1. ** ^  ** Berry, Wendell (5 January 2009). [ "A 50-Year Farm Bill" ](https://www.nytimes.com/2009/01/05/opinion/05berry.html?_r=1) . _The New York Times_ . Retrieved  25 March  2011  . 
  2. ^  _**a** _ _**b** _ [ "The Perennialization Project: Perennials as a Pathway to Sustainable Agricultural Landscapes in the Upper Midwestern U.S." ](http://www.nrem.iastate.edu/landscape/projects/perennial/perennial.html) Iowa State University  . Retrieved  25 March  2011  . 
  3. ** ^  ** [ "Perennial agriculture | Benefits, Practices & Challenges" ](https://www.britannica.com/topic/perennial-agriculture) . _www.britannica.com_ . Retrieved  2023-12-05  . 
  4. ^  _**a** _ _**b** _ Monfreda, Chad; Ramankutty, Navin; Foley, Jonathan A. (March 2008). [ "Farming the planet: 2. Geographic distribution of crop areas, yields, physiological types, and net primary production in the year 2000" ](https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2007GB002947) . _Global Biogeochemical Cycles_ . **22** (1). [ Bibcode ](/wiki/Bibcode_\(identifier\) "Bibcode \(identifier\)") : [ 2008GBioC..22.1022M ](https://ui.adsabs.harvard.edu/abs/2008GBioC..22.1022M) . [ doi ](/wiki/Doi_\(identifier\) "Doi \(identifier\)") :  [ 10.1029/2007GB002947 ](https://doi.org/10.1029%2F2007GB002947) . [ ISSN ](/wiki/ISSN_\(identifier\) "ISSN \(identifier\)") [ 0886-6236 ](https://www.worldcat.org/issn/0886-6236) . [ S2CID ](/wiki/S2CID_\(identifier\) "S2CID \(identifier\)") [ 128794303 ](https://api.semanticscholar.org/CorpusID:128794303) . 
  5. ** ^  ** Ramírez-Ojeda, Gabriela; Peralta, Iris E.; Rodríguez-Guzmán, Eduardo; Chávez-Servia, José Luis; Sahagún-Castellanos, Jaime; Rodríguez-Pérez, Juan Enrique (2021-04-23). [ "Climatic Diversity and Ecological Descriptors of Wild Tomato Species (Solanum sect. Lycopersicon) and Close Related Species (Solanum sect. Juglandifolia y sect. Lycopersicoides) in Latin America" ](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8145878) . _Plants_ . **10** (5): 855. [ doi ](/wiki/Doi_\(identifier\) "Doi \(identifier\)") :  [ 10.3390/plants10050855 ](https://doi.org/10.3390%2Fplants10050855) . [ ISSN ](/wiki/ISSN_\(identifier\) "ISSN \(identifier\)") [ 2223-7747 ](https://www.worldcat.org/issn/2223-7747) . [ PMC ](/wiki/PMC_\(identifier\) "PMC \(identifier\)") [ 8145878 ](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8145878) . [ PMID ](/wiki/PMID_\(identifier\) "PMID \(identifier\)") [ 33922706 ](https://pubmed.ncbi.nlm.nih.gov/33922706) . 
  6. ** ^  ** Poppenwimer, Tyler; Mayrose, Itay; DeMalach, Niv (2023-11-08). [ "Revising the global biogeography of annual and perennial plants" ](https://www.nature.com/articles/s41586-023-06644-x) . _Nature_ . **624** (7990): 109–114. [ arXiv ](/wiki/ArXiv_\(identifier\) "ArXiv \(identifier\)") :  [ 2304.13101 ](https://arxiv.org/abs/2304.13101) . [ doi ](/wiki/Doi_\(identifier\) "Doi \(identifier\)") : [ 10.1038/s41586-023-06644-x ](https://doi.org/10.1038%2Fs41586-023-06644-x) . [ ISSN ](/wiki/ISSN_\(identifier\) "ISSN \(identifier\)") [ 1476-4687 ](https://www.worldcat.org/issn/1476-4687) . [ PMID ](/wiki/PMID_\(identifier\) "PMID \(identifier\)") [ 37938778 ](https://pubmed.ncbi.nlm.nih.gov/37938778) . [ S2CID ](/wiki/S2CID_\(identifier\) "S2CID \(identifier\)") [ 260332117 ](https://api.semanticscholar.org/CorpusID:260332117) . 
  7. ** ^  ** [ "Perennial Grain Crop Development" ](https://landinstitute.org/our-work/perennial-crops/) . _The Land Institute_ . Retrieved  2023-12-05  . 
  8. ** ^  ** 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. [ Bibcode ](/wiki/Bibcode_\(identifier\) "Bibcode \(identifier\)") : [ 1990CRvPS...9..381W ](https://ui.adsabs.harvard.edu/abs/1990CRvPS...9..381W) . [ doi ](/wiki/Doi_\(identifier\) "Doi \(identifier\)") : [ 10.1080/07352689009382298 ](https://doi.org/10.1080%2F07352689009382298) . 
  9. ** ^  ** Wahlquist, Asa. [ "Perennial crops a win for food security" ](http://www.theaustralian.com.au/higher-education/perennial-crops-a-win-for-food-security/story-e6frgcjx-1225885860575) . The Australian  . Retrieved  24 March  2011  . 
