_ Medicago sativa L.
(Alfalfa)
“Queen of the forage crops,” Medicago sativa L. or otherwise known as alfalfa, is one of the most productive legumes in our country. Alfalfa is the fourth most widely grown crop in the United States. (Martin 1976) In many states, alfalfa is easily the most productive crop. Alfalfa is considered an excellent forage that is extremely high in quality with many uses around the United States. It is also recognized for being a very well known crop as well as a popular crop to many farmers. Alfalfa is a multi use legume that is a key component to agricultural systems today.
CROP DESPCRIPTION- Origin & Adaption
Alfalfa first originated in central Asia, an arid region were insufficient water is the chief limiting factor in plant growth. California, South Dakota, and Wisconsin are the three main states for production in the United States. (AIM Committee 1996) Worldwide the center of production consists of Canada, Argentina, Southern Europe, Australia, South Africa, and the Middle East. Alfalfa requires a pH of 6.5 or higher to be properly maintained. (NDSU 1992) High soil fertility is necessary with alfalfa including proper drainage. In order for alfalfa to adapt correctly, the soil must have a constant supply of calcium, magnesium, potassium, and boron. (Natural Blues 2008)
Appearance
Alfalfa has leaves that are an abovate form. They are alternately arranged on the stem and are normally in a trifoliate leaf shape. The leaf margins appear serrated while the leaf is attached to the stem in a petiole way. Alfalfa has an erect growth pattern. (Natural Blues 2008) The stem is moderately strong, woody, and high in fiber. The plant grows upward to about 2 to 3 feet tall standing alone. Alfalfa is generally referred to growing in a brush form. The flower produced from this plant is a typical legume flower. (Natural Blues 2008) The flower forms a loose cluster and varies in color from purple to yellow. The flower has five petals, one standard, two wings, and two fused together to form a keel. Alfalfa produces a dehiscent fruit or a pod. In each pod, there are several small kidney shaped seeds. These seeds are considered dicot seeds because they consist of two cotyledons. Alfalfa has a primary root system. (Natural Blues 2008) This consists of a large central axis and several small lateral roots. Alfalfas roots are in the taproots system. The taproot is known for penetrating deep into the soil, which is a major importance for alfalfa, especially in states that often have a drought. (Lancaster 2010)
Classification
The scientific classification is much like any other legume. Alfalfa is part of the magnoliopsida class and it is in the Fabales order. (USDA n.d) Alfalfa is a flowering plant in the Fabacea family or the pea family. The genus is Medicago L. while the species is Medicago sativa L. The symbol for alfalfa is MESA. (USDA n.d)
POPULARITY & PROGRESSION- Hay Trade
The Oklahoma hay trade is a continually fluctuating industry. The 2011 hay trade was considered low to moderate because of the drought. However, there is demand for good quality hay in the dairy and horse industry. The unavailability of alfalfa this year lead to out of state purchasing. (USDA n.d) This unfortunately caused alfalfa prices to raise in addition to the already high transportation costs.
Growing Interest
Alfalfa has been growing in its popularity for many years due to the extensive list of uses it has. Alfalfa can most commonly be made into hay or silage for livestock and equine. It is becoming a common addition to some meals for humans. Alfalfa has always been forage grazed on by animals. The most surprising use for alfalfa is the medical uses. (Acquaah 2005) Alfalfa is also a popular rotation crop because it does not require the use of nitrogen fertilizer. The high biomass production of alfalfa is another importance. The record yield of one acre is 10 tons/acre without irrigation. With irrigation, the record yield is 24 tons/acre. (Martin Leonard, and Stamp 2006)
BIOLOGY- Lifecycle
Alfalfa is a long-lived perennial that has the capability of thriving for more than five years under the right conditions. The plant is typically planted in late August into September. If alfalfa is planted to late into the season, this does not allow adequate time for the seed to produce roots before the cold temperatures. (Martin, Leonard, and Stamp 2006) During the first week of life, under the ideal conditions, alfalfa germinates. It grows a taproot before sending the cotyledons up through the soil. Within the next 45 days a crown of stems and leaves forms. This crown will thicken and expand well into its fourth year of life. (Martin et. al. 2006) A common rule in alfalfa is the plants must have five leaves before the first hard freeze to ensure a good chance of survival.
