Predicting soil EC e based on values of EC 1:2.5 as an indicator of soil salinity at Magozi irrigation scheme, Iringa, Tanzania
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Date
2021
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An International Journal of Basic and Applied Research
Abstract
Soil salinity is one of the limitations to sustainable production of rice and other crops in
many irrigation schemes in Tanzania. Soil salinity can be assessed from electrical conductivity
(EC) measurements. Most soil laboratories in Tanzania appraise soil salinity from measurements
of electrical conductivity of 1:2.5 soil:water suspensions (EC 1:2.5 ) by virtue of their simplicity.
However, the influence of soil salinity on plant growth is mainly based on electrical conductivity
of saturated paste extract (EC e ), so it is necessary to convert EC 1:2.5 to EC e in order to assess plant
response to salinity. This study was conducted at Magozi Irrigation Scheme in Iringa Region,
Tanzania to establish regression model for predicting EC e from EC 1:2.5 values. A total of 60 soil
samples (45 samples for model training and 15 samples for model validation) were collected and
analyzed for soil EC 1:2.5 , EC e and soil texture. Results showed that EC 1:2.5 ranged from 0.1 to 4.2 dS
m -1 with a mean value of 0.71 dS m -1 . EC e obtained ranged from 0.3 (non-saline) to 12 dS m -1 (very
saline) with a mean of 2.4 dS m -1 (slightly saline). In order of dominance, soil textural classes were
sandy clay loam, clay, sandy clay, sandy loam and clay loam. Strong linear relationships between
EC e and EC 1:2.5 were observed in the developed linear regression equations. After validation, the
study selected equation ECe = 3.4954*EC 1:2.5 with R 2 of 0.956 for combined soil textures to be used
for prediction of EC e from EC 1:2.5 at Magozi Irrigation Scheme. This model can be tested for its
applicability to other similar soils in Tanzania in further studies.
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Journal article
Keywords
Soil salinity, EC e, EC 1:2.5, Soil salinity prediction, Magozi irrigation scheme