  10. ^  _**a** _ _**b** _ [ "Terrestrial Carbon Removal and Sequestration" ](https://www.nap.edu/read/25259/chapter/5) . _Negative Emissions Technologies and Reliable Sequestration: A Research Agenda_ . National Academies Press. 2019. pp. 87–136. [ ISBN ](/wiki/ISBN_\(identifier\) "ISBN \(identifier\)") [ 978-0-309-48452-7  ](/wiki/Special:BookSources/978-0-309-48452-7 "Special:BookSources/978-0-309-48452-7") . 
  11. ** ^  ** Rich, Deborah (24 November 2007). [ "Perennial crops: The garden that keeps giving" ](http://articles.sfgate.com/2007-11-24/home-and-garden/17268607_1_perennial-vegetables-doug-gosling-garden) . SFGate.com  . Retrieved  25 March  2011  . 
  12. ** ^  ** [ "Perennial Grain Cropping Research: Why Perennial Grain Crops?" ](https://archive.today/20130415064658/http://www.landinstitute.org/vnews/display.v/ART/2007/03/15/45fac62e11c35) . The Land Institute. Archived from [ the original ](http://www.landinstitute.org/vnews/display.v/ART/2007/03/15/45fac62e11c35) on 15 April 2013  . Retrieved  25 March  2011  . 
  13. ** ^  ** Zhou, X. (2010). [ "Perennial filter strips reduce nitrate levels in soil and shallow groundwater after grassland-to-cropland conversion" ](https://lib.dr.iastate.edu/abe_eng_pubs/318) . _Journal of Environmental Quality_ . **39** (6): 2006–15. [ doi ](/wiki/Doi_\(identifier\) "Doi \(identifier\)") : [ 10.2134/jeq2010.0151 ](https://doi.org/10.2134%2Fjeq2010.0151) . [ PMID ](/wiki/PMID_\(identifier\) "PMID \(identifier\)") [ 21284298 ](https://pubmed.ncbi.nlm.nih.gov/21284298) . 
  14. ** ^  ** 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 ](/wiki/Doi_\(identifier\) "Doi \(identifier\)") : [ 10.1126/science.1188761 ](https://doi.org/10.1126%2Fscience.1188761) . [ PMID ](/wiki/PMID_\(identifier\) "PMID \(identifier\)") [ 20576874 ](https://pubmed.ncbi.nlm.nih.gov/20576874) . [ S2CID ](/wiki/S2CID_\(identifier\) "S2CID \(identifier\)") [ 130815466 ](https://api.semanticscholar.org/CorpusID:130815466) . 
  15. ** ^  ** Dohleman, Frank G.; Long, Stephen P. (August 2009). [ "More Productive Than Maize in the Midwest: How Does Miscanthus Do It?" ](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2719137) . _Plant Physiology_ . **150** (4): 2104–2115. [ doi ](/wiki/Doi_\(identifier\) "Doi \(identifier\)") : [ 10.1104/pp.109.139162 ](https://doi.org/10.1104%2Fpp.109.139162) . [ PMC ](/wiki/PMC_\(identifier\) "PMC \(identifier\)") [ 2719137 ](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2719137) . [ PMID ](/wiki/PMID_\(identifier\) "PMID \(identifier\)") [ 19535474 ](https://pubmed.ncbi.nlm.nih.gov/19535474) . 
  16. ** ^  ** 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" ](https://www.sciencedirect.com/science/article/pii/S0167880900002735) . _Agriculture, Ecosystems & Environment _ . **86** (2): 135–144. [ doi ](/wiki/Doi_\(identifier\) "Doi \(identifier\)") : [ 10.1016/S0167-8809(00)00273-5 ](https://doi.org/10.1016%2FS0167-8809%2800%2900273-5) . [ ISSN ](/wiki/ISSN_\(identifier\) "ISSN \(identifier\)") [ 0167-8809 ](https://www.worldcat.org/issn/0167-8809) . 
  17. ** ^  ** Jackson, L. E.; Pascual, U.; Hodgkin, T. (2007-07-01). [ "Utilizing and conserving agrobiodiversity in agricultural landscapes" ](https://www.sciencedirect.com/science/article/pii/S0167880906004440) . _Agriculture, Ecosystems & Environment _ . Biodiversity in Agricultural Landscapes: Investing without Losing Interest. **121** (3): 196–210. [ doi ](/wiki/Doi_\(identifier\) "Doi \(identifier\)") : [ 10.1016/j.agee.2006.12.017 ](https://doi.org/10.1016%2Fj.agee.2006.12.017) . [ ISSN ](/wiki/ISSN_\(identifier\) "ISSN \(identifier\)") [ 0167-8809 ](https://www.worldcat.org/issn/0167-8809) . 
  18. ** ^  ** 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 ](/wiki/CiteSeerX_\(identifier\) "CiteSeerX \(identifier\)") [ 10.1.1.538.3332 ](https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.538.3332) . [ hdl ](/wiki/Hdl_\(identifier\) "Hdl \(identifier\)") : [ 10568/37412 ](https://hdl.handle.net/10568%2F37412) . [ OCLC ](/wiki/OCLC_\(identifier\) "OCLC \(identifier\)") [ 169891017 ](https://www.worldcat.org/oclc/169891017) .