Preparation of fertility assessment maps for some soils in Wasit Governorate using Kriging-cokriging technology

Abstract

The study was applied in Wasit Governorate at three sites: the first in Al-Ahrar District 
(45.5051995°E - 32.339372°N), the second in Al-Nu'maniyah District (45.5629394°E - 
32.336812°N), and the third in Al-Aziziyah District (45.061348°E - 32.911836°N). All required 
chemical and physical analyses for soil fertility assessment were performed on the study sites, as the 
soils in each site exhibited varying characteristics. The (GIS) and Kriging-cokriging technology were 
used to predict some soil fertility parameters and produce a fertility map for each region using the 
standard multiplication method using the following attributes: percentage of exchangeable sodium, 
electrical conductivity, soil reactivity, nitrogen, phosphorus, potassium, calcium carbonate, cation 
exchange capacity, organic matter, and texture. In addition, a database of soil attributes was built with 
minimal effort and cost. The results of the study indicated the presence of four soil classes in terms of 
fertility evaluation in the study areas, as the very fertile soil class did not appear, and the infertile soil 
class appeared once in the study areas. The fertile soil class F2 reached 40% in the Al-Ahrar region, 
20% in the Al-Nu’maniyah region, and 20% in the Al-Aziziyah region. This soil type is characterized 
by a clayey-silty texture, good organic matter, neutral pH, good NPK content, high CEC values, 
moderate lime content, low ESP content, and low salinity (EC). The medium-fertility soil type F3 
appeared at 40% in the Al-Ahrar area, 60% in the Al-Nu'maniyah area, and 33.33% in the Al
Aziziyah area. This type is characterized by a clayey-silty texture, moderate organic matter, neutral 
pH, good NPK content, high CEC values, moderate lime content, low ESP content, and low salinity 
(EC). The low-fertility soil type F4 reached 20% in the Al-Ahrar area, 20% in the Al-Nu'maniyah 
area, and 40% in the Al-Aziziyah area. This variety is characterized by the following features: it 
contains a clayey silt, clayey, and sandy mixture texture; relatively poor organic matter; neutral pH; 
good NPK content; average CEC values; average lime content; relatively high ESP content; and 
moderate salinity (Ec).