Nitrogen
Alfalfa as a crop is widely known for its biological nitrogen fixation abilities. Many crops remove nitrogen from the soil making alfalfa a very beneficial rotation crop. The average acre of alfalfa will fix about 200 kg of nitrogen per year. (NDSU 2008) In order for nitrogen fixation to take place the legume, in this case alfalfa must be harboring the nitrogen-fixing bacteria. Both the bacteria and the alfalfa can survive independently but only together, are they capable of improving the soil’s nitrogen levels. (NDSU 2008) This reduces the need to apply expensive nitrogen fertilizers.
HISTORY- United States
Alfalfa was first originated in central Asia, from there it has been taken all over the world in order to find places it could have the most importance. Alfalfa has established itself as not only one of the most important forage crops, but one of the most important leguminous forage crops. The name alfalfa is of Arabic origin and means the best fodder. It is dated; in 1854, alfalfa was first brought to what is now San Francisco from Chile. (White 1949) Alfalfa continued to move east through the decades. Where the production was successful, the crop stuck. For example, the Great Plains found humidity was a helpful additive when growing alfalfa. As alfalfa moved eastward, it found the soil conditions were less favorable. (White 1949) As we learn more about this crop and the places it is highest yielding, we are more capable of designing new varieties for different climates.
Oklahoma
Oklahoma was behind however when it came to finding alfalfa. Alfalfa was first brought into the Oklahoma territory just before the 1900’s. When alfalfa was first being grown, no other crops had been planted in Oklahoma. (AIM Committee 1996) This meant the soils were high in fertility yet low in acidic content. In the beginning alfalfa did very well, it had no enemies yet in Oklahoma and it was yielding fairly well. Due to the lack of knowledge, alfalfa was planted repeatedly. (Orloff, Carlson, and Teuber 1989) This would result in lack of fertility in the soil. Since that time, it has been learned alfalfa will always struggle because of the high temperatures and low rainfall counts.
LIVESTOCK USES
Over many decades, alfalfa has been made useful for an array of different tasks, animals, and products. As early, as the medieval times alfalfas main purpose was for homes. Alfalfa was used as fodder when building many people’s homes. (White 1949) The uses of this crop have drastically changed over the years. In livestock and equine alfalfa, hay is an incredibly desirable forage. Alfalfa is the high nutritional value in addition to it already being a good digestible fiber. Alfalfa contains about 15 to 22% crude protein. (Vertroni, Volenec, and Cangiano 2010) It is also an excellent source of vitamins and minerals. As well as alfalfa being fed as hay, it can be fed as silage or grazed. Alfalfa has surprisingly become a popular addition to human diets.
MEDICAL USES
Not only have we found ways to use alfalfa as a food for humans, but also we have found beneficial medical uses for it. The alfalfa sprouts have been a popular addition to salads, soups and sandwiches. People have found nourishment in extracting the juice from the leaves also. Tea can be made from the seeds and the dried leaves of the alfalfa plant by boiling and straining them. The greatest healing power of alfalfa is however improving ones digestive system and ensuring better assimilation of food. (Natural Blues 2008) The seeds, leaves and stems are all used in ways to help various issues. Heart disorders, hair disorders and respiratory disorders may be relieved by drinking the juice from alfalfa. (Natural Blues 2008) The seeds may be used to create tea to help sooth stomach disorders as well as arthritis. The herb obtained from alfalfa is often used as an effective remedy for high blood pressure. It contains necessary elements for softening hardened arteries, which is a characteristic of high blood pressure. (Natural Blues 2008)
AGRONOMIC USES
As an agronomic use, alfalfa is considered a cash crop. To some people alfalfa is viewed as a top cash crop because of its high marketability. Regardless of the region in the country, most livestock are fed some type of forage. This results in there being a constant demand for alfalfa hay in many parts of the country. The demand may be larger in some states than other depending on the yields and availability of the crop. (Natural Blues 2008) In addition to having agronomic uses, alfalfa also has some industrial uses. Alfalfa is often used for health supplements and dietary foods. Many of the health supplements are driven towards living a happy healthy life. The dietary foods are much like the ordinary foods people consume from alfalfa. Most products made from alfalfa have a high dietary value as well as being very healthy for the human body.
