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. Many fruit and nut crops are naturally perennial, however there is also a growing movement to create perennial alternatives to annual crops. From the 1920s to the 1950s, researchers in the former Soviet Union attempted to perennialize annual wheats by crossing them with perennial relatives such as intermediate wheatgrass. Interest waned when the crosses repeatedly resulted in sterile offspring, and seed yield decreased significantly. The next major time the project of perennializing grain was picked up was a wheat hybrid developed by the Montana Agricultural Experiment Station in 1986, which the Rodale Institute field tested.[3] For example, The Land Institute has bred a perennial wheat crop known as Kernza. By eliminating or greatly reducing the need for tillage, perennial cropping can reduce topsoil losses due to erosion,[4] increase biological carbon sequestration,[5] and greatly reduce waterway pollution through agricultural runoff due to less nitrogen input.

Benefits
  • Erosion control: Because plant materials (stems, crowns, etc.) can remain in place year-round, topsoil erosion due to wind and rainfall/irrigation is reduced[6]
  • 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,[7] while filtering pollutants (e.g. excess nitrogen) traveling to groundwater sources.[8]
  • 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,[9] 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.[10]
  • 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.[5]
  • Perennial species have been shown to provide an opportunity for mitigating or reducing the negative effects of climate change while sustaining their agricultural productivity as well.[11] It has also been shown that perennial plant communities may also enhance ecosystem resilience. As well as stability and ability to adapt to environmental fluctuations, due to them possessing high levels of biodiversity.[12]

Examples

Existing crops

Under development
  • 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.[13]

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. Wagoner, Peggy; Schaeffer, Jurgen R. (January 1, 1990). "Perennial grain development: Past efforts and potential for the future". Critical Reviews in Plant Sciences. 9 (5): 381–408. doi:10.1080/07352689009382298.
  4. Wahlquist, Asa. "Perennial crops a win for food security". The Australian. Retrieved 24 March 2011.
  5. "Terrestrial Carbon Removal and Sequestration". Negative Emissions Technologies and Reliable Sequestration: A Research Agenda. National Academies Press. 2019. pp. 87–136. ISBN 978-0-309-48452-7.
  6. Rich, Deborah (24 November 2007). "Perennial crops: The garden that keeps giving". SFGate.com. Retrieved 25 March 2011.
  7. "Perennial Grain Cropping Research: Why Perennial Grain Crops?". The Land Institute. Archived from the original on 15 April 2013. Retrieved 25 March 2011.
  8. 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.
  9. Glover, J. D.; Reganold, J. P.; Bell, L. W.; Borevitz, J.; Brummer, E. C.; Buckler, E. S.; Cox, C. M.; Cox, T. S.; Crews, T. E.; Culman, S. W.; DeHaan, L. R.; Eriksson, D.; Gill, B. S.; Holland, J.; Hu, F.; Hulke, B. S.; Ibrahim, A. M. H.; Jackson, W.; Jones, S. S.; Murray, S. C.; Paterson, A. H.; Ploschuk, E.; Sacks, E. J.; Snapp, S.; Tao, D.; Van Tassel, D. L.; Wade, L. J.; Wyse, D. L.; Xu, Y. (24 June 2010). "Increased Food and Ecosystem Security via Perennial Grains". Science. 328 (5986): 1638–1639. doi:10.1126/science.1188761. PMID 20576874. S2CID 130815466.
  10. Dohleman, Frank G.; Long, Stephen P. (August 2009). "More Productive Than Maize in the Midwest: How Does Miscanthus Do It?". Plant Physiology. 150 (4): 2104–2115. doi:10.1104/pp.109.139162. PMC 2719137. PMID 19535474.
  11. Zan, Claudia S; Fyles, James W; Girouard, Patrick; Samson, Roger A (2001-08-01). "Carbon sequestration in perennial bioenergy, annual corn and uncultivated systems in southern Quebec". Agriculture, Ecosystems & Environment. 86 (2): 135–144. doi:10.1016/S0167-8809(00)00273-5. ISSN 0167-8809.
  12. Jackson, L. E.; Pascual, U.; Hodgkin, T. (2007-07-01). "Utilizing and conserving agrobiodiversity in agricultural landscapes". Agriculture, Ecosystems & Environment. Biodiversity in Agricultural Landscapes: Investing without Losing Interest. 121 (3): 196–210. doi:10.1016/j.agee.2006.12.017. ISSN 0167-8809.
  13. Rouw, Anneke de; Soulilad, B.; Phanthavong, K.; Dupin, B. (2005). "The adaptation of upland rice cropping to ever-shorter fallow periods and its limit". In Bouahom, B.; Glendinning, A.; Nilsson, S.; Victor, M. (eds.). Poverty reduction and shifting cultivation stabilization in the uplands of Lao PDR. CiteSeerX 10.1.1.538.3332. hdl:10568/37412. OCLC 169891017.
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