Characterizing Spatial Variability in Soil Water Content for Precision Irrigation Management

Alfonso De Lara,Raj Khosla,Louis Longchamps

doi:10.3390/agronomy8050059

Alfonso De Lara, Raj Khosla + Show 1 more

Open Access

https://doi.org/10.3390/agronomy8050059

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Abstract

Among one of the many challenges in implementing precision irrigation is to obtain an accurate characterization of the soil water content (SWC) across spatially variable fields along the crop growing season. The accuracy of characterizing SWC has been tested primarily on a small-scale and has received little attention from the scientific community at the field scale. Hence, the objective of this study was to assess the characterization of the spatial distribution of soil water content at the field scale by the apparent electrical conductivity (ECa). In evaluating the current aim, ECa survey was compared against repeated measurements of SWC at five depths using neutron probe. Results showed that mean SWC was different across ECa derived management zones, which indicates that on a macro-scale, soil ECa could effectively characterize the mean differences in SWC across management zones. Results also showed that deep ECa (0–150 cm) survey outperformed shallow survey (0–75 cm). Considering other soil properties, such as organic matter content and salt content, further improved the relationship between SWC and ECa.

Highlights

Fields exhibit spatial heterogeneity for several soil characteristics that influence soil water content (SWC), such as soil type and topography [1]
Available water-holding capacity (AWC) of soil is the maximum amount of water accessible to crops in the root zone [3]
As previously compare with the approach similar to that practiced by commercial retailers, three zones were mentioned, to compare with the approach similar to that practiced by commercial retailers, three zones calculated for each soil electrical conductivity (ECa) depth

Summary

Introduction

Fields exhibit spatial heterogeneity for several soil characteristics that influence soil water content (SWC), such as soil type and topography [1]. Common agricultural practice is to adjust the irrigation rate for the driest regions of the field, to ensure that no part of the field is under-irrigated [2] This practice results in the suboptimal utilization of water in many other parts of the field. A precise delineation of sub-field areas possessing similar characteristics, such as delineating site-specific management zones (SSMZ) [4,5], is key to precise irrigation management [6]. Variable Rate Irrigation (VRI) systems have made it technologically feasible to vary the amount of water applied across a field [1]. Thereby, VRI systems present an opportunity to improve water use efficiency by targeting optimal water rates needed within each zone

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Conclusion