PRODUCTION CYCLE
The production cycle of alfalfa varies from state to state. Alfalfa grows best in temperate to subtropical climates. High yields result from warm climate and moderate rainfall. (Acquaah 2005) Most commonly, alfalfa can be established successfully in either spring or fall. In Oklahoma, alfalfa is generally planted between late August and early September, while Arkansas plants between September and mid October. Alfalfa grows best in soils with a pH around 6.5 and 7.5. (Acquaah 2005) Planting depth for alfalfa should be anywhere from ¼ inch to ½ inch. When planting alfalfa many people prefer drill planting opposed to broadcast spreading. Drill planting places the seed at a uniform depth, which improves seedling emergence. Recommending seeding rates for alfalfa range from 15 to 20 pounds an acre. (Acquaah 2005) Research has shown higher yields are obtained by applying more seed.
As well as planting alfalfa, the date at which alfalfa is harvested varies on geographical location. Alfalfa is a crop that can harvested multiple times during the warm months. In the Midwest, alfalfa is harvested for hay about three to four times a year. Alfalfa is harvested when it is just above one foot of height and right before the plant blooms. (Martin et. al. 2006) When the alfalfa hay is ready to be harvested, it will first be cut low to the ground. It is then dried and raked and then it continues to dry. Once the alfalfa is dried properly, the hay can safely be baled without worry of mold growth.
WORLDWIDE PRODUCTION
In 2006, the worldwide production of alfalfa was near 430 million tons. (Vertroni et. al. 2010) Alfalfa has been named the most cultivated forage crop of the world. The United States is the largest producer of alfalfa in the world, just ahead of Canada and Australia. California, South Dakota, and Wisconsin are among the leading production states in the United States. Records show the Midwest is responsible for about 50% of the whole US production. The northeast accounts for about 10%; the western states about 40% and the south with little to none. (USDA n.d)
ALFALFA & INSECTS
Alfalfa, much like other crops requires the presence of a pollinator. In most cases, western honeybees are a popular pollinator, except when it comes to alfalfa. Often the pollen-carrying keel of the alfalfa flower trips and strikes pollinating bees on the head. (Orloff et. al. 1989) However, the western honeybees do not enjoy being repeatedly hit on the head. The bees have learned to draw the nectar from the side of the flower but in this case, the bees are unable come in contact with the pollen and further transfer it. (Orloff et. al. 1989) Because of this common problem, the alfalfa leave cutter bee is becoming more popular in alfalfa pollination.
MAJOR DISEASE & PROBLEMS
Alfalfa disease maybe the result of interactions between susceptible cultivars, pathogens, and occasionally from improper management practices. Unfortunately, more than one disease normally strikes an alfalfa plant. Common leaf spot is a general disease in alfalfa. It results in small brown spots, drooping leaves, and more importantly up to 40 % yield loss. (Acquaah 2005) Bacterial wilt is a frequent disease during harvesting. Signs of an effected plant are, yellow-green leaves, stunted growth, and deformed leaf heads. (Acquaah 2005) It is becoming more known for alfalfa to be less tolerant against diseases.
Alfalfa has become a widely important forage legume throughout the United States. The uses of alfalfa range in all directions, from livestock use to medical use. Alfalfa can successfully be named the “The queen of forage crops.” I believe the uses from alfalfa will continue to emerge and this crop will continue to grow in importance as well as popularity.
