The major global challenge for the coming decades will be increasing crop production with less water consumption. Precision agriculture (PA) and variable deficit irrigation (VDI) are management strategies that help farmers to improve crop production, fertilizer’s efficiency, and water use efficiency (WUE). The effects of irrigation (IR1 = variable deficit irrigation; IR2 = farmers’ irrigation common practices) under three fertilization (Ft1, Ft2, Ft3) treatments were studied on a cotton yield, on various indicators for more efficient water and fertilizer use, and on plant growth characteristics by applying a number of new agrotechnologies (such as TDR sensors; soil moisture (SM); PA; remote-sensing NDVI (Sentinel-2 satellite sensors); soil hydraulic analyses; geostatistical models; and SM root-zone modelling 2D GIS mapping). The reference evapotranspiration was computed based on the F.A.O. Penman–Monteith method. The crop (ETc) and actual (ETa) evapotranspiration were computed using crop coefficients obtained from the remote-sensing NDVI vegetation index (R² = 0.9327). A daily soil–water–crop–atmosphere (SWCA) balance model and a depletion model were developed using sensor data (climatic parameters’ sensors, as well as soil and satellite sensors) measurements. The two-way ANOVA statistical analysis results revealed that irrigation (IR1 = best) and fertilization treatments (Ft2 = best) significantly affected the cotton yield, the plant height, the plant stem, the boll weight, the above-ground dry matter, nitrogen and fertilizer efficiency, and WUE. VDI, if applied wisely during critical growth stages, could result in a substantial improvement in the yield (up to +28.664%) and water savings (up to 24.941%), thus raising water productivity (+35.715% up to 42.659%), WUE (from farmers’ 0.421–0.496 kg·m⁻³ up to a VDI of 0.601–0.685 kg·m⁻³), nitrogen efficiency (+16.888% up to +22.859%), and N-P-K fertilizer productivity (from farmers’ 16.754–23.769 up to a VDI of 20.583–27.957).

The aim of this project was to conduct research into the effect of irrigation interval, using drip irrigation, on the depletion of available soil moisture and on corn yield, and the possible savings it might bring about in water, manpower, energy and other overheads. The experiments were carried out between 2000 and 2001 in the plain of Thessaly, central Greece. The experimental field had a complete randomized block design and consisted of three treatments (i.e. irrigation every 2, 5 and 9 days) for four replicates. Daily measurements were taken of the soil moisture content using the time domain reflectrometry (TDR) method and the depletion of available soil moisture was calculated. The amount of water used in each irrigation session was equal to the cumulative evapotranspiration between two successive irrigation sessions as measured using evaporation pan type A.Results showed that irrigation could be carried out every nine days instead of every two or even five days, thus bringing about substantial savings in the consumption of water. In addition, other overheads such as manpower, energy, etc. could be cut down with no statistically significant difference in crop yield. Copyright © 2008 John Wiley & Sons, Ltd.

The scope of present work was the modelling and mapping of maize biomass yield in correlation with water quality and irrigation water management effects in an experimental field with combinational use of in situ measurements and Information and Communication Technologies (ICT) such as Geographic Information Systems (GIS), Global Positioning System (GPS), Geostatistical modeling. The investigation of drip irrigation frequency effects in yield and in the proportion of biomass in the various plant parts and in the distribution of soil moisture were studied, in an experimental parcel of three interventions (i.e. irrigation per 9, 12 and 15 days) in a four replications, randomized complete block design (RCBD) with systematic plot arrangement, in a farm located in central Greece (Larissa), at the farming period of year 2003. The cut plants fractions results for the distribution of above ground biomass (dry matter), were: 47.74% grain, 26.72% stalk, 11.43% leaf, 7.25% cob, 6.86% husk, and for the distribution of...

