February 10, 2022
By Jane Coghlan, Swette Center Student Worker.
Can you envision the value and versatility of a food that can grow in any climate, is highly nutritious, requires low water input, can self-fertilize, and has a long shelf-life? These are the prominent advantages of an ancient food called pulses. Pulses are among the first plants to be domesticated by humans for sustenance, in turn making them a fundamental ingredient in recipes across old and new cultures in every continent (FAO, 2016, pg. 12-13). The UN Food and Agriculture Organization (FAO) has designated today, February 10, as World Pulses Day to celebrate the extensive benefits of this resilient food.
In cooking, the most commonly used pulses are dry beans, lentils, chickpeas, and dry peas. They are classified as legumes, however, pulses are specifically the dried edible seeds found inside the legume plant (Harvard School of Public Health, 2020). Pulses are unique from other edible legume plants because they are high in protein while being very low in fat (Marinangeli et al., 2017). According to the FAO, they contain a high amount of complex carbohydrates, iron, potassium, folate, and fiber which all help the body maintain proper health (FAO, 2016, pg. 38). They also have antioxidative properties that decrease risks of diet-related chronic diseases such as obesity, heart disease, and diabetes (Kumar and Pandey, 2020; The Lancet, 2019).
Not only are pulses unique being one of the most nutritious crops in the world, but they are also exceptionally environmentally sustainable. Pulses require very little water to grow, which is a crucial feature in considering sustainability because agricultural irrigation is currently responsible for roughly 70% of global freshwater use (FAO, 2016, pg. 39; Pimental et al., 2004). This freshwater use percentage would see a decrease if pulses were more commonly used in crop rotations. Over time, pulses have adapted to survive on low amounts of water, and many pulse crops have roots that go deep in the soil to avoid competing with other plants for moisture (FAO, 2016, pg. 39).
Another sustainable characteristic of pulses is that they do not need high amounts of fertilization due to their ability to fix nitrogen into the soil (Stagnari et al., 2017). Most plants uptake nitrogen and leave the soil depleted, but pulse crops take atmospheric nitrogen and sequester it into the soil. Bacteria in the soil then convert it to ammonia, which is the available form of nitrogen for plants (Killpack and Buchholz, 1993). The bacteria exchange ammonia with carbohydrates from the plants in a mutualistic relationship (FAO, 2016, pg. 40). Through this process, nitrogen is sequestered and soil fertility is increased. Some varieties of pulses can fix 30-40 kg of nitrogen per hectare of land (FAO, 2016, pg. 40). When pulses are used as cover crops and forage for grazing livestock, the potential for nitrogen sequestration can get up to 300 kg of nitrogen per hectare (FAO, 2016, pg. 40). Planting more pulses would greatly reduce the need to use synthetic nitrogen fertilizers which commonly runoff the surface of fields and severely damage aquatic ecosystems (Pimentel et al., 2004). Synthetic fertilizers also adversely affect soil biodiversity because they deliver ammonia directly to the plant, and therefore, the plant no longer needs to feed the microorganisms in the soil (Brown, 2019, pg. 31).
It is clear why pulses have been a staple food all throughout the world since humans began farming. The extensive nutritional and environmental benefits including their high protein and low fat content, minimal water requirements, and ability to fix nitrogen into the soil are compelling factors as to why pulses should be more involved in our modern food system. Furthermore, in today’s world of climate change and increasing extreme weather, a versatile and resilient crop like pulses are extra vital. In our current food system, consumers create the demand for which crops are grown through their food purchases. The potential for pulses to create a healthier and more sustainable food system is ample, however, the process starts in each of our very own kitchens and recipes.
Sources:
Brown, G. (2018). Dirt to soil: one family's journey into regenerative agriculture. Chelsea Green Publishing.
FAO. (2016). Pulses: nutritious seeds for a sustainable future. Rome.
Harvard School of Public Health. (2020, October 16). Legumes and Pulses. The Nutrition Source. https://www.hsph.harvard.edu/nutritionsource/legumes-pulses/#:~:text=A%20legume%2 0refers%20to%20any,the%20pod%20is%20the%20pulse.
Killpack, S. C. and Buchholz, D. (1993, October). Nitrogen in the Environment: Nitrogen Cycle. University of Missouri Extension. https://extension.missouri.edu/publications/wq252#:~:text=The%20main%20source%20o f%20nitrogen%20in%20soils%20is%20from%20organic%20matter.&text=It%20sh ows%20nitrogen%20changing%20from,into%20forms%20plants%20can%20use.
Kumar, S., & Pandey, G. (2020). Biofortification of pulses and legumes to enhance nutrition. Heliyon, 6(3). https://doi.org/10.1016/j.heliyon.2020.e03682
The Lancet. (2019, April 3). Globally, one in five deaths are associated with poor diet. ScienceDaily. Retrieved March 4, 2021 from www.sciencedaily.com/releases/2019/04/190403193702.htm
Marinangeli, C., Curran, J., Barr, S., Slavin, J., Puri, S., Swaminathan, S., Tapsell, L., & Patterson, C. (2017). Enhancing nutrition with pulses: defining a recommended serving size for adults. Nutrition Reviews, 75(12), 990–1006. https://doi.org/10.1093/nutrit/nux058
Pimentel, D., Berger, B., Filiberto, D., Newton, M., Wolfe, B., Karabinakis, E., Clark, S., Poon, E., Abbett, E., & Nandagopal, S. (2004). Water Resources: Agricultural and Environmental Issues, BioScience, Volume 54, Issue 10, Pages 909–918. https://doi.org/10.1641/0006-3568(2004)054[0909:WRAAEI]2.0.CO;2
Stagnari, F., Maggio, A., Galieni, A., & Pisante, M. (2017). Multiple benefits of legumes for agriculture sustainability: an overview. Chemical and Biological Technologies in Agriculture, 4(1). https://doi.org/10.1186/s40538-016-0085-1
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