Abstract:
The knowledge on the accumulation of essential and toxic trace elements in rice
growing soils is crucial for sustainable soil nutrient management and rice crop
production. The aim of the present study was to investigate the total concentration
of essential and toxic trace elements and their relationships in Sri Lankan paddy
soils. Two hundred soil samples were collected representing three climatic zones
and seventeen soil types using stratified random sampling approach. The total
elements concentrations were measured using X-ray florescence (XRF) analyzer.
The minimum and maximum total element concentrations were determined using
descriptive statistics. Relationships among total element concentrations were
tested using correlation and principle component (PC) analyses, and the
concentrations of elements among climatic zones and soil types were compared
using ANOVA. The highest mean total element concentration in soil samples was
recoded in Fe which ranged from 220 to 71,994 mg kg-1 followed by K (316-31, 153
mg kg-1) and Ca (44-19, 436 mg kg-1). The lowest mean total concentrations were
observed in As and Mo (<3 mg kg-1). Soil Fe concentration was positively correlated
with Mn, Cu, Zn, As and Pb (r > 0.5, p<0.05). Among the climatic zones, Wet Zone
soils (WZ) contained higher concentrations of Fe, Zn, As and Pb whereas Dry Zone
and Intermediate Zone soils had higher concentrations of Ca and K compared to WZ
soils. When compare different soils categories, Bog and Half-Bog soils and Red Yellow Podzolic soils had higher Fe, Zn, As and Pb concentrations whereas lower
concentration of Ca and K were observed. The highest Mn concentration was in
Grumusols while Cu concentration was relatively uniform in all soil types tested.
Elements concentrations and their relationships studied in this research would be
important in sustainable nutrient management in Sri Lankan rice fields.
