Predicting the spatial distribution of water applied by subsurface drip in clay soil¹

Predição da distribuição espacial da água aplicada por gotejamento subsuperficial em solo argiloso

ABSTRACT

In subsurface drip irrigation systems, knowledge of the three-dimensional advancement of water in the soil is essential for selecting emitter spacing and installation depth. This research aimed to develop and test different mathematical models to estimate water distribution in the soil under subsurface drip irrigation. The experiment was set up in a completely randomized design with four replicates. The experimental arrangement was of split-plot in time, with different dripper installation depths in the plots (0, 5, 10, 15, 20, 25, and 30 cm) and in the subplots irrigation application times (0, 60, 120, 180, and 240 min). Three models (SLIDE 6.0, polynomial regression, and SPSS 2.0) were constructed to estimate the water distribution in the soil profile. All models showed statistical indexes within acceptable ranges. In comparison, the model generated in the numerical software SLIDE 6.0 was the one that presented the best performance, followed by SPSS 2.0 and polynomial regression. The generated models were efficient and simple, producing good results in predicting the water distribution in the soil profile under the studied conditions.

Key words:
soil moisture; buried drip irrigation; localized irrigation; irrigation modeling

HIGHLIGHTS:

The tested models are suitable for simulating water spatial distribution by drippers operating at depth in soil columns.

The installation depths of the drippers do not affect the estimation of soil moisture by the mod-els evaluated.

SLIDE 6.0 outperformed SPSS 2.0 and polynomial regression models for simulating soil water dis-tribution.