How new portable technology is redefining the agrohydrological sector

In this exclusive interview, we speak with Dr. Giovanni Rallo, an associate professor in the Department of Agricultural, Food and Agro-Environmental Sciences at the University of Pisa, to learn how the AgroHydrological Sensing and Modeling (AgrHySMo) laboratory uses the ASD FieldSpec 4 Standard-Res Spectroradiometer from Malvern Panalytical to reveal hidden information about plant-water relationships.

What are the overall aims of the AgrHySMo Lab?

The AgrHySMo lab harmonizes the three pillars of knowledge (research, application, and teaching) with the aim of transferring these to the irrigation industry and higher education sectors. Therefore, our research is always motivated to address critical societal needs through technological advances. Moreover, our work can be applied for drought mitigation and converging social crises concerning the use of water resources. The integration of such “Third Mission” activities with agronomic-based research sectors addresses the question of optimal irrigation management, including how to manage existing water stress with the most modern water-saving strategies, as opposed to finding out how to avoid it.

For this purpose, all suggested technologies for scheduling irrigation are associated with feed-forward and feed-back control irrigation protocols. With feed-forward protocols, the crop water requirements are simulated by agrohydrological or spectral models. With feed-back control of irrigation, the farmer maintains the soil-crop water status within a certain pre-defined range and acquires an awareness of this status through ordinary and spectral sensor systems, at the local or distributed scale.

What projects are the AgrHySMo Lab working on at the moment?

The AgrHySMo Lab has six research lines aimed to develop smart systems and innovative protocols for water resource management at the micro and mesoscale. Two of these projects are at the frontier of the agrohydrological sector.

At the moment, the laboratory is running a project focusing on my invention, the ATMOSMART – a system for the determination of the real evapotranspiration of a vegetated surface (patents WO2019244057A1; IT201800006477A1). One new advancement of ATMOSMART involves the implementation of micro-mechatronics elements developed by Prof. Vishnu Sundaresan of the Integrated Material Systems Laboratory, University of Ohio.

Another facet of this research regards the application of field spectroscopy to perform very fine vegetation water status monitoring protocols. For this research line, we aim to estimate the vegetation water potential components and the pressure-volume curve parameters on intact olive vegetative organs.

The aim is to combine these two projects to define a sophisticated device for determining the precise irrigation amount using the ATMOSMART and the precise irrigation timing with the hyperspectral spectroradiometer. The latter should be considered as a crucial and innovative step to estimate the plant water status and particularly the vegetation water potential and its components. These measurements represent important variables implicated in crop-water relationships and have potential in wider investigations related to irrigation scheduling and drought monitoring.

How do you use the ASD FieldSpec 4 Standard-Res Spectroradiometer?

The high performance of the FieldSpec 4 allows for the characterization of more detailed spectral features, including the minor changes in the shape or position of a peak, which helps to reveal hidden information that can explain the physical properties of a plant. In particular, the active dynamic changes in the equilibrium of plant water potential components (osmotic and turgor water potentials) that are frequently recognized in olive trees, can be evaluated through the analysis of the leaf spectral signature. This is a powerful tool to estimate the vegetation water status as well as the components of water potential. Moreover, the proposed methodology can be practically applied for studies related to plant-water relationships, irrigation scheduling, and drought monitoring.

Would you recommend the ASD FieldSpec 4?

Yes. The FieldSpec 4 is a very easy-to-use and powerful device that allows us to achieve reproducible results at a small (leaf) and large (canopy) scale. It is a very smart device for spectral acquisition at the leaf scale through the use of the contact probe and the ViewSpec software. The optimization phase of the radiation regime is very rapid and the quality of the spectra is excellent, with little noise or shift at the sensor's edge points. I recommend it for the high-accuracy spectral data. In my experience, I quantified very small variations in cell structural properties and water content of the olive leaf. Consequently, I enhanced my research quality and reached high-profile journals. The device allows water and energy cost-savings as a tool for water resource management.

What do you see for the future of agrohydrological research?

I can imagine that the next generation of farmers will be equipped with miniaturized spectroradiometers that, in synergy with an ATMOSMART, instruct a prompt and accurate irrigation decision support system.

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