IDL-BNC @ IDRC >
IDRC / CRDI >
IDRC Research Results / Résultats de recherches du CRDI >

Please use this identifier to cite or link to this item: http://hdl.handle.net/10625/49979

Title: Water and nitrate exchange between cultivated ecosystems and groundwater in the Rolling Pampas
Authors: Portela, Silvina I
Andriulo, Adrián E
Jobbagy, Esteban G
Sasal, Maria C
Keywords: WATER TABLE LEVEL
GROUNDWATER HYDROLOGY
EVAPORATIVE DISCHARGE
NITRATE LEACHING
ARGENTINA
RECHARGE-DISCHARGE HYDROLOGICAL BEHAVIOR
HYDROLOGY
Issue Date: 2009
Citation: Portela, S. I., Andriulo, A. E., Jobbagy, E. G., & Sasal, M. C. (2009). Water and nitrate exchange between cultivated ecosystems and groundwater in the Rolling Pampas. Agriculture, Ecosystems and Environment, 134: 277-286. doi:10.1016/j.agee.2009.08.001
Abstract: Understanding nitrogen (N) exchange between cultivated ecosystems and groundwater becomes crucial in the Rolling Pampas where high and variable water table levels are accompanied by increasing N-fertilization rates. Field monitoring of crops, soils and groundwater was combined with modeling to evaluate bidirectional flows (from terrestrial ecosystems to aquifers and vice versa) of water and N throughout a 10-year period (1998–2007) of highly variable precipitation (760–1506 mm year 1) and water table depths (6.5 to <1 m). Piezometers at three topographic positions (upland: UP, mid slope: MS, and toe slope: TS; 1740 and 510 m apart) were used to monitor water table depth and phreatic (<14 m), intermediate (35 m) and bottom of the aquifer (45 m) water chemistry. Crop production and soil water and nitrate content were monitored in two agricultural plots (wheat/soybean–corn rotation) where MS and TS piezometers were located. Nitrate concentration in phreatic groundwater was relatively stable and low at UP and MS (<10 mg l 1) but increased sharply at TS (>45 mg l 1) during periods of high water table levels (<3 m deep). Groundwater chloride concentrations increased with depth in piezometers at UP and MS, but showed the opposite trend at TS during periods of high water table levels, suggesting evaporative discharge at this position. The lateral hydraulic gradient (moving energy) between MS and TS ranged from 0.1 to 0.4% and was negatively correlated with water table depth at TS (R2 = 0.23, p < 0.001, n = 79) indicating that groundwater flow towards TS increased as the water table level rose. A capillary transportmodel (UPFLOW) suggested that at TS groundwater supplied an important amount of water and solutes to crops with corn obtaining approximately half of its water needs (228–413 mm) and one fourth of its N requirement (38–76 kg ha 1) from groundwater. Water and N supply from groundwater may have explained the higher biomass and grain yield in the lower positions of each plot with regard to the rest of the area. Our results suggest that the Rolling Pampas landscapes can switch from a typical recharge behavior to a recharge–discharge one following extended rainy periods that rise water table levels and hydraulic gradients, favoring water and solute transport towards the lower positions of the landscape and local concentration of solutes by groundwater consumption, simultaneously affecting groundwater quality.
URI: http://hdl.handle.net/10625/49979
ISBN: 0167-8809
Project Number: 106299
Project Title: Climate Change and Water Award Program : Adaptation H20
Document Delivery: To enquire about document delivery, contact the IDRC Library : reference@idrc.ca or 613-696-2578 / Pour plus de renseignements sur la livraison de documents, communiquer avec la bibliothèque du CRDI : reference@idrc.ca ou 613-696-2578.
Appears in Collections:IDRC Research Results / Résultats de recherches du CRDI
Research Results (Fellowships and Awards) / Résultats de recherche (Programme de bourses)
Research Results (CCW) / Résultats de recherches (CCE)
2000-2009 / Années 2000-2009
Journal Articles / Articles de revue
All Research Results (IDRC Corporate Awards) / Résultats de recherche (Bourses du CRDI)

Files in This Item:

File Description SizeFormat
IDL-49979.pdf
674.75 kBAdobe PDF
IDRC staff can log in using their network password; non-IDRC staff can request this document.

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

 

Valid XHTML 1.0! DSpace Software Copyright © 2002-2010  Duraspace - Feedback