Net irrigation requirement under different climate scenarios using AquaCrop over Europe

Global soil water availability is challenged by the effects of climate change and a growing population. On average 70 % of freshwater extraction is attributed to agriculture, and the demand is increasing. In this study, the effects of climate change on the evolution of the irrigation water requirement to sustain current crop productivity are assessed by using the FAO crop growth model AquaCrop version 6.1. The model is run at 0.5° lat × 0.5° lon resolution over the European mainland, assuming a general C3-type of crop, and forced by climate input data from the Inter-Sectoral Impact Model Intercomparison Project phase three (ISIMIP3). First, the performance of AquaCrop surface soil moisture (SSM) simulations using historical meteorological input from two ISIMIP3 forcing datasets is evaluated with satellite-based SSM estimates. When driven by ISIMIP3a reanalysis meteorology for the years 2011–2016, daily simulated SSM values have an unbiased root-mean-square difference of 0.08 and 0.06 m3m−3 with SSM retrievals from the Soil Moisture Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) missions, respectively. When forced with ISIMIP3b meteorology from five Global Climate Models (GCM) for the years 2011–2020, the historical simulated SSM climatology closely agrees with the climatology of the reanalysis-driven AquaCrop SSM climatology as well as the satellite-based SSM climatologies. Second, the evaluated AquaCrop model is run to quantify the future irrigation requirement, for an ensemble of five GCMs and three different emission scenarios. The simulated net irrigation requirement (Inet) of the three summer months for a near and far future climate period (2031–2060 and 2071–2100) is compared to the baseline period of 1985–2014, to assess changes in the mean and interannual variability of the irrigation demand. Averaged over the continent and the model ensemble, the far future Inet is expected to increase by 67 mm year–1 (+30 %) under a high emission scenario Shared Socioeconomic Pathway (SSP) 3-7.0. Central and southern Europe are the most impacted with larger Inet increases. The interannual variability of Inet is likely to increase in northern and central Europe, whereas the variability is expected to decrease in southern regions. Under a high mitigation scenario (SSP1-2.6), the increase in Inet will stabilize around 40 mm year–1 towards the end of the century and interannual variability will still increase but to a smaller extent. The results emphasize a large uncertainty in the Inet projected by various GCMs.

Crop water and irrigation requirements of some selected crops in southwestern hydrological zone of Nigeria

This study was carried out to determine the crop water and irrigation requirement of some selected crops in southwestern Nigeria. The crops are cucumber, water melon, maize, groundnut, eggplant and tomato. Irrigation requirement and crop coefficient for each crops were determined from the interrelationships of the evapotranspiration, soil type, bulk density, field capacity and the effective root zone of the crops at the selected locations using CROPWAT for windows version 8. Soil parameters used for analysis were determined from laboratory experiment. The crop evapotranspiration and water requirement for cucumber varied from 2.52 to 7.21mm/day and 17 to 73.2mm/dec, respectively, for maize from 1.36 to 6.35mm/day and 5.1 to 63.5mm/dec respectively, for watermelon varied from 2.59 to 6.67mm/day and 25.9 to 73.3mm/dec respectively, for eggplant varied from 1.92 to 6.35 mm/day and 15.9 to 64.4mm/dec respectively. The irrigation requirement for water melon and cucumber recorded the highest value of 461.6 and 497.4mm/dec respectively, an indication that the two crops require more water for physiological activities. The reduction in the values of crop coefficient was observed during the study which could be attributed to the reduction in evapotranspiration at the late stage of growth. The findings also showed that known quantities of irrigation water could be used in producing crops optimally.

Avocado cv. Hass Needs Water Irrigation in Tropical Precipitation Regime: Evidence from Colombia

The primary natural source of water for the Hass avocado crop in the tropics is precipitation. However, this is insufficient to provide most crops’ water requirements due to the spatial and temporal variability. This study aims to demonstrate that Hass avocado requires irrigation in Colombia, and this is done by analyzing the dynamics of local precipitation regimes and the influence of Intertropical Convergence Zone phenomena (ITCZ) on the irrigation requirement (IR). This study was carried out in Colombia’s current and potential Hass avocado production zones (PPA) by computing and mapping the monthly IR, and classifying months found to be in deficit and excess. The influence of ITCZ on IR by performing a metric relevance analysis on weights of optimized Artificial Neural Networks was computed. The water deficit map illustrates a 99.8% of PPA requires water irrigation at least one month a year. The movement of ITCZ toward latitudes far to those where PPA is located between May to September decreases precipitation and consequently increases the IR area of Hass avocado. Water deficit visualization maps could become a novel and powerful tool for Colombian farmers when scheduling irrigation in those months and periods identified in these maps.

