Laboratory determination of soil hydraulic characteristics (HC) is performed on cylindrical confined soil cores, while resin‐coated small natural aggregates are prevalent for determining the Soil Shrinkage Characteristic Curve (SSCC). Because of the different geometry and volume of clods and cores, incorporation of shrinkage in HC of clay soils could be affected by the use of SSCC determined on natural aggregates or on confined cores. The objectives of this study were (i) to investigate differences between the SSCC obtained on resin‐coated natural aggregates (volume V = 20–30 cm3) and on cylindrical confined cores having a volume (650 cm3) close to that of cores used for HC laboratory determination, (ii) to test the performance of different models proposed for analytical interpretation of the SSCC, and (iii) to derive regression equations predicting the SSCC from routinely measured soil physical properties. Using twenty‐one Sicilian soils of variable shrink‐swell behavior, we found significantly larger specific volume (n), indicating less shrinkage, in the cylindrical confined cores. The investigation also proved the good fitting of a two‐line model to the measured SSCC and the possibility to predict the basic shrinkage line from the clay content. These results suggest that incorporation of shrinkage in HC of clay soils should be based on the SSCC measured or predicted on cores with geometry and dimensions as those used for routine laboratory measurement of HC.

Field-saturated soil hydraulic conductivity, Kfs, is highly variable. Therefore, interpreting and simulating hydrological processes,\ud such as rainfall excess generation, need a large number of Kfs data even at the plot scale. Simple and reasonably rapid\ud experiments should be carried out in the field. In this investigation, a simple infiltration experiment with a ring inserted shortly\ud into the soil and the estimation of the so-called a* parameter allowed to obtain an approximate measurement of Kfs. The\ud theoretical approach was tested with reference to 149 sampling points established on Burundian soils. The estimated Kfs with the\ud value of first approximation of a* for most agricultural field soils (a* = 0.012mm_1) differed by a practically negligible\ud maximum factor of two from the saturated conductivity obtained by the complete Beerkan Estimation of Soil Transfer parameters\ud (BEST) procedure for soil hydraulic characterization. The measured infiltration curve contained the necessary information to\ud obtain a site-specific prediction of a*. The empirically derived a* relationship gave similar results for Kfs (mean = 0.085mms_1;\ud coefficient of variation (CV) = 71%) to those obtained with BEST (mean = 0.086mms_1; CV = 67%), and it was also successfully\ud tested with reference to a few Sicilian sampling points, since it yielded a mean and a CV of Kfs (0.0094mms_1 and 102%,\ud respectively) close to the values obtained with BEST (mean = 0.0092mms_1; CV = 113%). The developed method appears\ud attractive due to the extreme simplicity of the experiment

The present study reviews the research on the FAO56 crop coefficients of fruit trees and vines performed over the past twenty years. The main objective was to update information and extend tabulated single (K c ) and basal (K cb ) standard crop coefficients. The selection and analysis of the literature for this review have been done to consider only studies that adhere to FAO56 method, computing the reference ET with the FAO Penman-Monteith ET o equation and field measuring crop ET with proved accuracy. The crops considered refer to vine fruit crops, berries and hops, temperate climate evergreen fruit trees, temperate climate deciduous fruit trees and, tropical and subtropical fruit crops. Papers satisfying the conditions expressed above, and that studied the crops under pristine or appropriate eustress conditions, were selected to provide for standard K c and K cb data. Preference was given to studies reporting on the fraction of ground cover (f c ), crop height (h), planting density, crop age and adopted training systems. The K c and K cb values obtained from the selected literature generally show coherence relative to the crop biophysical characteristics and reflect those characteristics, mainly f c , h and training systems. The ranges of reported K c and K cb values were grouped according to crop density, particularly f c and h, and were compared with FAO56 (Allen et al., 1998) previously tabulated K c and K cb values, as well as by Allen and Pereira (2009) and Jensen and Allen (2016), which lead to define update indicative standard K c and K cb values. These values are aimed for use in crop water requirement computations and modeling for irrigation planning and scheduling, thus also aimed at supporting improved water use and saving in orchards and vines.

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