Short communication. Nitrogen content of residual alfalfa taproots under irrigation

S. Cela, F. Santiveri, J. Lloveras


The decomposition of alfalfa (Medicago sativa L.) residues can provide significant amounts of N to subsequent crops, but most of the data on this subject has been obtained from 1-2 year old alfalfa stands. The objective of this study was to determine the biomass of alfalfa taproots and their N content in irrigated alfalfa stands that are more than 2 years old. Twenty-two commercial irrigated alfalfa fields were evaluated in the Ebro Valley (Northeast Spain) from 2006 to 2010. The taproot biomass in the arable layer (0 to 30 cm depth) ranged from 1.8 to 10.1 Mg ha-1 and averaged 4.8 Mg ha-1. In contrast, the N concentration in alfalfa taproots was constant among fields and averaged 24.6 g N kg-1. The total amount of N contained in alfalfa taproots (0-30 cm depth) ranged from 47 to 96 kg N ha-1 in 55% of the fields, ranged from 97 to 200 kg N ha-1 in 22% of the fields, and exceeded 200 kg N ha-1 in 23% of the fields. The N content of the irrigated alfalfa taproots studied here is in the upper range previously reported in other areas, mainly with younger alfalfa stands. Based on the current finding, a classification of the quality of irrigated alfalfa stands is proposed to improve the estimates of the residual-N effects of alfalfa on subsequent crops.


root biomass; alfalfa stands

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Abdul-Jabbar AS, Sammis TW, Lugg DG, 1982. Effect of moisture level on the root pattern of alfalfa. Irrig Sci 3: 197-207. 

Bruuslema TW, Christie BR, 1987. Nitrogen contribution to succeeding corn from alfalfa and red clover. Agron J 79: 96-100. 

Cela S, Salmeron M, Isla R, Cavero J, Santiveri F, Lloveras J, 2011. Reduced nitrogen fertilization to corn following alfalfa in an irrigated semiarid environment. Agron J 103: 520-528. 

Delgado I, Mu-oz-Pérez F, Andueza-Urra D, 2005. El cultivo de la alfalfa en Aragón. Recientes ensayos sobre variedades. Inf Tec 157: 1-16. 

Fox RH, Piekielek WP, 1988. Fertilizer N equivalence of alfalfa, birdsfoot trefoil, and red clover for succeeding corn crops. J Prod Agric 1: 313-317. 

Hakl J, Šantrůček J, Kocourková D, Fuksa P, 2007. The effect of the soil compaction on the contents of alfalfa root reserve nutrients in relation to the stand density and the amount of root biomass. Soil Water Res 2: 54–58. 

Heichel GH, Barnes DK, Vance CP, Henjum KI, 1984. N2 fixation and N and dry matter partitioning during a 4-year alfalfa stand. Crop Sci 24: 811-815. 

Justes E, Thiebeau P, Cattin G, Larbre D, Nicolardot B, 2001. Libération d'azote après retournement de luzerne: un effet sur deux campagnes. Perspect Agric 264: 22-25. 

Kelner DJ, Vessey JK, Entz MH, 1997. The nitrogen dynamics of 1-, 2- and 3-year stands of alfalfa in a cropping system. Agric Ecosyst Environ 64: 1-10. 

Lamba PS, Ahlgren HL, Muckenhirn RJ, 1949. Root growth of alfalfa, medium red clover, bromegrass, and timothy under various soil conditions. Agron J 41: 451-458. 

Lloveras J, Chocarro C, Freixes O, Arqué O, Moreno E, Santiveri F, 2008. Yield, yield components, and forage quality of alfalfa as affected by seeding rate in Mediterranean irrigated conditions. Agron J 100: 191-197. 

Morris TF, Blackmer AM, El-Hout NM, 1993. Optimal rates of nitrogen fertilization for first-year corn after alfalfa. J Prod Agric 6: 344-350. 

Pettersson R, Hansson AC, Andrén O, Steen E, 1986. Above- and below-ground production and nitrogen uptake in lucerne (Medicago sativa). Swed J Agric Res 16: 167-177. 

Upchurch RP, Lovvorn RL, 1951. Gross morphological root habits of alfalfa in North Carolina. Agron J 43: 493-498. 

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DOI: 10.5424/sjar/2013112-3689