TITLE:
Soil Salinity and Alkalinity Map Preparation Based on Spatial Analysis of GIS (Case Study: Tabriz Plain)
AUTHORS:
A. Farajnia, J. Yarahmadi
KEYWORDS:
GIS, Interpolation Techniques, Salinity and Alkalinity Map, Tabriz Plain
JOURNAL NAME:
Open Journal of Geology,
Vol.7 No.6,
June
7,
2017
ABSTRACT: Better
management of agricultural fields is related to valuable information which can
derived from soil salinity and alkalinity maps. These maps are considered as
one of the most important factors which restrict plant growth as well as
decline crops yield. The objective of this research was preparing of soil
salinity and alkalinity maps in Tabriz plain over 50,000 hectares based on
different techniques of spatial analysis in GIS software. For this mean, study
area was divided in 1500 × 1500 m2 grid
cells. Then, geographical coordinate of each grid recorded in UTM system. So,
they were transferred into GPS for navigating to the exact excavation location. After soil
sampling and transferring to the lab, their EC and PH were measured in
saturation extract of soil samples. So, spatial distribution of soil sampling
points was prepared in form of point map by GIS software. Generalization of
point information to surface was performed using different interpolation
algorithms and based on standards of Soil and Water Research Institute.
Accuracy of interpolated maps was evaluated due to the MAE and MBE values. The
results showed that the lowest observed error is related to the Spline method
and therefore, this
method was used for spatial modeling of salinity and alkalinity maps in the
intended area. The research findings demonstrated that from total of 50,000
hectares, only 3066 hectares were without salinity and alkalinity limitation (6.1%), 9066 hectares had low
salinity and alkalinity (18.1%); 17,772 hectares had average limitation for salinity and alkalinity (35.6%)
and the remaining 20,096
hectares had high and very high limitation for salinity and alkalinity.