Assessing Salt Accumulation in the Root Zone of Tomato Plant Through Using Ordinary Kriging Interpolation Technique Under Deficit Irrigation Regime

Year 2019, Special Issue: 1st Int. Congress on Biosystems Engineering 2019, 120 - 127, 27.12.2019

Amal Ghannem , İmed Ben Aissa , Mahmut Cetin , Rajouene Majdoub

Abstract

Aims: Deficit irrigation might be a remedy to increase water use
efficiency in water scarce areas albeit it may cause to: a) increase salt
accumulation in the root-zone, b) decrease crop yield. Therefore, monitoring
and assessment of salt accumulation in the root-zone is necessary in deficit
irrigation practices. Primary objectives of this work were to: a) assess salt accumulation in the
root-zone of tomato crop irrigated with conventional deficit irrigation (DI-50)
through using ordinary kriging interpolation technique, and b) compare it with full irrigation (FI)
treatment.

Methods
and Results: To this
end, soil electrical conductivity (EC in dS m^-1) measurements
were conducted under emitters, between emitters and plant, and under plant on
right and left side of root-zone by using an EC probe. In order to assess
spatial and temporal changes of salt accumulation in the root-zone of tomato
crop, EC lectures were done: a) at the beginning crop growth stage, b) in the
middle, and c) at the end of growing season. In order to generate salinity maps
in the root-zone, geostatistical interpolation techniques have been utilized.
Geostatistical analysis has been realized by using “Jeostat-2017” software. Geostatistical analysis results indicated
that the most suitable theoretical semivariogram model to the experimental
semivariogram was Gaussian and/or Spherical model. Cross validation analysis
revealed that kriging interpolation errors were fitted to the normal
distribution, indicating that theoretical semivariogram model and its
parameters as well as kriging search parameters are representative for the
study site. Kriging errors helped us to evaluate efficiency of sampling design
for salinity assessment. The kriging estimation maps for EC showed spatial and
temporal salt accumulation process in the root-zone of tomato crop.

Conclusions: In this regard, results showed that salt accumulation was
concentrated in the root-zone just beneath the plant. This finding can be
explained by the heavy texture of soil, which obstructs the leaching operation
also by the high root density of tomato under this profile. Soil salinity maps
reveal that salt accumulation in the root-zone gets more and more as the
growing stage progress.

Significance
and Impact of the Study: Deficit
irrigation treatment reduce the amount of total salt accumulated in the root
zone compared with the full irrigation treatment due to the fact that the
amount of water applied with deficit irrigation is half of the full treatment,
hence salt accumulation

Keywords

Deficit irrigation, salt accumulation, electrical conductivity, ordinary kriging, semivariogram, sampling scheme

Supporting Institution

Erasmus+ mobility program (University of Sousse- Cukurova University)

Project Number

Project No: FYL-2019-11771

Thanks

The financial support was provided by Erasmus+ mobility program. Authors would like to acknowledge to the Department of Scientific Research Projects of Cukurova University Rectorate for the financial support (Project No: FYL-2019-11771) to attend to the conference.

Assessing Salt Accumulation in the Root Zone of Tomato Plant Through Using Ordinary Kriging Interpolation Technique Under Deficit Irrigation Regime

Abstract

Aims: Deficit irrigation might be a remedy to increase water use
efficiency in water scarce areas albeit it may cause to: a) increase salt
accumulation in the root-zone, b) decrease crop yield. Therefore, monitoring
and assessment of salt accumulation in the root-zone is necessary in deficit
irrigation practices. Primary objectives of this work were to: a) assess salt accumulation in the
root-zone of tomato crop irrigated with conventional deficit irrigation (DI-50)
through using ordinary kriging interpolation technique, and b) compare it with full irrigation (FI)
treatment.

Methods
and Results: To this
end, soil electrical conductivity (EC in dS m^-1) measurements
were conducted under emitters, between emitters and plant, and under plant on
right and left side of root-zone by using an EC probe. In order to assess
spatial and temporal changes of salt accumulation in the root-zone of tomato
crop, EC lectures were done: a) at the beginning crop growth stage, b) in the
middle, and c) at the end of growing season. In order to generate salinity maps
in the root-zone, geostatistical interpolation techniques have been utilized.
Geostatistical analysis has been realized by using “Jeostat-2017” software. Geostatistical analysis results indicated
that the most suitable theoretical semivariogram model to the experimental
semivariogram was Gaussian and/or Spherical model. Cross validation analysis
revealed that kriging interpolation errors were fitted to the normal
distribution, indicating that theoretical semivariogram model and its
parameters as well as kriging search parameters are representative for the
study site. Kriging errors helped us to evaluate efficiency of sampling design
for salinity assessment. The kriging estimation maps for EC showed spatial and
temporal salt accumulation process in the root-zone of tomato crop.

Conclusions: In this regard, results showed that salt accumulation was
concentrated in the root-zone just beneath the plant. This finding can be
explained by the heavy texture of soil, which obstructs the leaching operation
also by the high root density of tomato under this profile. Soil salinity maps
reveal that salt accumulation in the root-zone gets more and more as the
growing stage progress.

Significance
and Impact of the Study: Deficit
irrigation treatment reduce the amount of total salt accumulated in the root
zone compared with the full irrigation treatment due to the fact that the
amount of water applied with deficit irrigation is half of the full treatment,
hence salt accumulation.

Keywords

Deficit irrigation, salt accumulation, electrical conductivity, ordinary kriging, semivariogram, sampling scheme

Project Number

Project No: FYL-2019-11771

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