References
Acquaah, George. 2005. Principles of Crop Production. Pearson Education Inc., New Jersey.
AIM Committee. 1996. Alfalfa Stand Establishment- Questions and answers. Available at http://www.alfalfa.okstate.edu/pub/stand-949/stand-est.htm#contributor (Assessed 19 Oct. 2011) Oklahoma State University, Stillwater, OK.
Lancaster, S., 2010. Introduction to Plant and Soil Sciences. Pearson Learning Solutions. Boston, MA.
Martin, J.H., Leonard W.H. and Stamp D.L. 1976. Principles of Field Crop Production. Prentice-Hall, Inc., New Jersey.
Natural Blues. 2008. Medicago Sativa- Alfalfa. Available at http://bioweb.uwlax.edu/bio203/s2008/brooks_kels/ (Assessed 12 Sept 2011). Natural Blues.
NDSU. 1992. Fertilizing alfalfa. Article Available at http://www.ag.ndsu.edu/pubs/planti/soilfert/sf728w.htm (accessed 1 October 2011). NDSU-EO/AA University. North Dakota.
Orloff, S.B., Carlson H.L. and Teuber, L.R. 1989. Intermountain Alfalfa Management. University of California. Oakland, California.
USDA-Natural Resource Conservation Service-National Plant Data Team. Plant database. Available at http://plant.usda.gov/java/profile?symbol=MESA (Assessed 12 Sept 2011). USDA-NRCS.
Vertroni, L., Volenec, J. and Cangiano, C. 2010. Fall Dormancy and Cutting Frequency Impact on Alfalfa. Field Crop Research. Article Available at http://www.sciencedirect.com.argo.library.okstate.edu/science/article/pii/S0378429010001954 (Assessed 19 Oct. 2011)
White, J. William. 1949. Alfalfa Improvement. Advances in Agronomy. Acedimic Press Inc.
“Queen of the forage crops,” Medicago sativa L. or otherwise known as alfalfa, is one of the most productive legumes in our country. Alfalfa is the fourth most widely grown crop in the United States. (Martin 1976) In many states, alfalfa is easily the most productive crop. Alfalfa is considered an excellent forage that is extremely high in quality with many uses around the United States. It is also recognized for being a very well known crop as well as a popular crop to many farmers. Alfalfa is a multi use legume that is a key component to agricultural systems today.
CROP DESPCRIPTION- Origin & Adaption
Alfalfa first originated in central Asia, an arid region were insufficient water is the chief limiting factor in plant growth. California, South Dakota, and Wisconsin are the three main states for production in the United States. (AIM Committee 1996) Worldwide the center of production consists of Canada, Argentina, Southern Europe, Australia, South Africa, and the Middle East. Alfalfa requires a pH of 6.5 or higher to be properly maintained. (NDSU 1992) High soil fertility is necessary with alfalfa including proper drainage. In order for alfalfa to adapt correctly, the soil must have a constant supply of calcium, magnesium, potassium, and boron. (Natural Blues 2008)
Appearance
Alfalfa has leaves that are an abovate form. They are alternately arranged on the stem and are normally in a trifoliate leaf shape. The leaf margins appear serrated while the leaf is attached to the stem in a petiole way. Alfalfa has an erect growth pattern. (Natural Blues 2008) The stem is moderately strong, woody, and high in fiber. The plant grows upward to about 2 to 3 feet tall standing alone. Alfalfa is generally referred to growing in a brush form. The flower produced from this plant is a typical legume flower. (Natural Blues 2008) The flower forms a loose cluster and varies in color from purple to yellow. The flower has five petals, one standard, two wings, and two fused together to form a keel. Alfalfa produces a dehiscent fruit or a pod. In each pod, there are several small kidney shaped seeds. These seeds are considered dicot seeds because they consist of two cotyledons. Alfalfa has a primary root system. (Natural Blues 2008) This consists of a large central axis and several small lateral roots. Alfalfas roots are in the taproots system. The taproot is known for penetrating deep into the soil, which is a major importance for alfalfa, especially in states that often have a drought. (Lancaster 2010)
Classification
The scientific classification is much like any other legume. Alfalfa is part of the magnoliopsida class and it is in the Fabales order. (USDA n.d) Alfalfa is a flowering plant in the Fabacea family or the pea family. The genus is Medicago L. while the species is Medicago sativa L. The symbol for alfalfa is MESA. (USDA n.d)
POPULARITY & PROGRESSION- Hay Trade
The Oklahoma hay trade is a continually fluctuating industry. The 2011 hay trade was considered low to moderate because of the drought. However, there is demand for good quality hay in the dairy and horse industry. The unavailability of alfalfa this year lead to out of state purchasing. (USDA n.d) This unfortunately caused alfalfa prices to raise in addition to the already high transportation costs.
