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.
Olive-mill wastewater (OMW) is a by-product effluent of olive oil extraction process that is produced in large amount in the Mediterranean region. OMW is believed to induce phytotoxic effect on organisms including seed germination and plant growth. The objective of this study was to evaluate the impact of untreated and treated OMW with different techniques on seed germination of barley (Hordeum vulgare L.). The following treatments were investigated: (1) tap water (control); (2) OMW treated by aerobic biological technology in a Jacto Reactor (JR); (3) OMW treated by solar fenton oxidation (SFO); (4) OMW treated by microfiltration followed by nanofiltration (MF+NF); (5) OMW treated by microfiltration followed by reverse osmosis (MF+RO) process; (6) diluted OMW with tap water (25 % OMW); (7) diluted OMW with tap water (50 % OMW); (8) diluted OMW with tap water (75 % OMW); and (9) untreated OMW (100 % OMW). A germination test was conducted in an incubator at temperature of 23 (∘)C. In each petri dish, a filter paper was mounted and ten seeds of barley were placed on the filter paper. Five milliliter of water were added to each petri dish. The seed germination was determined by counting the number of germinated seeds to calculate the percentage of germination (G %). Germination rate index (GRI), seed vigor index (SVI), and phytotoxicity index (PI) were also calculated. Then, the dry weights and lengths of the shoots and the roots of the germinated seeds were measured. The results show that 100, 75, and 50 %OMW were very phytotoxic and completely prohibited seed germination. However, phytotoxicity decreased significantly following treatments of OMW with all techniques investigated and by the 25 % OMW dilution, as results of removing the phenols and other phytotoxic organic compounds from the OMW or by diluting it. This was evidenced by relative enhancement of the dry weights and lengths of shoot and root as well as the G %, GRI, SVG, and PI. It was concluded that if OMW will be used for irrigating crops, it has to be first treated or diluted with tap water at a ratio of 1:3 OMW:water at least. The most efficient treatment techniques in reducing the phytotoxicity of OMW were the MF+RO, followed by SFO and JR.
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