Abstract. In this paper, we present and analyze a novel global database of soil infiltration measurements, the Soil Water Infiltration Global (SWIG) database. In total, 5023 infiltration curves were collected across all continents in the SWIG database. These data were either provided and quality checked by the scientists who performed the experiments or they were digitized from published articles. Data from 54 different countries were included in the database with major contributions from Iran, China, and the USA. In addition to its extensive geographical coverage, the collected infiltration curves cover research from 1976 to late 2017. Basic information on measurement location and method, soil properties, and land use was gathered along with the infiltration data, making the database valuable for the development of pedotransfer functions (PTFs) for estimating soil hydraulic properties, for the evaluation of infiltration measurement methods, and for developing and validating infiltration models. Soil textural information (clay, silt, and sand content) is available for 3842 out of 5023 infiltration measurements (∼ 76%) covering nearly all soil USDA textural classes except for the sandy clay and silt classes. Information on land use is available for 76 % of the experimental sites with agricultural land use as the dominant type (∼ 40%). We are convinced that the SWIG database will allow for a better parameterization of the infiltration process in land surface models and for testing infiltration models. All collected data and related soil characteristics are provided online in *.xlsx and *.csv formats for reference, and we add a disclaimer that the database is for public domain use only and can be copied freely by referencing it. Supplementary data are available at https://doi.org/10.1594/PANGAEA.885492 (Rahmati et al., 2018). Data quality assessment is strongly advised prior to any use of this database. Finally, we would like to encourage scientists to extend and update the SWIG database by uploading new data to it.

Soil water retention data are fundamental in soil modeling studies. Temperate pedotransfer functions (PTFs) have been commonly used to estimate water retention of Brazilian soils, mainly because of the lack of soil data for Brazil. However, these PTFs may not be suitable for tropical or subtropical conditions such as those found in Brazil. The objective of this study was to establish a dedicated Hydrophysical Database for Brazilian Soils (HYBRAS) suitable for PTF development. Data present in HYBRAS comprise 445 soil profiles with 1075 samples and are representative of a wide range of Brazilian soils. The data are organized in a relational structure of tables that cover general site descriptions, land cover, and hydrophysical and chemical measurement methods. Raw data (e.g., water retention points covering the 0-15,000-cm suction range) and derived data are included in the tables. Another objective of this study was to use the database to compare the accuracy of water retention estimates based on PTFs developed for Brazilian and temperate regions. In general, the Brazilian PTFs performed better than the temperate models, especially for weathered (Ferralsols, Acrisols, and Nitisols) finetextured (clay, sandy clay, clay loam, silty clay loam, and silty clay) soils. Silt content was not a successful criterion for distinguishing performance of Brazilian and temperate PTFs for Brazilian weathered soils. The water retention of weathered soils was shown to differ from that of temperate soils due to differences in pore structure resulting from their clay content and mineralogical nature, thus confirming results reported in the literature.Abbreviations: HYBRAS, Hydrophysical Database for Brazilian Soils; HYPRES, Hydraulic Properties of European Soil; ME, mean error; pF, log 10 suction; PTF, pedotransfer function; UNSODA, Unsaturated Soil Hydraulic Database; VG, van Genuchten.Soil water retention data are fundamental in soil modeling studies. Their direct measurement is costly and demands intense field work, which makes it infeasible for large areas. As a result, pedotransfer functions (PTFs) (Bouma, 1989) are being developed and used increasingly to estimate water retention data from routinely available soil measures.Brazil plays an important role in the development of tropical water retention PTFs (Botula et al., 2014). Barros and de Jong van Lier (2014) extensively reviewed water retention PTFs for Brazilian soils. These PTFs are commonly developed to estimate the available water content on the basis of field capacity and permanent wilting point, with their use often restricted to certain types of soils or geographic regions (Barros and de Jong van Lier, 2014). To our knowledge and according to Barros and de Jong van Lier (2014), the studies by Tomasella and Hodnett (1998), Tomasella et al. (2000Tomasella et al. ( , 2003, da Silva (2002), de Mello et al. (2005), Fidalski and Tormena (2007), da Silva et al. (2008), Fiorin (2008, Barros et al. (2013) and Medrado and Lima (2014) are the main publications on PTF developme...

