Pulses, a subgroup of legumes, are plant species members of the Leguminosae family (commonly known as the pea family) that produce edible seeds which are used for human and animal consumption.

Only legumes harvested for dry grain are classified as pulses.  Legume species when used as vegetables (e.g. green peas, green beans), for oil extraction (e.g. soybean, groundnut) and for sowing purposes (e.g. clover, alfalfa) are not considered pulses.^[1]

[1] FAO 1994. Definition and classification of commodities: 4. Pulses and derived products. (Accessed 22/10/2015). www.fao.org/es/faodef/fdef04e.htm

Some of the most widely consumed types of pulses include dried grain legumes like kidney beans, navy beans (Phaseolus vulgaris L.), faba beans (Vicia faba L.), chickpeas (Cicer arietinum), dried or split peas (Pisum sativum), mung beans (Vigna radiata L.) cowpeas, black-eyed peas [Vigna unguiculata (L.) Walp.], and several varieties of lentils (Lens culinaris Medik.). There are also many less-known species of pulses such as lupines (e.g. Lupinus albus L., Lupinus mutabilis Sweet) and Bambara beans [Vigna subterranea L. (Verdc.)].

Although the exact number might be unknown, one can estimate that there are hundreds of varieties of pulses, including many local varieties that are not exported or grown worldwide. For example, the International Crop Research Institute for the Semi-Arid Tropics (ICRISAT) reported that 66 and 77 cultivar varieties of pigeon-peas [Cajanus cajan (L.) Huth] and chickpeas, respectively, have been released in different countries.^[1]

[1] ICRISAT 2015. Crops. (Accessed 26/10/2015). www.icrisat.org.

Pulses are important for a number of reasons. Eating pulses regularly can help improve human health and nutrition because of their high protein and mineral content. Including pulses in intercropping farming systems and/or cultivating them as cover crops enhance soil fertility^[1] and reduce dependency on chemical fertilizers by fixing nitrogen and freeing phosphorous, thus contributing to a more sustainable production system.^[2] Pulses are also important for sustaining and maximizing production in pulse-cereal crop rotations. In such rotations, subsequent cereal yield and crude protein concentration can be increased due to the residual nitrogen provided by the previous pulse crop.^[3],[4],[5] However, there is insufficient data and information on the real contribution of pulses to household food security and nutrition. This important issue should be better documented and explored during the International Year of Pulses.

[1] Clark, A. 2007. Managing cover crops profitably. Sustainable Agriculture Network (SAN), Beltsville, USA.
[2] Bohlool, BB; Ladha, JK; Garrity, DP; George, T. 1992. Biological nitrogen fixation for sustainable agriculture: A perspective. Plant and Soil 141:1–11.
[3] Howieson, JG; O’Hara, GW; Carr, SJ. Changing roles of legumes in Mediterranean agriculture: developments from an Australian perspective. Field Crop Research 65:107–122.
[4] Wright, AT. 1990. Yield effect of pulses on subsequent cereal crops in the northern prairies. Canadian Journal of Plant Sciences 70:1023–1032.
[5] Gan, YT; Miller, PR; McConkey; Zentner, RP; Stevenson, FC; McDonald, CL. 2003. Influence of diverse cropping systems on durum wheat yield and protein in the semiarid Northern Great Plains. Agronomy Journal 95:245–252.

Pulses are packed with nutrients, and are a fantastic source of protein, which is particularly important for human health. Pulses are made up of about 20-25 percent of protein by weight, which is double the protein content of wheat and triple that of rice. When eaten together with cereals, the protein quality in the diet is significantly improved and a complete protein is formed.

Pulses have a low fat content and contain zero cholesterol. The Glycaemic Index (an indicator of the effect on blood sugar) is also low in pulses, and they are a significant source of dietary fibre. Since they do not contain gluten, they are an ideal food for celiac patients. Additionally, pulses are rich in minerals (iron*, magnesium, potassium, phosphorus, zinc) and B-vitamins (thiamine, riboflavin, niacin, B₆, and folate) all of which play a vital role in health.

