Resumen

FLORIO, EVA LAURA; MERCAU, JORGE LUIS  y  NOSETTO, MARCELO DANIEL. FACTORES QUE REGULAN LA DINÁMICA FREÁTICA EN DOS AMBIENTES DE LA PAMPA INTERIOR CON DISTINTOS REGÍMENES DE HUMEDAD. Cienc. suelo [online]. 2015, vol.33, n.2. ISSN 1850-2067.

In most of the Argentinean Pampas, the water-table strongly affects the agricultural systems both positively and negatively. Thus, it is critical to understand the dynamic and drivers of water-table levels in order to make predictions and to design management strategies. In this work, we evaluated the influence of climatic conditions, topography and crop type on the water-table dynamic, at the annual and monthly scales, at two sites in the Inland Pampa with different edaphic/climatic conditions (Pehuajó, Bs. As and Mackenna, Córdoba). For this purpose, we registered the water-table depth periodically during five growing seasons, in 34 boreholes located under different crops (corn, soybean, wheat/soybean and cover crop/corn) and in different topographic positions (lowland, mid-slope, highland). We found that in both sites, climate played a major role on the water-table dynamic, being 80% of the sum of squares (SS) type I explained by the "year" effect (p<0.01). Annual rainfall was linearly related to water-table level changes at both sites (r²=0.37 and 0,56 for Pehuajó and Mackenna, respectively). Crop influence was observed at the monthly scale in Pehuajó, but in Mackenna it was also evidenced at the annual scale, explaining 10% of the SS type I (p<0.01). At this site, we found a close lineal negative relationship between water-table level changes and crop evapotranspiration (r²=0.57), observing deeper water-table levels under double crops. Topography only affected the water-table dynamic in Mackenna and at the monthly scale, when we observed higher water-table rises and drops in lowlands. Although climate was the main driver of the water-table dynamic, crop influence in Mackenna at the annual scale opens the possibility for an agricultural "management" of groundwater levels. The lack of this effect in Pehuajó suggests that soil evaporation may be playing a key role in the hydrological balance.

Palabras clave : Water-table, water balance, topography, evapotranspiration.

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