Fertilization of peanut with selenium

Authors: Sorensen, Ronald - Ron; Nuti, Russell

Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2011
Publication Date: 6/11/2011
Citation: Sorensen, R.B., Nuti, R.C. 2011. Fertilization of Peanut with Selenium. Peanut Science. 38:26-30.

Interpretive Summary: Peanut kernels are a great source of protein and contain a variety of vitamins, minerals, and beneficial unsaturated fats. Human consumption of peanut requires growers to produce the best quality peanut possible to maintain these high standards. Selenium (Se) concentration in the soil depends on the parent material from which soil is derived. The Southeast, where a major portion of peanut is grown, is one of three major areas of the United States where Se concentrations are low (<5 ppm). These low soil concentrations do not necessarily reduce plant growth or reduce crop yield. Conversely, high concentrations of Se have been documented to harm animals when eating vegetation growing on high Se soils and humans who eat both animals and vegetation grown on these soils. Selenium is considered an antioxidant and anti-carcinogenic. Low Se in the human diet may contribute to development of a form of heart disease, hypothyroidism, and weakened immune. Se deficiency was not the cause of the illness but rather, it can make the body more susceptible to an illness caused by other nutritional, biochemical, or infectious stresses. Selenium deficiency in the U.S. is rare but has been seen in other countries, most notably China, where soil concentrations of Se are low. Dietary Reference Intakes developed by the Institute of Medicine recommend that adults need about 55 ppb Se/day. Peanut is typically grown on low Se soils and has about 29 ppb per pound of raw peanut. With peanuts being shipped around the world from the U.S., increasing the level of Se concentration could be beneficial to the dietary needs of developing countries or in areas where nutritional supplements may be less available. The objectives of this research were to determine if adding Se to the soil could increase Se concentration in the peanut plant and examine the economics of Se fertilization. This project was conducted at two sites in Georgia with two soil types and irrigated with subsurface drip irrigation. The experiment was a randomized complete block design with five treatments consisting of an untreated control and four Se concentrations replicated three times. Se rates were 0.5, 1.0, 5.0, and 10 ppm in soil applied after planting but prior to peanut emergence. Sodium selenite (Na2Se03) was dissolved in water and applied on the soil surface. Prior to harvest, plant samples were collected, washed, partitioned, dried, and ground to pass through a sieve and analyzed for Se. Composite soil samples were taken prior to peanut digging, air dried, and analyzed for Se. In general, the higher the concentration of Se applied to the soil the higher the concentration of Se in peanut leaf, stem, root, peg, kernel, and hull. There was no difference in Se concentration between sites for leaf, stem, root, or pegs. There was a difference of Se between sites with hulls and kernels possibly attributed to soil series. Pooled data over both sites showed the untreated areas had an average 0.495 ppm in the kernels. The 0.5Se and 1Se treatment had an average Se concentration of 3.97 ppm in the kernels. These Se levels decreased the quantity of peanuts a person would need to consume from 1.7 pounds per day 0.5 oz/day to get the needed requirement of Se. Adding Se to the soil can increase Se in the peanut kernel and plant which could be beneficial to human and/or animal health. However, adding high grade Se to peanut land at 0.5 ppm would cost about $213/ac which may not be economical for the grower.

Technical Abstract: Increasing Selenium (Se) in the peanut (Arachis hypogaea L.) plant could benefit human and animal health. Selenium is identified as an antioxidant and anti-carcinogenic. In 2006, Se was applied to soil at two locations and four concentrations to determine Se concentration in the peanut plant. Selenium (Sodium Selenite) was applied at rates of 0.5, 1.0, 5.0 and 10 mg Se/kg soil. Prior to harvest, plant samples were collected, washed, partitioned, dried, and ground to pass through a 2 mm sieve and analyzed for Se. Composite soil samples were taken prior to peanut digging, air dried, and analyzed for Se. In general, the higher the concentration of Se applied to the soil the higher the concentration of Se in peanut leaf, stem, root, peg, kernel, and hull. There was no difference in Se concentration between sites for leaf, stem, root, or pegs. There was a difference of Se between sites with hulls and kernels possibly attributed to soil series. Pooled data over both sites showed the untreated areas had an average 0.495 mg Se/kg kernel. The 0.5Se and 1Se treatment had an average Se concentration of 3.97 mg Se/kg kernel. These Se levels decreased the quantity of peanuts a person would need to consume from 760 to 14 g/day to get the needed requirement of Se. The treatments 5Se and 10Se averaged 16.1 mg Se/kg kernel. Adding Se to the soil can increase Se in the peanut kernel and plant which could be beneficial to human and/or animal health. However, adding high grade Se to peanut land at 0.5 mg Se/kg would cost about $526/ha which may not be economical for the grower.