Evapotranspiration simulated by CRITERIA and AquaCrop models in stony soils

The performance of a water balance model is also based on the ability to correctly perform simulations in heterogeneous soils. The objective of this paper is to test CRITERIA and AquaCrop models in order to evaluate their suitability in estimating evapotranspiration at the field scale in two types of soil in the Mediterranean region: non-stony and stony soil. The first step of the work was to calibrate both models under the non-stony conditions. The models were calibrated by using observations on wheat crop (leaf area index or canopy cover, and phenological stages as a function of degree days) and pedo-climatic measurements. The second step consisted in the analysing the impact of the soil type on the models performances by comparing simulated and measured values. The outputs retained in the analysis were soil water content (at the daily scale) and crop evapotranspiration (at two time scales: daily and crop season). The model performances were evaluated through four statistical tests: normalised difference (D%) at the seasonal time scale; and relative root mean square error (RRMSE), efficiency index (EF), coefficient of determination (r2) at the daily scale. At the seasonal scale, values of D% were less than 15% in stony and on-stony soils, indicating a good performance attained by both models. At the daily scale, the RRMSE values (2) indicate the inadequacy of AquaCrop to simulate correctly daily evapotranspiration. The higher performance of CRITERIA model to simulate daily evapotranspiration in stony soils, is due to the soil submodel, which requires the percentage skeleton as an input, while AquaCrop model takes into account the presence of skeleton by reducing the soil volume

Modelling soil water conent in a tomato field: proximal gamma ray spectroscopy and soil-crop system models

Proximal soil sensors are taking hold in the understanding of soil hydrogeological processes involved in precision agriculture. In this context, permanently installed gamma ray spectroscopy stations represent one of the best space-time trade off methods at field scale. This study proved the feasibility and reliability of soil water content monitoring through a seven-month continuous acquisition of terrestrial gamma radiation in a tomato test field. By employing a 1 L sodium iodide detector placed at a height of 2.25 m, we investigated the gamma signal coming from an area having a ~25 m radius and from a depth of approximately 30 cm. Experimental values, inferred after a calibration measurement and corrected for the presence of biomass, were corroborated with gravimetric data acquired under different soil moisture conditions, giving an average absolute discrepancy of about 2%. A quantitative comparison was carried out with data simulated by AquaCrop, CRITeRIA, and IRRINET soil-crop system models. The different goodness of fit obtained in bare soil condition and during the vegetated period highlighted that CRITeRIA showed the best agreement with the experimental data over the entire data-taking period while, in presence of the tomato crop, IRRINET provided the best results.Comment: 18 pages, 9 Figures, 3 Table

evapotranspiration of tomato simulated with the criteria model

The CRITERIA model simulates crop development and water dynamics in agricultural soils at different spatial scales. The objective of this paper was to test CRITERIA in order to evaluate the suitability of the model as a tool for scheduling irrigation at field scale. The first step of the work was to validate this hypothesis, by means of calibration and validation of CRITERIA on processing tomato in two experimental sites in Southern Italy (Rutigliano and Foggia) for the years 2007 and 2008 under different irrigation regimes. The irrigation treatments were: i) absence of plant water stress (the control treatments set up for both years and sites), ii) moderately stressed (applied in Rutigliano for 2007), and iii) severely stressed (applied in Foggia for 2008). The second step consisted in the evaluation of the expected impact of different irrigation regimes on daily actual evapotranspiration. For model calibration, the 2007 data of the control treatment was used, whereas in the validation process of actual evapotranspiration, the other part of the dataset was used. The observed data were crop evapotranspiration, agrometeorological data, leaf area index, physical-chemical and hydrological characteristics of soil, phenological stages and irrigation management. In order to evaluate model performance we used three statistical indicators to compare simulated and measured values of actual evapotranspiration: the normalized differences of seasonal values are less than 10% for all treatments; the model efficiency index on the typical period between two irrigations (4 days) was positive for all treatments, with the best values in the Foggia site, for both the irrigated and the severely stressed experiments; the relative root mean square error (RRMSE) was smaller than 20% in both the control treatments, but higher than 30% for the stressed treatments. The increase in RRMSE for the stressed experiments is due to CRITERIA simulating a crop in good soil water conditions and, as a consequence, with a larger evapotranspiration demand with respect to water stressed crop. Therefore, we can consider CRITERIA as a suitable tool to manage irrigations of processed tomato, especially for the full irrigation regime; an improvement can be reached by simulating the impact of water stress conditions on the eco-physiological parameters of the crop, in order to use the model also under deficit irrigation regimes

Evaluation of groundwater contamination sources by plant protection products in hilly vineyards of Northern Italy