ERA5-based global assessment of irrigation requirement and validation

While only 20% of harvested lands are actually irrigated, 40% of global agricultural production originates from irrigated areas. Therefore, assessing irrigation requirements is essential for the development of effective water-related policies for an efficient management of water resources. Moreover, global-scale analyses are becoming increasingly relevant, motivated by globalized production and international trade of food as well as by the need of common strategies to address climate change. In this study, a comprehensive model to estimate crop growth and irrigation requirements of 26 main crops at global scale is presented. The model computes a soil water balance using daily precipitation and reference evapotranspiration based on a high-resolution ERA5 reanalysis dataset from the European Copernicus Program. The irrigation requirement, defined as the minimum water volume to avoid water stress, is computed for year 2000 at the resolution of 5 arc-min (or 0.0833°) and aggregated at different spatial and temporal scales for relevant analyses. The estimated global irrigation requirements for 962 km3 is described in detail, also in relation to the spatial variability and to the monthly variation of the requirements. A focus on different areas of the world (California, Northern Italy and India) highlights the wealth of information provided by the model in different climatic conditions. National data of irrigation withdrawals have been used for an extensive comparison with model results. A crop-specific validation has also been made for the State of California, comparing model results with local data of irrigation volume and independent estimates of crop water use. In both cases, we found a good agreement between model results and real data.

Estimation Of Water Requirement Of Lycopersicon Esculentum Mill

Crop water requirements of Roma tomato that planted on different spacing for four treatment and its replications in Nyagatare district Kinihira village have been computed with CROPWAT 8.0 using the meteorological parameters. The water requirement was computed using evapotranspiration (ET0), effective rainfall, Net Irrigation demand, the Gross Irrigation demand and irrigation interval for crops grown in different treatment of different spacing have been computed. Based on the rainfall data, effective rainfall and soil characteristics of the experiment site, it was shown that the total net irrigation requirement of tomato in experiment site as presented in CROPWAT 8.0 is 286.2mm and the total gross irrigation requirement is 408.8mm.The total water loss during irrigation is obtained by taking the total gross irrigation requirement minus the total net irrigation requirement and found to be122.6mm. As per CROPWAT 8.0, Tomato water requirement in whole growing stages is 620.3mm .This total water required by tomato at experimental site was supplied to crop by rainfall as effective rainfall (211.5mm) and the remaining portion (408.8mm) was supplied to crop through irrigation. A wide spectrum of scenarios has been discussed in the paper along with the guidelines for future management of water resources.

Maize irrigation requirement on Zemun chernozem in the last half of the century

The aim of this paper is to examine the water regime of chernozem under maize crops in the last half century (1966-2019) and to determine whether during that period and to what extent, there was an increase or decrease in maize irrigation requirements. The mathematical plant model FAO CROPWAT 8.0 was used for the calculation. The calculation was performed on the basis of monthly values of reference evapotranspiration (ETo) for the period 1966-2019, calculated by the modified Hargreaves method, daily values of precipitation from the meteorological station Surcin, data on the selected plant, which are in accordance with FAO56. The soil is chernozem on the Zemun les terrace. The analysis was performed by dividing the research period into three subperiods: the first twenty (1966-1985), the second twenty (1986-2005) and the last fourteen (2006-2019) years. It was found that the average values of potential evapotranspiration of maize were increasing, starting from the first (500mm) to the third (562mm) subperiod, while the average values of actual evapotranspiration, as well as the average amount of effective precipitation in the vegetation period of maize, decreased. Consequently, the average water deficit, i.e. maize irrigation requirements was increased by 56%, starting from the first (205mm) to the third (319mm) subperiod of the research. The increase in the water deficit also caused an increase in the projected reduction in maize yield related to its genetic capasity, which averaged 31% in the first subperiod and 47% in the third. Analysis of the results on a monthly and decadal level showed that maize irrigation requirements lasts from June to August, with a maximum in the second decade of July. In all three summer months, an increase in maize irrigation requirements was registered from the first to the third subperiod of the research, with the maximum increase during July. The conducted research, which generally gives an insight into the state of the water regime of Zemun chernozem in the last half century, shows that the conditions of maize production in the natural rain regime are deteriorating and that the irrigation requirement is increasing.