_{*The iron from animal source foods is better used by the body than the iron obtained from pulses. To improve the iron available from pulses, it is advised to combine them with sources of vitamin C, like citrus fruits.}

Pulses are an important part of a healthy diet because they are high in protein, fibre, and other essential nutrients. Their high iron and zinc content is especially beneficial for women and children at risk of anemia. Pulses also contain bioactive compounds that show some evidence of helping to combat cancer, diabetes and heart disease.^[1] Some research indicates that eating pulses regularly can help control and combat obesity as well.^[2]

[1] http://grainlegumes.cgiar.org/why-grain-legumes-matter/improving-nutrition-and-health/
[2] http://www.ncbi.nlm.nih.gov/pubmed/22916815

Pulses are dried seeds and can be stored for long periods without losing their nutritional value, allowing for flexibility and increased food availability between harvests. Since they can be used for self-consumption or as cash crops, farmers who cultivate pulses have the option to both eat and/or sell their harvest. Additionally, some pulses like pigeon peas and Bambara beans can be cultivated in very poor soils and semi-arid environments where other crops cannot be grown. Crop residues from grain legumes can also be potentially used as animal fodder, and the heightened protein concentration from these residues improves animal health. However, there is minimal quantitative data on the relationship between pulses and food security—further research is needed to show the full potential of pulses in improving food security.

An important attribute of pulses is their ability to biologically fix nitrogen. These plants, in symbiosis with certain types of bacteria (e.g. Rhizobium, Bradyrhizobium), are able to convert atmospheric nitrogen into nitrogen compounds that can be used by growing plants, consequently improving soil fertility.^[1] It has been estimated that legumes can fix between 72 and 350 kg of nitrogen per ha per year.^[2] Additionally, some species of pulses are able to free soil-bound phosphorous, which also plays an important role in the nutrition of plants.^[3] These two features are particularly important for low-input agricultural production systems and agro-ecological principles because it allows to drastically reduce the use fertilizers. At the same time, rotations including leguminous crops allow to continue future production on the same plot of land, pulses in intercropping systems not only allow a higher underground utilization efficiency due to their root structures but also can reduce pesticide utilization and deep rooting pulses like pigeon peas can supply groundwater to intercropped companion species. The use of indigenous pulses like bambara beans might contribute to improve food security because they are adapted to local production and consumption systems. Finally, it is important to note that pulses are highly versatile and can be used in different agricultural production systems like rotations, intercropping, ley-farming and of course as a cover crop.^{[4],[5],[6],[7]}

[1] Nulik, J; Dalgliesh, N; Cox, K.; and Gabb, S. 2013. Integrating herbaceous legumes into crop and livestock systems in eastern Indonesia. Australian Centre for International Agricultural Research (ACIAR), Canberra, Australia.
[2] Frame, J. 2005. Forage legumes for temperate grasslands. Science Publishers, Inc., Enfield, USA and Food and Agriculture Organization of the United Nations, Rome, Italy.
^[3] Rose, TJ; Hardiputra, B; Rengel, Z. 2010. Wheat, canola and grain legume access to soil phosphorus fractions differs in soils with contrasting phosphorus dynamics. Plant and Soil 326: 159–170.
[4] Li, L; Sun, J; Zhang, F; Guo, T; Bao, X; Smith, FA; Smith, SE. 2006. Root distribution and interactions between intercropped species. Ecosystem Ecology 147:280–290.
[5] Hauggaard-Nielsen, H; Jørnsgaard, B;Kinane, J; Jensen, RS. 2008. Grain legume-cereal intercropping: The practical application of diversity, competition and facilitation in arable and organic cropping systems. Renewable Agriculture and Food Systems 23:3–12.
[6] Sekiya, N; Yano, K. 2004. Do pigeon pea and sesbania supply groundwater to intercropped maize through hydraulic lift? – Hydrogen stable isotope investigation of xylem waters. Field Crop Research 86:167–173.
[7] Williams, JT. 1993. Pulses and Vegetables. Underutilized Crop Series. Chapman & Hall, London, England.