SUMMARYTaking into account the nature of the hydrological processes involved in in situ measurement of Field Capacity (FC), this study proposes a variation of the definition of FC aiming not only at minimizing the inadequacies of its determination, but also at maintaining its original, practical meaning. Analysis of FC data for 22 Brazilian soils and additional FC data from the literature, all measured according to the proposed definition, which is based on a 48-h drainage time after infiltration by shallow ponding, indicates a weak dependency on the amount of infiltrated water, antecedent moisture level, soil morphology, and the level of the groundwater table, but a strong dependency on basic soil properties. The dependence on basic soil properties allowed determination of FC of the 22 soil profiles by pedotransfer functions (PTFs) using the input variables usually adopted in prediction of soil water retention. Among the input variables, soil moisture content θ θ θ θ θ (6 kPa) had the greatest impact. Indeed, a linear PTF based only on it resulted in an FC with a root mean squared residue less than 0.04 m 3 m -3 for most soils individually. Such a PTF proved to be a better FC predictor than the traditional method of using moisture content at an arbitrary suction. Our FC data were compatible with an equivalent and broader USA database found in the literature, mainly for medium-texture soil samples. One reason for differences between FCs of the two data sets of finetextured soils is due to their different drainage times. Thus, a standardized procedure for in situ determination of FC is recommended.Index terms: internal drainage, aeration capacity, soil water retention. Levando em conta a natureza dos processos hidrológicos envolvidos na medição da Capacidade de Campo (CC) in situ, este estudo propõe uma variação da definição de CC a fim de minimizar as impropriedades de sua determinação, mas também de manter seu sentido prático original. A análise de dados de CC para 22 solos brasileiros e de dados adicionais da literatura, todos medidos segundo a definição proposta, que é com base no tempo de drenagem de 48 h após uma infiltração por alagamento raso, indicou fraca dependência na quantidade de água infiltrada, valor de umidade antecedente, morfologia do solo e nível do lençol freático, mas forte dependência nas propriedades básicas do solo. Essa dependência nas propriedades básicas do solo permitiu a determinação da CC dos 22 perfis de solo por funções de pedotransferência (FPTs), utilizando as variáveis de entrada usualmente adotadas na predição de retenção de água no solo. Entre as variáveis de entrada, a umidade θ (6 kPa) foi a que teve maior impacto; de fato, uma FPT linear com base somente nela resultou numa CC com raiz quadrada de resíduo quadrático médio menor que 0,04 m³ m -³, individualmente para todos os solos. Foi evidenciado que tal FPT foi um melhor avaliador da CC do que o método tradicional que utiliza diretamente a umidade a uma sucção arbitrária. Os dados de CC foram compatíveis com uma base de ...

Abstract. In this paper, we present and analyze a global database of soil infiltration measurements, the Soil Water Infiltration Global (SWIG) database, for the first time. In total, 5023 infiltration curves were collected across all continents in the SWIG database. These data were either provided and quality checked by the scientists who performed the experiments or they were digitized from published articles. Data from 54 different countries were included in the database with major contributions from Iran, China, and USA. In addition to its global spatial coverage, the collected infiltration curves cover a time span of research from 1976 to late 2017. Basic information on measurement location and method, soil properties, and land use were gathered along with the infiltration data, which makes the database valuable for the development of pedo-transfer functions for estimating soil hydraulic properties, for the evaluation of infiltration measurement methods, and for developing and validating infiltration models. Soil textural information (clay, silt, and sand content) is available for 3842 out of 5023 infiltration measurements (~76 %) covering nearly all soil USDA textural classes except for the sandy clay and silt classes. Information on the land use is available for 76 % of experimental sites with agricultural land use as the dominant type (~40 %). We are convinced that the SWIG database will allow for a better parameterization of the infiltration process in land surface models and for testing infiltration models. All collected data and related soil characteristics are provided online in *.xlsx and *.csv formats for reference, and we add a disclaimer that the database is for use by public domain only and can be copied freely by referencing it. Supplementary data are available at doi:10.1594/PANGAEA.885492. Data quality assessment is strongly advised prior to any use of this database. Finally, we would like to encourage scientists to extend/update the SWIG by uploading new data to it.

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