Resumo

VAZQUEZ, M; MILLAN, G  e  GELATI, P. Simulated effect of complementary irrigation on a Typic Udipsamment soil. Cienc. suelo [online]. 2008, vol.26, n.2, pp.195-203. ISSN 1850-2067.

The massive adoption of new farming technologies in the Pampas region has been accompanied by the incorporation of complementary irrigation. The recent adoption of this practice in some areas of the region prevents the evaluation of its medium to long-term impact. Experiments under controlled conditions could contribute to predictive assessments that will help avoid future damages. The proposed hypothesis of this study is that the complementary irrigation by aspersion used in a Typic Udipsamment soil of Central-E Buenos Aires province, causes an increase in soil sodicity and salinity, reaching in the medium term a new situation of stability, if the practice stays within certain parameters (type of water, volume and regularity of the irrigation). The aim of this work was to evaluate the alteration of the composition and ionic relations in the soil solution caused by the prolonged use of complementary irrigation by aspersion, verifying the possibility of reaching another equilibrium state in the medium term. The experimental units were pots of 1.5 L, containing soil sampled at a 0-20 cm depth, simulating 0, 10, 15 and 20 years of irrigation, maintained at 60 ºC and respecting the hidrologic balance of the area. The saline contribution was calculated to be 461.4 kg 100 mm^-1 of irrigation water. The cationic and anionic composition of the latter revealed the predominance of Na⁺ as well as of CO₃ ^2-/CO₃H^-. The most affected edaphic chemical variables were pH, Na⁺, CO₃H^- and SAR. After 10 years of irrigation, both the Na⁺ and the SAR increased more than 10-fold, confirming the hypothesis of new equilibrium states only after 15 years of irrigation. The salinity evaluated through EC slightly increased and subsequently stabilized after 10 years of irrigation, reaching values that did not differ significantly from the original ones. Sodicity surpassed acceptable thresholds and therefore we can assert that, under the experimental conditions of this study, the irrigation practice in Central-E Buenos Aires Province is not sustainable in the long term.

Palavras-chave : Sodicity; Salinity; Water quality; Sustainability.

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