SOIL ORGANIC MATTER AND WET AGGREGATE STABILITY IN TSUNAMI AFFECTED SOILS IN HAMBANTOTA DISTRICT, SOUTHERN SRI LANKA

B. Walpola; A. Somaratne; S. Subasinghe; A. A. Kumara; M. De S. Liyanage; R. Senaratne; L. D. Martin

doi:10.31357/fesympo.v0i0.1247

Authors

B. Walpola Department of Agriculture Chemistry, Faculty of Agriculture, University of Ruhuna,
A. Somaratne Department of Crop Science, Faculty of Agriculture, University of Ruhuna,
S. Subasinghe Department of Crop Science, Faculty of Agriculture, University of Ruhuna,
A. A. Kumara Department of Crop Science, Faculty of Agriculture, University of Ruhuna,
M. De S. Liyanage Department of Crop Science, Faculty of Agriculture, University of Ruhuna,
R. Senaratne Department of Crop Science, Faculty of Agriculture, University of Ruhuna,
L. D. Martin Muresk Institute of Agriculture, Curtain University of Technology, WA, Australia

DOI:

https://doi.org/10.31357/fesympo.v0i0.1247

Abstract

Seawater intrusion occurred due the recent tsunami disaster badly affected onagricultural lands causing failure in crop production. Apart from elevatingsalinity level, addition of sodium ion with sea water creates dispersion of soilparticles, destroying it's aggregates or the structure, prompting immediateneed of rehabilitating the affected lands in order to sustain the productivity.Therefore the objective of the present study was to assess the impact oftsunami on Soil Organic Matter (SOM) and wet aggregate stability of theaffected soils in Hambantota district.

Random soil samples were drawn from top 15cm soil depth, two weeks aftertsunami and analysed for SOM, wet aggregate stability (measured as MeanWeight Diameter or MWD) and aggregate distribution. Soil samples takenfrom a nearest unaffected field on the same soil type were used as thereference to compare the affected and unaffected soils.

The average SOM contents of 0.27% and 1.06% respectively for the tsunamiaffectedsoils and the reference unaffected soil revealed a greater reduction ofSOM as a consequence of seawater intrusion. It could be explained theresults that removal of SOM by means of soil erosion and/or deposition oflarge amounts of sand dunes. According to the results, the highest MWD wasobserved from unaffected soil, while the lowest values found in affectedsoils. Furthermore, it can be seen a positive correlation between SOM andwet aggregate stability indicating an urgent need to improve soil managementpractices that increase SOM levels, and as a result, increase the soil aggregatestability in order to ensure sustained crop production in affected soils inHambantota district.