Growing Interest
Alfalfa has been growing in its popularity for many years due to the extensive list of uses it has. Alfalfa can most commonly be made into hay or silage for livestock and equine. It is becoming a common addition to some meals for humans. Alfalfa has always been forage grazed on by animals. The most surprising use for alfalfa is the medical uses. (Acquaah 2005) Alfalfa is also a popular rotation crop because it does not require the use of nitrogen fertilizer. The high biomass production of alfalfa is another importance. The record yield of one acre is 10 tons/acre without irrigation. With irrigation, the record yield is 24 tons/acre. (Martin Leonard, and Stamp 2006)
BIOLOGY- Lifecycle
Alfalfa is a long-lived perennial that has the capability of thriving for more than five years under the right conditions. The plant is typically planted in late August into September. If alfalfa is planted to late into the season, this does not allow adequate time for the seed to produce roots before the cold temperatures. (Martin, Leonard, and Stamp 2006) During the first week of life, under the ideal conditions, alfalfa germinates. It grows a taproot before sending the cotyledons up through the soil. Within the next 45 days a crown of stems and leaves forms. This crown will thicken and expand well into its fourth year of life. (Martin et. al. 2006) A common rule in alfalfa is the plants must have five leaves before the first hard freeze to ensure a good chance of survival.
Nitrogen
Alfalfa as a crop is widely known for its biological nitrogen fixation abilities. Many crops remove nitrogen from the soil making alfalfa a very beneficial rotation crop. The average acre of alfalfa will fix about 200 kg of nitrogen per year. (NDSU 2008) In order for nitrogen fixation to take place the legume, in this case alfalfa must be harboring the nitrogen-fixing bacteria. Both the bacteria and the alfalfa can survive independently but only together, are they capable of improving the soil’s nitrogen levels. (NDSU 2008) This reduces the need to apply expensive nitrogen fertilizers.
HISTORY- United States
Alfalfa was first originated in central Asia, from there it has been taken all over the world in order to find places it could have the most importance. Alfalfa has established itself as not only one of the most important forage crops, but one of the most important leguminous forage crops. The name alfalfa is of Arabic origin and means the best fodder. It is dated; in 1854, alfalfa was first brought to what is now San Francisco from Chile. (White 1949) Alfalfa continued to move east through the decades. Where the production was successful, the crop stuck. For example, the Great Plains found humidity was a helpful additive when growing alfalfa. As alfalfa moved eastward, it found the soil conditions were less favorable. (White 1949) As we learn more about this crop and the places it is highest yielding, we are more capable of designing new varieties for different climates.
Oklahoma
Oklahoma was behind however when it came to finding alfalfa. Alfalfa was first brought into the Oklahoma territory just before the 1900’s. When alfalfa was first being grown, no other crops had been planted in Oklahoma. (AIM Committee 1996) This meant the soils were high in fertility yet low in acidic content. In the beginning alfalfa did very well, it had no enemies yet in Oklahoma and it was yielding fairly well. Due to the lack of knowledge, alfalfa was planted repeatedly. (Orloff, Carlson, and Teuber 1989) This would result in lack of fertility in the soil. Since that time, it has been learned alfalfa will always struggle because of the high temperatures and low rainfall counts.
