Development and analysis of the Soil Water Infiltration Global database.

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

GENERAL EDR FOR TRAPEZOIDAL FREE OVERFALL

Η δυνατότητα να χρησιμοποιηθεί ο καταβαθμός ελεύθερης υδατόπτωσης σαν κατασκευή για τη μέτρηση της παροχής, σε συνδυασμό με την περιορισμένη μέχρι τώρα έρευνα του τραπεζοειδούς καταβαθμού, έδωσαν αφορμή για τη μελέτη αυτή. Στην εργασία αυτή υιοθετείται η διαδικασία προσομοίωσης καταβαθμού με εκχειλιστή λεπτής στέψης, παίρνοντας υπόψη σύγκλιση των γραμμών ροής στο χείλος, και τελικά προκύπτει γενική σχέση μεταξύ του βάθους ροής στο χείλος του καταβαθμού της παροχής, η οποία ισχύει τόσο για υποκρίσιμη όσο και υπερκρίσιμη ροή. Στις αριθμητικές εφαρμογές που ακολουθούν, οι παροχές του τη μια και για πού υπολογίζονται συγκρίνονται με πειραματικές τιμές, καθώς επίσης και με τα αποτελέσματα δυο άλλων θεωρητικών μεθόδων.The use of the free overfall as a flow measuring device and the relatively few investigations of the trapezoidal free overfall were the reasons for this research. In this paper, the flow over a free overfall in a trapezoidalchannel is simulated with that over a sharp crested weir, taking into account the convergence of the streamlines at the brink, and a general end depth discharge relationship, for both subcritical and supercritical flow, is finally obtained. In the following numerical applications the discharges obtained using this relationship are compared with experimental data and with those predicted using two other theoretical methods

An optimum level of nano-selenium supplementation of a broiler diet according to the performance, economical parameters, plasma constituents and immunity

An optimum nano-Se content in a diet of highly productive broilers has not been defined yet. Meanwhile, there are contradictory reports regarding effects of nano-Se on production traits and the etiology of possible positive effects. The aims of the present study were to test the hypothesis that low levels of nano-Se can improve productivity and metabolic functions during a 42-day-long broiler production cycle, to determine an optimum nano-Selenium (nano-Se) concentration of the diet, and finally to explore the etiology of these effects. One-hundred-eighty 1-day-old, male, Ross 308 broiler chicks were used in a completely randomized experiment, where the birds were placed in experimental pens, in three replicate pens of 10 chicks each, making a total of 18 experimental units. They were assigned diets with different nano-Selenium levels. All birds were fed an almost identical diet from 1 until 42 d, different only in the nano-Se content, namely: 1) control (CON) group 0.0 nano-Se, 2) NS1 group 0.1 mg kg-1 dietary nano-Se, 3) NS2 group 0.2 mg kg-1 dietary nano-Se, 4) NS3 group 0.3 mg kg-1 dietary nano-Se, 5) NS4 group 0.4 mg kg-1 dietary nano-Se, 6) NS5 group 0.5 mg kg-1 dietary nano-Se, supplied from 1 to 42 day of life. The significance level was declared at P<0.05. The final bird weight was higher and production cost was lower in NS3 and NS4 groups compared to CON, NS1 and NS5. The weight of an eviscerated carcass was lower in CON group compared to the other groups. The serum blood parameters as well as the weight of organs related with the immune system were not significantly different between groups. Nano-Se supplementation positively affected body weight gain (BWG) and feed conversion ratio (FCR). Higher BWG was achieved owing to better FCR rather than higher feed intake. The supplementation of 0.3-0.4 mg nano-Se kg-1 is the optimum level to be added as a feed additive in broiler diets, increasing animal productivity and diminishing environmental impac

Simulation of Potassium Availability in the Application of Biochar in Agricultural Soil

Nutrient availability after fertilising agricultural soils is affected by many factors, including soil moisture conditions and physicochemical properties. Herein, the availability of potassium in soil enriched with biochar is studied, considering either saturated or unsaturated moisture conditions and questioning key ion exchange approaches, such as equilibrium exchange (E.E.) and kinetic exchange (K.E.). Potassium release is simulated from a soil–biochar mixture of 0, 0.5, 1 and 2% by coupling HYDRUS-1D and PHREEQC models. The water flow, mass transport and geochemical processes are simulated for a cultivation period that imitates agronomic and environmental conditions of a common agricultural field in Northern Greece. Potassium is released gradually during the irrigation period in the case of unsaturated flow conditions as opposed to its complete release over a few days in the case of saturated flow conditions in the soil. Regarding ion-exchange processes, the soluble amount of potassium is more readily available for transport in soil solution when using the E.E. approach compared to the K.E. approach that assumes a kinetically controlled release due to interactions occurring at the solid–solution interface. The increased proportion of biochar in soil results in a doubling of available potassium. Among the four modelling schemes, although the total mass of potassium released into soil solution is similar, there is a significant variation in release time, indicating that simplified saturated conditions may lead to unrealistic estimates of nutrient availability. Further experimental work will be valuable to decrease the uncertainty of model parameter estimation in the K.E. approach. © 2023 by the authors

