Journal article

Publication year: 2003

Pages: 14-22

Journal: Journal of Plant Nutrition and Soil Science

Volume number: 166

Issue number: 1

ISSN: 1436-8730

DOI Link: https://doi.org/10.1002/jpln.200390007

Publisher: Wiley-VCH Verlag

Abstract: 
With a world-wide occurrence on about 560 million hectares, sodic soils are characterized by the occurrence of excess sodium (Na+) to levels that can adversely affect crop growth and yield. Amelioration of such soils needs a source of calcium (Ca2+) to replace excess Na+ from the cation exchange sites. In addition, adequate levels of Ca2+ in ameliorated soils play a vital role in improving the structural and functional integrity of plant cell walls and membranes. As a low-cost and environmentally feasible strategy, phytoremediation of sodic soils - a plant-based amelioration - has gained increasing interest among scientists and farmers in recent years. Enhanced CO2 partial pressure (PCO2) in the root zone is considered as the principal mechanism contributing to phytoremediation of sodic soils. Aqueous CO2 produces protons (H+) and bicarbonate (HCO3-). In a subsequent reaction, H+ reacts with native soil calcite (CaCO) to provide Ca2+ for Na+-Ca2+ exchange at the cation exchange sites. Another source of H+ may occur in such soils if cropped with N-2-fixing plant species because plants capable of fixing N-2 release H+ in the root zone. In a lysimeter experiment on a calcareous sodic soil (pH(s) = 7.4, electrical conductivity of soil saturated paste extract (EC6) = 3.1 dS m(-1), sodium adsorption ratio (SAR) = 28.4, exchangeable sodium percentage (ESP) = 27.6, CaCO3 = 50 g kg(-1)), we investigated the phytoremediation ability of alfalfa (Medicago sativa L.). There were two cropped treatments: Alfalfa relying on N-2 fixation and alfalfa receiving NH4NO3 as mineral N source, respectively. Other treatments were non-cropped, including a control (without an amendment or crop), and soil application of gypsum or sulfuric acid. After two months of cropping, all lysimeters were leached by maintaining a water content at 130% water-holding capacity of the soil after every 24 1 h. The treatment efficiency for Na+ removal in drainage water was in the order: sulfuric acid > gypsum = N-2-fixing alfalfa > NH4NO3-fed alfalfa > control. Both the alfalfa treatments produced statistically similar root and shoot biomass. We attribute better Na+ removal by the N-2-fixing alfalfa treatment to an additional source of H+ in the rhizosphere, which helped to dissolve additional CaCO3 and soil sodicity amelioration.

Harvard Citation style: Qadir, M., Steffens, D., Yan, F. and Schubert, S. (2003) Proton release by N-2-fixing plant roots: A possible contribution to phytoremediation of calcareous sodic soils, Journal of Plant Nutrition and Soil Science = Zeitschrift für Pflanzenernährung und Bodenkunde, 166(1), pp. 14-22. https://doi.org/10.1002/jpln.200390007

APA Citation style: Qadir, M., Steffens, D., Yan, F., & Schubert, S. (2003). Proton release by N-2-fixing plant roots: A possible contribution to phytoremediation of calcareous sodic soils. Journal of Plant Nutrition and Soil Science = Zeitschrift für Pflanzenernährung und Bodenkunde. 166(1), 14-22. https://doi.org/10.1002/jpln.200390007