TY  - BOOK
AU  - Ajin P Asok
AU  - Gladis R (Guide)
TI  - GIS approach for quality assessment and mapping of acid saline (KAIPAD) soils under agricultural land uses
U1  - 631.4 
PY  - 2022///
CY  - Vellayani
PB  - Department of Soil Science and Agricultural Chemistry, College of Agriculture
KW  - Soil Science and Agricultural Chemistry
N1  - MSc
N2  - The study entitled “GIS approach for quality assessment and mapping of acid 
saline (Kaipad) soils under agricultural land uses” was undertaken during 2019-21 to 
assess the soil quality and develop thematic maps on soil characters using GIS 
techniques. A survey was conducted in the Kaipad area (AEU-7) of Kannur, Kasargod 
and Kozhikode districts of Kerala and 126 representative georeferenced surface soil 
samples (0-20 cm) were collected from different agricultural land use systems 
prevailing in that area viz. rice, rice – shrimp, mangrove, coconut and fallow 
belonging to 10 soil series. Twenty five water samples were also collected and 
analysed for quality parameters.
The soil samples were assessed for various physical, chemical and biological 
properties and a weighted soil quality index was formulated based on a minimum data 
set (MDS) of parameters obtained by using principal component analysis (PCA). The 
PCA gave six principal components with eigen value greater than 1, which yielded 
nine parameters viz., pH, EC, organic carbon, available N, P, K, Mg, B and Zn.
Parameters in MDS were classified, scored and weights were assigned based on 
current soil characteristics, agricultural systems, and agro-climatic variables. Nutrient 
indices of organic carbon and available primary nutrients were also calculated. GIS 
maps were generated to depict the spatial variability in soil properties, quality and 
nutrient indices. 
Soil properties analysed were interpreted at panchayath and land use levels and 
correlation analysis were carried out between soil characteristics. Majority of the soils 
recorded a bulk density < 1.20 Mg m-3 (100%), particle density between 2.40 and 2.60 
Mg m-3 (44%), porosity between 50.0 and 70.0 per cent (86.5%), maximum water 
holding capacity between 30.0 and 50.0 per cent (52.4%) and MWD <1 mm (80.2%). 
Sandy clay loam was the predominant soil textural class in AEU 7. 
Majority of the soils (45.2%) showed extremely acid pH (<4.50). 81.7 per 
cent of samples had EC between 0.00 to 2.00 dS m-1. Available N was low in 94.4 per 
cent samples, available P medium in 41.3 per cent samples and available K low in 46 
per cent samples. Available Ca, Mg and B were deficient in 61.1 per cent, 100 per 
181
cent and 53.2 per cent samples respectively. Available S and cationic micronutrients 
like Fe, Mn, Cu and Zn were sufficient in most of the soils. Fe and Al toxicity were 
observed for 20.6 and 26 per cent of the soils respectively. Heavy metals (Pb, Cr, Cd 
and Ni) were below maximum permissible limit. Organic carbon was high in 57.1 per 
cent of samples, MBC between 100 and 300 µg g-1soil in 93.7 per cent samples and 
dehydrogenase activity between 1500 and 2500 µg TPF released g -1 soil 24 hr-1 in 
83.3 per cent samples. The soil quality was found to be medium in 88.2 per cent of the 
area. Nutrient indices were high for organic carbon, low for available N, and medium
for available P and low for available K in AEU 7. 
A significant variation among land uses were obtained for the soil parameters 
like soil moisture content, maximum water holding capacity, moisture content at field 
capacity, electrical conductivity, available N, Fe, B, Si, organic carbon and microbial 
biomass carbon whereas the other parameters did not vary significantly between land 
uses.
With regard to water quality, pH was found to be <6.5 in 52 per cent samples 
and EC was rated low (<2.5dS m-1) for 48 per cent of water samples and very high 
(22.5 – 50.0 dS m-1) for 28 per cent samples. SAR was <10 in all water samples, SSP
was between 40 and 60 per cent and RSC < 1.25 meq/L in most of the samples which 
was suitabile for irrigation. The concentration of heavy metals (Pb, Cr, Cd, Ni) was 
found to be above the critical limits in water samples. 
The acid saline soils of Kaipad (AEU 7) under different agricultural land uses 
are strongly to extremely acidic with high EC, deficiencies of N, K, Ca, Mg, B and Fe 
and Al toxicity which requires liming, addition of N, K, Ca, Mg and B to enhance 
productivity
ER  -