Precision agriculture (PA), management zone (MZ) strategies at the field level, soil analyses, deficit irrigation (DI), and fertilizer Variable Rate Application (VRA) are management strategies that help farmers improve crop production, fertilizer use efficiency, and irrigation water use efficiency (IWUE). In order to further investigate these management strategies, the effects of four soil MZ treatments, which were delineated using PA with fuzzy k-means clustering, two irrigation levels [IR1:FI = full drip irrigation (>90% of ${\theta }_{fc}$), IR2:VDI = variable deficit drip irrigation (60–75% of ${\theta }_{fc}$)], and four VRA fertilizations were studied on coriander yield and essential oil content in a two-year research project in Greece. A daily soil-water-crop-atmosphere (SWCA) balance model and a daily depletion model were developed using sensor measurements (climatic parameter sensors as well as soil moisture sensors). Unbalanced one-way ANOVA (p = 0.05) statistical analysis results revealed that correct delineation of MZs by PA with fuzzy k-means clustering, if applied under deficit irrigation and VRA fertilization, leads to increased essential oil content of coriander with statistically significant differences (SSD) and lower fruit yields; however, without SSD differences among management zones, when appropriate VRA fertilization is applied to leverage soil nutrient levels through the different fuzzy clustered MZs for farming sustainability. Moreover, VDI compared to full irrigation in different MZs yields 22.85% to 29.44% in water savings, thus raising IWUE (up to 64.112 kg m⁻³), nitrogen efficiency (up to 5.623), and N-P-K fertilizer productivity (up to 5.329).

The aim of the present study was to determine the effects of rainfed and supplemental irrigation, and sowing period (SP) treatments on coriander (Coriandrum sativum L.) yield, essential oil content and umbel heights by applying new agro-technologies (TDR-sensors for soil moisture (SM), geographical information system (GIS), precision agriculture, soil-hydraulic analyses and geostatistical models) for yield and SM root zone geospatial modelling and two-dimensional GIS mapping. Results of laboratory analysis indicated a suitable soil for coriander's growth and revealed that field's soil was characterized sandy clay loam (SCL) with mean values: soil organic matter (SOM) = 1.70%, bulk specific gravity = 1.42 g·cm−3, plant available water = 0.129 cm·cm−1, pH = 7.10 and cation-exchange capacity (CEC) = 19.3 cmol·kg−1. The two-way ANOVA statistical analysis (P = 0.05) results revealed that the irrigation treatments (IR1: rainfed, IR2: rainfed plus supplemental irrigation [best]), and the SP treatments (SP1: October's last week, SP2: November's first week [best]) significantly affects coriander's seed yield and essential oil content, but the SP have no significant effect on plant's umbel height (P = 0.873). Supplemental irrigation, using a limited amount of water, if applied during the critical crop growth stages, can result in substantial improvement on seed yield (+284.934%), essential oil content (+125.396%) and plant's umbel height (+117.929%).

The aim of the present study is a hydrological approach on streamflow modelling, in order to investigate flow velocity, discharge rate, stage, river bed variations and the hydraulic properties (water depth, flow area, wetted perimeter, hydraulic radius and depth, Manning’s coefficient of roughness, Froude Number, etc.) of the Pinios River at P145 Giannouli-Larissa monitoring station (Central Greece). Also, the study aims to the compilation–validation of a rating curve (RC) from a series of stage h(t)–discharge Q(t) pairs measurements, in order to use them as tools to assist environmental and agricultural water resources management, support environmental flows estimation, monitoring and irrigation planning in local basin scale. The results and statistical analysis, showed that Froude number during the measurement period oscillated from a minimum 0.109 to maximum 0.283 (mean Fr = 0.172). Therefore, in all cases, Fr < 1 which means that streamflow of the River Pinios, at P145 station is classified as subcritical. The segment’s maximum water velocity measured from a minimum 0.452 to maximum 1.693 m s⁻¹ (mean 1.247). The mean monthly river discharges of years 1978, 1979 and 2014 were found to be 35.91, 57.52 and 50.37 m³ s⁻¹, respectively. The summer months (June–August) of recent and also of historic years presented low to zero discharges, which are below the environmental flow lower (critical) limit. Moreover, based on the parameters’ measurements from 2013 (July) up to 2014 (December), on the modelling analysis, on classification results and on the proposed model performance index (MPI) for each of the eight models tested, the power model was selected as the best to use for the compilation and best fit of the flow RC for this monitoring station. The results of model’s validation using two different statistical methods, model simulation, error statistics criteria and the proposed MPI index, were converge to the same output that the data fitting the selected power model for the curve RC_{(2013–2014)} was very satisfactory, and the stability of the developed relationship was robust. The resulted streamflow RC and the extrapolated parts, the rainfall vs. discharge and environmental flows analysis, the river bed variation analysis and the performed hydraulic properties estimates are proposed to serve as hydrological assisting tools for environmental water resources and irrigation management at the study area. These assisting tools will help water authorities accurately and quickly estimate river’s water quantities and variation with a minimum cost and effort, and they could be used for irrigation management, environmental flow estimation, groundwater recharge, flood protection and other purposes.