Biological nitrogen fixation of Teline linifolia (L.) Webb & Berth: Soil depth and tree canopy cover effects in the Mâamora cork tree forest (Morocco)

Abstract

Biological nitrogen fixation of Teline linifolia (L.) Webb & Berth: Soil depth and tree canopy cover effects in the Maamora cork tree forest (Morocco) Teline linifolia (L.) Webb & Berth is a multipurpose shrub of the Maamora cork tree forest (Morocco), which illustrates the potential value of legume shrubs in biological nitrogen fixation, soil protection, supply of forage resources during the autumn to winter transition, the activities of winter honeydew bee gathering and the production of firewood. In a pot experiment, the N fixation rate of Teline plants growing on a poor sandy soil (0.09 N%) was linked with N% content (N-15 dilution technique with Teline not inoculated and Dactylis glomerata as controls) in a linear regression: N fixation rate % = 9.52 (N%) + 32.3 with r(2) = 0.706; n = 14. Published data on soja crops from Hawaii, Benin, Brazil, and Switzerland gave accordance to this relationship. Applied in the cork tree forest to N content of annual increment of Teline, it made it possible to calculate mean N fixation rate as 50.8 +/- 2.5%. Mean annual total N fixation was 41 +/- 7 kg/ha. The optimal N fixation, 95 kg/ha, was obtained with 1 to 2 m soil depth combined with a 30 to 75% cork tree canopy cover.