Modelling Soil Water Content in a Tomato Field: Proximal Gamma Ray Spectroscopy and Soil–Crop System Models

Virginia Strati,Fausto Tomei,Stefano Anconelli,Marica Baldoncini,Barbara Fabbri,Giulia Villani,Domenico Solimando,Enrico Chiarelli,Kassandra Raptis,Carlo Bottardi,Fabio Mantovani,Matteo Albéri,Vincenzo Guidi,Marco Bittelli

doi:10.3390/agriculture8040060

Virginia Strati, Fausto Tomei + Show 12 more

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https://doi.org/10.3390/agriculture8040060

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Abstract

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.

Highlights

In the context of current global warming and uncertainty about future climate conditions, variation in rainfall amounts and dry spells frequency are expected to have negative impacts on the Agriculture 2018, 8, 60; doi:10.3390/agriculture8040060 www.mdpi.com/journal/agricultureAgriculture 2018, 8, 60 vegetation water availability and on crop yields and water productivity [1,2]
The aim of this study is to investigate the potentialities of proximal gamma ray spectroscopy for a real-time and continuous monitoring of soil water content in the framework of an ad hoc experiment
We report for the entire data-taking period temporal and speed, precipitation, and short wave incoming radiation (SWIR), the latter the measured withprofiles a of daily values recorded for the minimum and maximum temperatures

Summary

Introduction

In the context of current global warming and uncertainty about future climate conditions, variation in rainfall amounts and dry spells frequency are expected to have negative impacts on the Agriculture 2018, 8, 60; doi:10.3390/agriculture8040060 www.mdpi.com/journal/agricultureAgriculture 2018, 8, 60 vegetation water availability and on crop yields and water productivity [1,2]. Irrigation water, the primary input for agriculture development, is about two-thirds of the total fresh water assigned to human uses [3,4]. Significant improvements typically come from advanced technological systems aimed at optimizing water uptake both in terms of amounts of water required for the specific crop and of irrigation frequency [5]. Soil–crop systems models, designed for practical applications and decision support, are useful tools for providing a real-time estimate of the amount of water available to the crop [6]. The high temporal variation of soil properties, weather, and environmental conditions makes the modelling of soil water dynamics complex and problematic if not assisted with the running of expensive and time-consuming field monitoring of inter-temporal and site-specific parameters

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