Water & Land Experimental Fields

Due to the intrinsic diversity of soils and the need to collect an appropriate number of field observations, which are particularly useful for the parallel research trials run at the Soil Hydrology Laboratory of IAMB, a specific device for the field determination of hydrologic parameters in porous media has been developed, as shown in the figure below.

The apparatus uses a double-comb network of dripping lines, constituted each by three overlapping lines supporting 2.5 m spaced self-compensating drippers with a flow rate ranging between 2 and 12 l/h. The parallel monitoring of water contents and of soil water pressure potentials will be ensured through TDR probes and tensiometers, respectively.

Soil hydrological properties will be estimated from three-dimensional flow fields under the drippers in different monitoring sites.

The experimental trials run at CIHEAM Bari are described below.

Trial 1: salinity trials on three transects irrigated with saline water

The study area covers 462m2 and includes three transects of 30mx4.2m.

Trial 2: trial on salinity induced by salt and water stress

Unlike empirical models, inversion models are physically based and are more reliable in returning specific electrical conductivity at different depths.

The experimentation has proposed an innovative approach in the study of the mechanisms influencing water and/or salt stress in the plant. The study is directed not only to survey each single site but is aimed to identify the spatial scale that determines plant response to salinity.

Trial 3: Irrigation uniformity trials

Plant water storage is mainly related to the soil hydrological properties. Therefore, defining irrigation uniformity on the surface is not sufficient to determine the soil available water. The uniformity determined on the surface takes into account only the hydraulic properties of the irrigation system (e.g. flow rate, pressure). The trial is intended to identify an indicator quantifying soil uniformity. On this basis, three experimental trials have been set up and are shortly described below.

Trial 4: Sprinkler irrigation uniformity trial

A four-sprinkler system has been set up over an area of 16mx16m (256m2). Three TDR probes 15cm long have been installed at three different depths (10, 20 and 30cm) every 3m covering the entire study area. Irrigation uniformity has been determined at three different pressures (4, 3 and 2 bars). The objective of the trial is to assess surface uniformity at three different pressures and determine soil uniformity indicators (e.g. Application Efficiency, AE, Soil Water Storage Efficiency, SWE).

Trial 5: Drip irrigation uniformity trial

A uniformity trial is conducted over an area of 150m2. Drippers are placed 1m apart from each other on three rows corresponding to three different flow rates (2, 4, 6 l/h). Irrigation is managed applying conventional water to bring the soil moisture profile to field capacity. Soil hydraulic parameters are monitored by means of a TDR probe of 25cm inserted vertically on the soil surface to monitor the temporal evolution of water contents.

In the case of drip irrigation, the distribution uniformity indicator enables water distribution quantification only on the surface and does not take into account infiltration and water redistribution processes in the soil. The objective of the trial is to identify a viable indicator to quantify soil available moisture taking into account that a high water supply does not always result in higher available moisture and viceversa.

Trial 6: Irrigation trial with saline water

The trial is run to define the dynamics regulating salt distribution in the wetted area. The trial covers an area of 150m2 (15mx10m) and is subdivided into 4 experimental plots, as shown below. Each treatment has 5 rows and drippers are spaced at 1m. Each plot is irrigated using different flow rates equal to 2,4,8 and 12l/h, respectively. The aim of the trial is to assess the effect of dripper flow rates on water and salt distribution in the wetted area.

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