LIVESTOCK USES
Over many decades, alfalfa has been made useful for an array of different tasks, animals, and products. As early, as the medieval times alfalfas main purpose was for homes. Alfalfa was used as fodder when building many people’s homes. (White 1949) The uses of this crop have drastically changed over the years. In livestock and equine alfalfa, hay is an incredibly desirable forage. Alfalfa is the high nutritional value in addition to it already being a good digestible fiber. Alfalfa contains about 15 to 22% crude protein. (Vertroni, Volenec, and Cangiano 2010) It is also an excellent source of vitamins and minerals. As well as alfalfa being fed as hay, it can be fed as silage or grazed. Alfalfa has surprisingly become a popular addition to human diets.
MEDICAL USES
Not only have we found ways to use alfalfa as a food for humans, but also we have found beneficial medical uses for it. The alfalfa sprouts have been a popular addition to salads, soups and sandwiches. People have found nourishment in extracting the juice from the leaves also. Tea can be made from the seeds and the dried leaves of the alfalfa plant by boiling and straining them. The greatest healing power of alfalfa is however improving ones digestive system and ensuring better assimilation of food. (Natural Blues 2008) The seeds, leaves and stems are all used in ways to help various issues. Heart disorders, hair disorders and respiratory disorders may be relieved by drinking the juice from alfalfa. (Natural Blues 2008) The seeds may be used to create tea to help sooth stomach disorders as well as arthritis. The herb obtained from alfalfa is often used as an effective remedy for high blood pressure. It contains necessary elements for softening hardened arteries, which is a characteristic of high blood pressure. (Natural Blues 2008)
AGRONOMIC USES
As an agronomic use, alfalfa is considered a cash crop. To some people alfalfa is viewed as a top cash crop because of its high marketability. Regardless of the region in the country, most livestock are fed some type of forage. This results in there being a constant demand for alfalfa hay in many parts of the country. The demand may be larger in some states than other depending on the yields and availability of the crop. (Natural Blues 2008) In addition to having agronomic uses, alfalfa also has some industrial uses. Alfalfa is often used for health supplements and dietary foods. Many of the health supplements are driven towards living a happy healthy life. The dietary foods are much like the ordinary foods people consume from alfalfa. Most products made from alfalfa have a high dietary value as well as being very healthy for the human body.
PRODUCTION CYCLE
The production cycle of alfalfa varies from state to state. Alfalfa grows best in temperate to subtropical climates. High yields result from warm climate and moderate rainfall. (Acquaah 2005) Most commonly, alfalfa can be established successfully in either spring or fall. In Oklahoma, alfalfa is generally planted between late August and early September, while Arkansas plants between September and mid October. Alfalfa grows best in soils with a pH around 6.5 and 7.5. (Acquaah 2005) Planting depth for alfalfa should be anywhere from ¼ inch to ½ inch. When planting alfalfa many people prefer drill planting opposed to broadcast spreading. Drill planting places the seed at a uniform depth, which improves seedling emergence. Recommending seeding rates for alfalfa range from 15 to 20 pounds an acre. (Acquaah 2005) Research has shown higher yields are obtained by applying more seed.
As well as planting alfalfa, the date at which alfalfa is harvested varies on geographical location. Alfalfa is a crop that can harvested multiple times during the warm months. In the Midwest, alfalfa is harvested for hay about three to four times a year. Alfalfa is harvested when it is just above one foot of height and right before the plant blooms. (Martin et. al. 2006) When the alfalfa hay is ready to be harvested, it will first be cut low to the ground. It is then dried and raked and then it continues to dry. Once the alfalfa is dried properly, the hay can safely be baled without worry of mold growth.