Abstract In Europe, 25% of groundwater has poor chemical status. One of the main stressors is agriculture, with nitrates and plant protection products (PPPs) causing failure in 18% and 6.5%, respectively, of groundwater bodies (by area). EU legislation for the placement of the PPPs on the market is one of the most stringent in the world. However, recent monitoring studies in hilly vineyards of Tidone Valley, north-west of Italy, show presence of PPPs used for grapevine cultivation in 15 out of 26 groundwater wells monitored, at values above the Environment Quality Standard (EQS) for groundwater (0.1 μg/L). However, no information about the contamination sources are available. Therefore, the objective of the present work is to evaluate the groundwater contamination sources by PPPs, in a small catchment with intensive viticulture, by collecting and integrating monitoring data, sub-surface water movement data and territorial characteristics. The results show that in wells used for PPP's mixture preparation and sprayer washing located at the top of hilly vineyards, with low slope and no water movement in the surrounding soil, the contamination is most likely from point sources. On the contrary, for wells located in a fenced area at the bottom of the hill, far away from vineyards and being used for drinking water production, the contamination is most likely from diffuse sources. Our results were used to raise awareness on groundwater contamination from PPPs among farmers in the study area; moreover a waterproof platform for sprayers washing, equipped with wastewater recovery and disposal system, able to avoid point-source contamination, was implemented in a local demonstration farm. Several demonstration activities were then organised with the farmers of the entire Valley in order to show its functionality and promote its diffuse use

Development and Testing of a Physically-Based, Three-Dimensional Model of Surface and Subsurface Hydrology

We present a numerical, catchment-scale model that solves flow equations of surface and subsurface flow in a three-dimensional domain. Surface flow is described by the two-dimensional parabolic approximation of the St. Venant equation, using Manning¿s equation of motion; subsurface flow is described by the three-dimensional Richards¿ equation for the unsaturated zone and by three-dimensional Darcy¿s law for the saturated zone, using an integrated finite difference formulation. The hydrological component is a dynamic link library implemented within a comprehensive model which simulates surface energy, radiation budget, snow melt, potential evapotranspiration, plant development and plant water uptake. We tested the model by comparing distributed and integrated three-dimensional simulated and observed perched water depth (PWD), stream flow data, and soil water contents for a small catchment. Additional tests were performed for the snow melting algorithm as well as the different hydrological processes involved. The model successfully described the water balance and its components as evidenced by good agreement between measured and modeled data.JRC.DDG.H.5-Rural, water and ecosystem resource

New mu-Oxo Octanuclear Complexes of 3d Elements Stabilized by Dialkylcarbamato Ligands. Synthesis, and X-Ray Crystal and Molecular Structures

ABSTRACT The octanuclear aggregates M8(mu4-O)2(O2CNiPr2)12 [M = Mn(II) 1, Co(II) 2, Ni(II) 3] have been prepared in good yields by controlled hydrolysis of the corresponding metal carbamate precursors [M(O2CNiPr2)2]n. X-ray analysis has shown compounds 1-3 to be isostructural. The core of 2 contains two distorted {M4O} tetrahedra related by an inversion center. The hexanuclear carbamates M6(O2CNEt2)12 in toluene undergo a metal redistribution process with formation of the hexanuclear carbamates M'xM' '6-x(O2CNEt2)12, M' = Co, M' ' = Mn, as evidenced by mass-spectrometric data. In the presence of moisture, the mixed octanuclear carbamates CoxMn6-x(MnO)(CoO)(O2CNEt2)12 were promptly formed and detected by DCI/MS measurements. Mass spectral data of Co8(mu4-O)2(O2CNiPr2)12 are also reporte

Measurement of soil bulk density and water content with time domain reflectometry: Algorithm implementation and method analysis

Time domain reflectometry can be applied to measure soil bulk density. Monitoring of bulk density over large areas for geo-statistical analysis requires a fast and effective method allowing for acquisition of many data points. Methods are available in the literature to obtain density from TDR. However, algorithms for simultaneous measurements of density and soil water content are not available. Moreover, the methodologies presented in the literature requires tests and evaluation. In this study a new algorithm implemented into a software was developed and the method tested over samples having different textural properties. It is shown that the method provided a measurement of density with an accuracy between 1 and 3 %. The new algorithm implements an automated methodology combined with a non-linear least square optimization, allowing for analysis of many waveforms at a time. Several equations to derive soil water content from electric permittivity were tested, showing that dielectric mixing models provides more accurate results. Moreover, the optimization of parameters allows for analysis and application to multiple materials. The method was confirmed robust and suitable for fieldmonitoring applications

Soil Water Balance Model CRITERIA-ID in SWAMP Project: Proof of Concept

The aim of this work is to present the first results obtained by means of the new validation of the water balance and crop development model CRITERIA-ID, specifically set up for the SWAMP (Smart Water Management Platform) platform on one of the pilots, in the framework of the SWAMP project, aimed at providing support for precision irrigation in agriculture. The platform consists of an IoT solution for monitoring the farming and irrigation systems combined with data analytic solution to assess the irrigation need of plants, and support for irrigation planning and water distribution both at farm and district level. CRITERIA-ID has been tested on two test cases for the Italian pilot, located in the land reclamation and irrigation consortium of Emilia Centrale (North Italy). The comparison of crop irrigation water needs computed by CRITERIA-ID with actual irrigation performed by farmers has been carried out, together with a comparison of crop water stress. The analysis has shown that for both the test cases the two data series are comparable, but some differences have been highlighted: in some cases the farmer irrigation is not decided on the basis of the actual water needs of the crops but on farm management decisions. In addition, if the total annual volumes of irrigation of the two series are comparable, the scheduling is different, where the observed irrigation data bring the crop to too high (or too low) level of water stress. Thus, the present work has shown that the application of CRITERIA-ID simulation model is a valid tool to support irrigation management because it allows an optimal use of the resource avoiding crop yield losses with a rational irrigation scheduling. The reliability of these outcomes sets the conditions for further exploitation of the model in the future, firstly for its integration into the SWAMP platform