Daniele Masseroni

An integrated, multisensor system for the continuous monitoring of water dynamics in rice fields under different irrigation regimes

The cultivation of rice, one of the most important staple crops worldwide, has very high water requirements. A variety of irrigation practices are applied, whose pros and cons, both in terms of water productivity and of their effects on the environment, are not completely understood yet. The continuous monitoring of irrigation and rainfall inputs, as well as of soil water dynamics, is a very important factor in the analysis of these practices. At the same time, however, it represents a challenging and costly task because of the complexity of the processes involved, of the difference in nature and magnitude of the driving variables and of the high variety of field conditions. In this paper, we present the prototype of an integrated, multisensor system for the continuous monitoring of water dynamics in rice fields under different irrigation regimes. The system consists of the following: (1) flow measurement devices for the monitoring of irrigation supply and tailwater drainage; (2) piezometers for groundwater level monitoring; (3) level gauges for monitoring the flooding depth; (4) multilevel tensiometers and moisture sensor clusters to monitor soil water status; (5) eddy covariance station for the estimation of evapotranspiration fluxes and (6) wireless transmission devices and software interface for data transfer, storage and control from remote computer. The system is modular and it is replicable in different field conditions. It was successfully applied over a 2-year period in three experimental plots in Northern Italy, each one with a different water management strategy. In the paper, we present information concerning the different instruments selected, their interconnections and their integration in a common remote control scheme. We also provide considerations and figures on the material and labour costs of the installation and management of the system.

Is soil water potential a reliable variable for irrigation scheduling in the case of Peach Orchards

Abstract Monitoring the crop water status of high-value crops such as fruit trees is generally performed through periodic measurements of physiological indicators on leaves or fruits using sophisticated instruments and complex procedures. These measurements are very often difficult to translate into irrigation advice. Soil water potential (SWP), however, is a basic soil water status variable that is correlated with plant water uptake, and it can easily be measured using sensors. Soil water potential can provide useful support for irrigation scheduling at the field scale, thus enhancing water savings in agricultural areas. In this work, we present the results of an experimental study conducted in the 2014 agricultural season on a peach orchard located in Lodi (Northern Italy). The purpose of this study was to evaluate the effects of an irrigation scheduling based on continuous SWP measurements collected at two soil depths (−15 and −35 cm) on the crop water status and the peach production relative to the farmer’s commonly adopted irrigation practice. To answer the question in the title, periodic measurements of physiological parameters such as leaf water potential, stomatal resistance (rs), transpiration (E), and crop water stress index were performed, along with monitoring of fruit size evolution and fruit sugar content at harvest. All of these variables were measured to assess the crop physiological state of the trees subjected to the two different irrigation treatments, with the final objective of determining whether the irrigation scheduling based on SWP measurements compromised the quality and quantity of produced peaches. Although obtained for only one agricultural season, the results showed that no considerably crop water stress occurred, even for the irrigation treatment based on SWP measurements. In particular, the most extreme values of leaf water potential, rs, E, and crop water stress index measured at midday were −2 MPa, 45 s m−1, 1.4 mm h−1 and 0.5, respectively, which are in good agreement with those observed in many studies for well-watered orchards in Mediterranean areas. In conclusion, we can stress that SWP monitoring can be considered to be a reliable alternative to the more costly and time-consuming physiological measurements for the irrigation scheduling of fruit crops such as peach orchards. This approach provides continuous information about the soil water status, thereby preventing plant water stress and reducing irrigation water consumption at the farm scale.

Validation of theoretical footprint models using experimental measurements of turbulent fluxes over maize fields in Po Valley

Representative source area of turbulent fluxes measured by eddy covariance stations is an important issue which has not yet been fully investigated. In particular, the validation of the analytical footprint models is generally based on the comparison with Lagrangian model predictions, while experimental results are not largely diffused in literature. In this work, spatial distribution of carbon dioxide, latent and sensible heat fluxes across two different maize fields in Po Valley, is used to validate two theoretical footprint models. Experiments are performed in two totally different scenarios at bare and vegetated soils using two eddy covariance systems: one fixed station which is located about in the middle of the field and a mobile station which is placed at various distances from the field edge to investigate the horizontal variation of the vertical scalar fluxes. The first objective of this work is to provide detailed information about the spatial distribution of turbulent fluxes across Po Valley characteristic fields at bare and vegetated soils, highlighting peculiarities and uniqueness. The second objective consists in the comparison between mobile measurements of carbon dioxide, latent and sensible heat fluxes and the predictions of two analytical footprint models widely used in literature. Contemporaneously, the latter objective will permit to understand what is the best footprint model which, under typical Po Valley atmospheric turbulent conditions, describes a representative source area compatible with the field dimensions and the turbulent flux distributions. The results show that both models are in good agreement with experimental measurements. The results also show that the spatial distribution of turbulent fluxes is strongly influenced by the presence of vegetation in the field. Moreover, the representative source area is different for different scalar fluxes. Another result is about 10:1 fetch-to-height obtained for both field situations.

Use of Spectral and Thermal Imaging Sensors to Monitor Crop Water and Nitrogen Status

High spatial and temporal resolution monitoring methods are the key to improve the efficiency in water and fertilizer input management. In this context, this work presents the set-up and the first results of a greenhouse experiment conducted on two crops with a different canopy geometry (rice and spinach) subjected to four nitrogen treatments. The experiment involves the acquisition of thermal, multispectral and hyperspectral images at three phenological stages for each crop. At each stage, spectral acquisitions are conducted on one-third of the pots, at good water conditions and, later on, at different times after interruption of irrigation. The total number of pots in the experiment is 72 (corresponding to 4 nitrogen levels x 2 crops x 3 phenological stages x 3 replicates). Just after the spectra acquisitions, non-destructive and destructive measurements of variables correlated with the crops nitrogen and water status are conducted. Multivariate regression analysis between the spectra features and measured variables will be used to identify predicting models for the estimation of crop water and nitrogen status. The most significant wavelengths for the detection of water and nitrogen stress could be the subject of a future experimentation in open field conditions using multispectral systems.