Analysis of infiltration and runoff in an olive orchard under no-till

Four infiltration techniques (falling head, ring, rainfall, and tension inf iltrometer) were used to determine the saturated hydraulic conductivity, K- s, and the wetting potential front, h(f), of the Green-Ampt model. Water re lease curves from soil cores were also used for estimating h(f). The object ive was to compare the performance of the different techniques for the asse ssment of infiltration in a no-tillage olive (Olea europaea L, subsp, europ aea) orchard. Measurements were performed in two areas of the orchard, belo w canopy (C) and interrow among trees (IR), With the exception of the tensi on infiltrometer, all techniques showed significant differences in K-s and h(f) between C and IR areas, attributed to different compaction. Difference s in K-s among techniques were within the range observed previously. The h( f) estimated from the falling-head technique was significantly higher than that measured with the other techniques. The discrepancies in the results o btained with the tension infiltrometer were attributed to insufficient time of measurement, leading to recommendations for a different field procedure and analysis of this technique. To assess the use of the techniques descri bed above for the characterization of plot infiltration, rainfall and runof f were measured in a 128-m(2) plot. A numerical model was then used to pred ict runoff using the infiltration measurements. The results showed that run off prediction is improved when different values of K-s and h(f) are consid ered for the C and IR areas instead of a single average value. The numerica l analysis of the effects of tree arrangement on runoff prediction from inf iltration measurements indicated that if the trees were placed along the co ntour lines, runoff would decrease relative to the standard tree arrangemen t.