Resumen

GARCIAPRECHAC, Fernando; TERRA, José; SAWCHIK, Jorge  y  PEREZBIDEGAIN, Mario. Improving USLE / RUSLE Estimations Using Runoff Plots Data to Consider the Effect of Soil Water Content. Agrociencia Uruguay [online]. 2017, vol.21, n.2, pp.100-104. ISSN 1510-0839.

Long-term experimental data were obtained in three Argiudolls in runoff plots under natural rainfall in Uruguay: 1) AguasBlancas, 1982-1986, five different Soil Management Systems (SMS), 89 erosive storms, 2) La Estanzuela, 1984-1989, sixSMS, 144 erosive storms, and 3) Palo a Pique, 1994-1999, six SMS, 137 erosive storms; in all sites, it was completed onecycle of the longest rotation. The linear regression between annual soil erosion estimated with USLE/RUSLE and the experimentalone was: EroEst = 0.958EroExp + 1.485, r2 = 0.96, close to 1:1.The highest erosion occurred in the permanently bareand tilled soil SMS, around 40, 50 and 90 Mg.ha-1.yr-1, respectively, when in the other SMS it was below 20 Mg.ha-1.yr-1. Baresoil water content was always close to field capacity due to the extremely low evaporation after the upper few cm of soil are dry.Not considering these three situations, the regression of the remaining 14 SMS situations having full evapotranspiration wasEroEst = 1.447EroExp + 0.709, r2= 0.89, different of 1:1 relation, showing increasing overestimation with the magnitude of soilerosion: if estimation was 4 Mg.ha-1, the experimental value was 3.25 (23 % overestimation), if estimation was 8 Mg.ha-1, theexperimental value was 6.02 (33 % overestimation). The model overestimation not considering soil water content variation isrelevant around 7 Mg.ha-1, the most frequent tolerance value for Argiudolls; it is proposed to correct it using the regressionobtained in the present work.

Palabras clave : RUSLE; erosion; soil water content.

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