Variations in Soil Chemical Parameters of Long Term Sugarcane Growing Alfisols under Contrasting Cropping Conditions at Sevanagala, Sri Lanka

H.A.S Weerasinghe,A.N Jayakody,R.S Dharmakeerthi,G.P Gunaratne

doi:10.4038/tar.v31i2.8367

H.A.S Weerasinghe, A.N Jayakody + Show 2 more

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https://doi.org/10.4038/tar.v31i2.8367

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Abstract

This study was conducted to determine the variability of soil pH, macronutrients and Na contents in long term sugarcanegrowing Alfisols at Sevanagala, South-East of Sri Lanka. The study site included the entire sugarcane-growing area covering its contrasting cropping systems namely, irrigated and rain-fed cultivation on low humic gley (LHG) and reddish brown earth (RBE) soils, and adjacent undisturbed soils. The mean pH of the two soil types was significantly different and ranged from 4.5 to 9.3. Except some soils under rain-fed cultivation with a pH less than 5.5 in RBE soil and a pH greater than 7.5 in LHG soils, pH in all other soils favoured sugarcane growth. Plant available P content of soils were not significantly different among cropping conditions due to its wide variation. In both cropping systems and soil types there were areas with very low to nondetectable P levels. Exchangeable K content was significantly different between LHG and RBE soils with the latter having a mean concentration of 257 mg/ kg that is favourable for sugarcane cultivation. Though, the mean values are higher than the optimum range, there were K deficient patches in the studied area. Soil exchangeable Ca, Mg and Na contents were low in the study area but were significantly higher in LHG soils than in RBE soils contributing to alkalinity in the former soils especially under rain-fed conditions. The sugarcane-growing soils except LHG under rain-fed conditions showed chemical properties similar to undisturbed soils in the area highlighting their buffered nature despite long-term sugarcane cultivation. This study also emphasised the need for site-specific soil fertility management strategies for the Sevanagala sugarcane growing areas.

Highlights

Sugarcane (Saccharum officinarum L.) is a C4, annually harvested, sucrose-storing perennial true grass, belonging to the genus Saccharum (Arceneaux, 1965; Anna et al, 2014)
According to Dharmawardene (2004), 90-95 % of the sugarcane cultivation is dominated on Reddish Brown Earth (RBE) and less than 5 % on Low Humic Gley (LHG) soils
The RBE soils under both cropping systems and LHG soils under irrigated conditions have a pH around 6.5 which is favourable for sugarcane cultivation

Summary

Introduction

Sugarcane (Saccharum officinarum L.) is a C4, annually harvested, sucrose-storing perennial true grass, belonging to the genus Saccharum (Arceneaux, 1965; Anna et al, 2014). According to Mapa et al (2010), soils in Sevanagala sugarcane-growing area fall into the Alfisol soil order, and mapped as Walawe Mahagal Ara - Ketagal Ara - Sevanagala association. The Walawe series is Typic Haplustalfs (FAO classification: Rhodic Endoentric Luvisols) and Mahagal Ara series is Oxyaquic Hapludalfs (FAO classification: Ochric Luvisols). Both of these series belongs to great soil group of Reddish Brown Earth (RBE) soils (Alwis and Panabokke, 1972). The Ketagal Ara series is a Low Humic Gley (LHG) soil and according to soil taxonomy it is a Typic Endoaqualfs (FAO classification: Gleyic Cutamic Hyperentric Luvisols). The soil under Sevanagala series is Solodized solonetz, taxonomically referred to as Typic Natraqualfs (FAO classification: Gleyic Solanchaks). Cultivation under Solodized solonetz soil is negligible due to its saline and/or sodic condition and poorly drained nature

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