WORLDWIDE PRODUCTION
In 2006, the worldwide production of alfalfa was near 430 million tons. (Vertroni et. al. 2010) Alfalfa has been named the most cultivated forage crop of the world. The United States is the largest producer of alfalfa in the world, just ahead of Canada and Australia. California, South Dakota, and Wisconsin are among the leading production states in the United States. Records show the Midwest is responsible for about 50% of the whole US production. The northeast accounts for about 10%; the western states about 40% and the south with little to none. (USDA n.d)
ALFALFA & INSECTS
Alfalfa, much like other crops requires the presence of a pollinator. In most cases, western honeybees are a popular pollinator, except when it comes to alfalfa. Often the pollen-carrying keel of the alfalfa flower trips and strikes pollinating bees on the head. (Orloff et. al. 1989) However, the western honeybees do not enjoy being repeatedly hit on the head. The bees have learned to draw the nectar from the side of the flower but in this case, the bees are unable come in contact with the pollen and further transfer it. (Orloff et. al. 1989) Because of this common problem, the alfalfa leave cutter bee is becoming more popular in alfalfa pollination.
MAJOR DISEASE & PROBLEMS
Alfalfa disease maybe the result of interactions between susceptible cultivars, pathogens, and occasionally from improper management practices. Unfortunately, more than one disease normally strikes an alfalfa plant. Common leaf spot is a general disease in alfalfa. It results in small brown spots, drooping leaves, and more importantly up to 40 % yield loss. (Acquaah 2005) Bacterial wilt is a frequent disease during harvesting. Signs of an effected plant are, yellow-green leaves, stunted growth, and deformed leaf heads. (Acquaah 2005) It is becoming more known for alfalfa to be less tolerant against diseases.
Alfalfa has become a widely important forage legume throughout the United States. The uses of alfalfa range in all directions, from livestock use to medical use. Alfalfa can successfully be named the “The queen of forage crops.” I believe the uses from alfalfa will continue to emerge and this crop will continue to grow in importance as well as popularity.
References
Acquaah, George. 2005. Principles of Crop Production. Pearson Education Inc., New Jersey.
AIM Committee. 1996. Alfalfa Stand Establishment- Questions and answers. Available at http://www.alfalfa.okstate.edu/pub/stand-949/stand-est.htm#contributor (Assessed 19 Oct. 2011) Oklahoma State University, Stillwater, OK.
Lancaster, S., 2010. Introduction to Plant and Soil Sciences. Pearson Learning Solutions. Boston, MA.
Martin, J.H., Leonard W.H. and Stamp D.L. 1976. Principles of Field Crop Production. Prentice-Hall, Inc., New Jersey.
Natural Blues. 2008. Medicago Sativa- Alfalfa. Available at http://bioweb.uwlax.edu/bio203/s2008/brooks_kels/ (Assessed 12 Sept 2011). Natural Blues.
NDSU. 1992. Fertilizing alfalfa. Article Available at http://www.ag.ndsu.edu/pubs/planti/soilfert/sf728w.htm (accessed 1 October 2011). NDSU-EO/AA University. North Dakota.
Orloff, S.B., Carlson H.L. and Teuber, L.R. 1989. Intermountain Alfalfa Management. University of California. Oakland, California.
USDA-Natural Resource Conservation Service-National Plant Data Team. Plant database. Available at http://plant.usda.gov/java/profile?symbol=MESA (Assessed 12 Sept 2011). USDA-NRCS.
Vertroni, L., Volenec, J. and Cangiano, C. 2010. Fall Dormancy and Cutting Frequency Impact on Alfalfa. Field Crop Research. Article Available at http://www.sciencedirect.com.argo.library.okstate.edu/science/article/pii/S0378429010001954 (Assessed 19 Oct. 2011)
White, J. William. 1949. Alfalfa Improvement. Advances in Agronomy. Acedimic Press Inc.