Additionally to their nitrogen-fixing and phosphorous-freeing properties, like other leguminous crops, pulses help increase organic matter and microbial biomass and activity (e.g. bacteria, fungi) in the soil. They can also improve soil structure and water retention capacity while helping to reduce wind and water erosion.^[1],[2]

[1] http://www.agriculture.gov.sk.ca/Default.aspx?DN=4b50acd7-fb26-49a9-a31c-829f38598d7e
[2] Biederbeck, VO; Zentner, RP; Campbell, CA. 2005. Soil microbial populations and activities as influenced by legume green fallow in a semiarid climate. Soil Biology and Biochemetry 37:1775–1784.

Pulse species have a broad genetic diversity from which improved varieties can be selected and/or bred—an attribute that is particularly important for adapting to climate change because more climate-resilient varieties can be developed out of this broad diversity. For example, scientists of the International Center for Tropical Agriculture (CIAT) are currently working on the development of pulses which should be able to grow at temperatures above the crop’s normal “comfort zone”. Since climate experts suggested that heat stress will be the biggest threat to bean production in the coming decades, these improved pulse varieties will be of critical importance, especially for low-input agricultural production systems.^[1]

Pulses help mitigate climate change by reducing dependency on synthetic fertilizers. The manufacture of these fertilizers is energy intensive and emits greenhouse gases into the atmosphere, thus their overuse is detrimental to the environment. Many pulses often promote higher rates of accumulation of soil carbon than cereals or grasses.^[2]

[1] Russel, N. 2015. Beans that can beat the heat. International Center for Tropical Agriculture (CIAT), Cali, Colombia.
[2] Jensen, ES; Peoples, MB; Boddey, RM; Gresshoff, PM; Hauggaard-Nielsen, H; Alves, BJR; Morrison MJ. 2012. Legumes for mitigation of climate change and the provision of feedstock for biofuels and biorefineries. A review. Agronomy for Sustainable Development 32:329–364.

In addition to offering a shelf-stable supply of food, pulses crops can provide additional income to producers by being sold and traded. Pulses are high-value crops, usually getting 2-3 times higher prices than cereals.^[1] Local processing of pulses can also offer further employment opportunities in rural areas.

[1] http://grainlegumes.cgiar.org/why-grain-legumes-matter/reducing-rural-poverty/

As of 2013, India is the world’s largest importer of pulses, and Canada is the largest exporter. Official forecasts indicate that Canada will continue as the world’s leading exporter in 2014, exporting 6.2 million tonnes of pulses (primarily peas), followed by Australia (1.7 million tonnes), Myanmar (1.2 million tonnes), United States (1.1 million tonnes) and China (800 000 tonnes), with India being a primary destination for each. India represents more than one-fourth of the world total pulses imports, followed by the European Union, China, Pakistan and Egypt.

Pulse production is highly concentrated. India, where pulses are an important source of protein for a largely vegetarian population, is the world largest producer of pulses, accounting for a quarter of world production in 2013. Together, the top five producing countries accounted for 51 percent of world production in 2013. Nonetheless, the countries occupying the top five spots have shifted significantly over the past 20 years. While India has maintained its status over time, the next four countries are all different to what they were in 1992.

However the consumption of pulses, in per capita terms, has seen a slow but steady decline in both developed and developing countries, dropping from 7.6Kg/person/year in 1970, to 6.1Kg/person/year in 2006. The Near East/North Africa region is the only region where per capita consumption of pulses has increased, rising from 6.2kg/person/year to 7.1kg/person/year over the same time period. According to FAO, these trends reflect not just changing dietary patterns and consumer preferences but also the failure of domestic production to keep pace with population growth in many countries.

Overall, international trade in pulses has grown rapidly, much faster than output.  For instance, a 3.3% annual growth rate between 1990 and 2012 has meant that total exports of pulses have more than doubled, expanding from 6.6 to 13.4 million tons. As a result, the proportion of pulse production that gets traded increased from 11 percent to 18 percent during this period. The value of pulse exports has grown even more rapidly, especially in recent years, rising from US$ 2.5 billion in 1990 to about US$ 9.5 billion in 2012.

For the future, international trade in pulses is likely to continue growing. Constraints to pulse production and productivity growth in the developing regions may not be easily overcome and, as a result, production would most likely lag behind demand. It is expected that many developing countries would continue to rely on imports to meet their needs in pulses.