Green Manuring for Low-input Irrigated Maize Cultivation as an Energy Crop in Mediterranean Climates

Introduction of high input crops to existing rotation schemes for bio-energy production such as corn in Mediterranean areas would only be possible by improving its yield and decreasing the cultivation costs. This work focusses on the combined effect of irrigation rate and green manuring on growth and productivity of irrigated corn grown in typical Mediterranean lowland. On a flat, calcareous clay-loam soil, a three-year field experiment was conducted. Pisum sativum was sown in specific plots every year in November and grew as cover crop under rainfed conditions until mid-April where its biomass was incorporated into the soil, while maize was sown by the end of April. A 3 × 2 factorial split-plot design was used in 3 blocks. Corn irrigation comprised the main plots and pea incorporation comprised the sub-plots. Soil moisture was monitored at weakly intervals at 10 layers of 10 cm each down to 1 m soil depth. Corn growth and final yield were monitored by means of distracting samplings. The overall conclusion is the significant positive effect of green manuring on corn biomass and seed yield. This effect was mainly attributed to greater water use efficiency as green manuring was associated with greater moisture content within the rooting zone compared to control plots. The increased yield obtained could offset the increased costs of growing pea as green manure (increase in farmers’ income of 20–110 € ha−1), allowing green manuring to become more widely used to reduce fertilization and irrigation inputs while also allowing corn to be introduced into current crop rotations for bio-energy production. © 2021, Springer Nature Switzerland AG

Adaptation of Mediterranean olive groves to climate change through sustainable cultivation practices

Olive cultivation is considered as one of the most significant agricultural activities in Greece, from a financial, social, and ecological point of view. Intensive cultivation practices in combination with the Mediterranean climate, lead to depletion of soil organic matter, erosion, desertification, and degradation of water resources. This paper describes sustainable olive crop management practices that were comparatively applied in 120 olive groves in Greece for 5 years with the participation of three farmers groups. Organic materials recycled in the olive groves during the present study were valuable sources of carbon, nitrogen, phosphorus, and potassium. Carbon content was highest in pruning residue (53.8-54.2%) while all materials studied were considered rich in C ranging between 41.9-46.2% (compost) and 34.9-42.5% (three-phase olive mill waste-OMW). The highest content in nitrogen was detected in compost (2-2.45%) followed by pruning residue (0.93-0.99%) and OMW (0.03-0.1%). Compost was considered a good source of phosphorus (0.3-0.6%) followed by pruning residue (0.08-0.13%) and OMW (0.01-0.3%). Potassium was also considerable in the organic materials recycled ranging 0.5-1.5% in compost followed by pruning residue (0.5-0.7%) and OMW (0.3-1.1%). Adoption of modified pruning also had important contribution toward sustainable management of olive trees. Sustainable pruning resulted in a well-balanced ratio between vegetative growth and fruiting (balanced, every year, in order to eradicate biennial bearing). Significant fluctuation in olive yields was observed in the first years of the project while yields were gradually stabilised by applying sustainable crop management. In parallel, yield increase without additional inputs, lowers the carbon-environmental footprint of the product regarding several environmental impact categories. Results can be integrated in the national agricultural and environmental policy in Mediterranean countries toward the achievement of a circular economy

Operational precise irrigation for cotton cultivation through the coupling of meteorological and crop growth models.

In this paper, we tested the operational capacity of an interoperable model coupling system for the irrigation scheduling (IMCIS) at an experimental cotton (Gossypium hirsutum L.) field in Northern Greece. IMCIS comprises a meteorological model (TAPM), downscaled at field level, and a water-driven cultivation tool (AquaCrop), to optimize irrigation and enhance crop growth and yield. Both models were evaluated through on-site observations of meteorological variables, soil moisture levels and canopy cover progress. Based on irrigation management (deficit, precise and farmer’s practice) and method (drip and sprinkler), the field was divided into six sub-plots. Prognostic meteorological model results exhibited satisfactory agreement in most parameters affecting ETo, simulating adequately the soil water balance. Precipitation events were fairly predicted, although rainfall depths needed further adjustment. Soil water content levels computed by the crop growth model followed the trend of soil humidity measurements, while the canopy cover patterns and the seed cotton yield were well predicted, especially at the drip irrigated plots. Overall, the system exhibited robustness and good predicting ability for crop water needs, based on local evapotranspiration forecasts and crop phenological stages. The comparison of yield and irrigation levels at all sub-plots revealed that drip irrigation under IMCIS guidance could achieve the same yield levels as traditional farmer’s practice, utilizing approximately 32% less water, thus raising water productivity up to 0.96 kg/m3.N/