Assessing the Effectiveness of Variable-Rate Drip Irrigation on Water Use Efficiency in a Vineyard in Northern Italy

Ortuani Ortuani,Mayer Mayer,Brancadoro Brancadoro,Facchi Facchi,Bianchi Bianchi

doi:10.3390/w11101964

Abstract

Although many studies in the literature illustrate the numerous devices and methodologies nowadays existing for assessing the spatial variability within agricultural fields, and indicate the potential for variable-rate irrigation (VRI) in vineyards, only very few works deal with the implementation of VRI systems to manage such heterogeneity, and these studies are usually conducted in experimental fields for research aims. In this study, a VR drip irrigation system was designed for a 1-ha productive vineyard in Northern Italy and managed during the agricultural season 2018, to demonstrate feasibility and effectiveness of a water supply differentiated according to the spatial variability detected in field. Electrical resistivity maps obtained by means of an electro-magnetic induction sensor were used to detect four homogeneous zones with similar soil properties. In each zone, a soil profile was opened, and soil samples were taken and analyzed in laboratory. Two irrigation management zones (MZs) were identified by grouping homogeneous zones on the basis of their hydrological properties, and an irrigation prescription map was built consistently with the total available water (TAW) content in the root zone of the two MZs. The designed drip irrigation system consisted of three independent sectors: the first two supplied water to the two MZs, while the third sector (reference sector) was managed following the farmer’s habits. During the season, irrigation in the first two sectors was fine-tuned using information provided by soil moisture probes installed in each sector. Results showed a reduction of water use by 18% compared to the ‘reference’ sector without losses in yield and product quality, and a grape’s maturation more homogeneous in time.

Highlights

Most climate projections predict that climate change will significantly affect the hydrological cycle leading, in many agricultural areas of the planet, to more frequent droughts and heat waves, to alteration of the spatial and temporal patterns of precipitation, to an increase in crop evapotranspiration, and to a general reduction of the available water for agriculture [1]
Four homogeneous soil types were identified through cluster analysis of electrical resistivity (ER) data, allowing to hypothesize a similar pattern of homogeneity in the hydrological characteristics of the soils
This work aimed at demonstrating the feasibility and the effectiveness of a simple variable-rate drip irrigation (VRDI) system in a 1 ha vineyard located in Northern Italy during the 2018 agricultural season, as a concrete possibility of adopting on-farm precision irrigation techniques to reduce water use while having positive effects on the production

Summary

Introduction

Most climate projections predict that climate change will significantly affect the hydrological cycle leading, in many agricultural areas of the planet, to more frequent droughts and heat waves, to alteration of the spatial and temporal patterns of precipitation, to an increase in crop evapotranspiration, and to a general reduction of the available water for agriculture [1]. In this scenario it is essential that research could focus on the development of ‘water saving’ technologies and techniques, with the ambitious goal to produce more with less (‘more crop per drop’, [2]). This is why a homogeneous irrigation application inevitably leads to areas within the same field constantly over-irrigated or under-irrigated with respect to optimal needs [5]

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Conclusion