round.
  • Perennial rice - currently in the development stage using similar methods to those used in producing the perennialized sunflower, perennial rice promises to reduce deforestation through increases in production efficiency by keeping cleared land out of the fallow stage for long periods of time.[11]

See also

References
  1. Berry, Wendell (5 January 2009). "A 50-Year Farm Bill". The New York Times. Retrieved 25 March 2011.
  2. "The Perennialization Project: Perennials as a Pathway to Sustainable Agricultural Landscapes in the Upper Midwestern U.S." Iowa State University. Retrieved 25 March 2011.
  3. Wahlquist, Asa. "Perennial crops a win for food security". The Australian. Retrieved 24 March 2011.
  4. Read "Negative Emissions Technologies and Reliable Sequestration: A Research Agenda" at NAP.edu.
  5. Rich, Deborah (24 November 2007). "Perennial crops: The garden that keeps giving". SFGate.com. Retrieved 25 March 2011.
  6. "Perennial Grain Cropping Research: Why Perennial Grain Crops?". The Land Institute. Archived from the original on 15 April 2013. Retrieved 25 March 2011.
  7. Zhou, X. (2010). "Perennial filter strips reduce nitrate levels in soil and shallow groundwater after grassland-to-cropland conversion". Journal of Environmental Quality. 39 (6): 2006–15. doi:10.2134/jeq2010.0151. PMID 21284298.
  8. Glover, J. "Increased Food and Ecosystem Security via Perennial Grains". ScienceMag. Retrieved 26 March 2011.
  9. Dohleman, F. G.; Long, S. P. (2009). "More Productive Than Maize in the Midwest: How Does Miscanthus Do It?". Plant Physiol. 150 (4): 2104–2115. doi:10.1104/pp.109.139162. PMC 2719137. PMID 19535474.
  10. Read "Negative Emissions Technologies and Reliable Sequestration: A Research Agenda" at NAP.edu.
  11. de Rouw, A. "The adaptation of upland rice cropping to ever-shorter fallow periods and its limit" (PDF). Poverty reduction and shifting cultivation stabilisation in the uplands of Lao PDR: technologies, approaches and methods for improving upland Livelihoods – Proceedings of a workshop held in Luang Prabang, Lao PDR. National Agriculture and Forestry Research Institute. Vientiane, Lao PDR pp. 139–148. Archived from the original (PDF) on 21 July 2011. Retrieved 25 March 2011.
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