Browsing by Author "Wimalasiri, E. M"

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Open Access
Analyzing relationships between rainfall and paddy harvest using artificial neural network (ANN) approach: case studies from North-western and North-central provinces, Sri Lanka
(The Faculty of Agricultural Sciences of the Sabaragamuwa University of Sri Lanka, 2022-01-04) Ranasinghe, T; Rathnayake, U. S; Gunawardena, G; Wimalasiri, E. M
Purpose: Food and agriculture are frequently affected from on-going climate change. A significant percentage of annual harvest is lost due to extreme climatic conditions in different parts of the world. Sri Lanka is considered as a country which is vulnerable to climate change. Therefore, this research presents a detailed analysis to find out the non-linear relationships between the rainfall and paddy harvest in two major provinces of Sri Lanka. Research Method: North-central and North-western provinces as two major agricultural areas were selected for the study. Rainfall trends were identified using non-parametric Mann-Kendall and Sen’s slope estimator tests. The artificial neural network (ANN) approach was used to establish non-linear relationships between rainfall and paddy yield. Findings: There was no significant (p > 0.05) linear correlation between rainfall amount and the rainfed paddy yield in tested locations. However, no clear relationship between the rainfall and rain fed yield were found in the 14 predefined functions (polynomial, logarithmic, exponential and trigonometric) derived using ANN where the calculated coefficients of determination were less than 0.3. Research Limitations: Due to lack of other climate variables such as temperatures, a significant relationship was not observed in this study. Originality/value: We have shown that non-linear artificial neural network approach can be used to study the impact of climate on agricultural production in Sri Lanka.
Embargo
Effect of Three Types of Biochar in Cocopeat Medium on Shoot Cutting Production of Chrysanthemum
(Faculty of Humanities and Sciences,SLIIT, 2021-09-25) Kathriarachchi, A. S; Wimalasiri, E. M; Ampitiyawatta, A. D; Kumara, G. D. K; Weerasinghe, W. W. B. P. B
Biochar is a popular growing media amendment that increases fertilizer and water use efficiency, nutrient retention and crop productivity in floricultural crops. In Sri Lanka, cocopeat is used as the major growing medium for most of the floricultural crops. Therefore, the objective of this study was to incorporate biochar as a potential media amendment to improve the performances of plants through the enhancement of media properties. The performance of Chrysanthemum (Dendranthema grandiflora) was tested in amended media, as Chrysanthemum shoot cuttings is one of the most important floricultural products exported from Sri Lanka. The experiment was conducted with four treatments: B1 - 80% Coir dust+ 20% paddy husk biochar (v/v); B2 - 80% Coir dust+ 20% coconut shell biochar (v/v); B3 - 80% Coir dust+ 20% pine wood biochar (v/v) and C - 100% Coir dust (control). Incorporation of biochar significantly (p < 0.05) changes pH, electrical conductivity (EC) and water holding capacity (WHC) of the growing medium. Compared to the control, the time taken by Chrysanthemum shoots to reach standard size and quality did not show a significant (p > 0.05) difference in B1 while B2 and B3 showed significant (p < 0.05) differences. The number of shoots produced per plant three weeks after the first pinching and the post-harvest life and rooting performance was not significantly (p > 0.05) different among treatments. The incorporation of biochar into the coir dust growing medium for Chrysanthemum showed promising results which need to be assessed using other substrates and different mixing ratios.
Open Access
Evaluation of the Impact of Land Use Changes on Soil Erosion in the Tropical Maha Oya River Basin, Sri Lanka
(MDPI, 2023-01) Palliyaguru, C; Basnayake, V; Makumbura, R. K; Gunathilake, M. B; Muttil, N; Wimalasiri, E. M; Rathnayake, U
Soil degradation is a serious environmental issue in many regions of the world, and Sri Lanka is not an exception. Maha Oya River Basin (MORB) is one of the major river basins in tropical Sri Lanka, which suffers from regular soil erosion and degradation. The current study was designed to estimate the soil erosion associated with land use changes of the MORB. The Revised Universal Soil Loss Equation (RUSLE) was used in calculating the annual soil erosion rates, while the Geographic Information System (GIS) was used in mapping the spatial variations of the soil erosion hazard over a 30-year period. Thereafter, soil erosion hotspots in the MORB were also identified. The results of this study revealed that the mean average soil loss from the MORB has substantially increased from 2.81 t ha−1 yr−1 in 1989 to 3.21 t ha−1 yr−1 in 2021, which is an increment of about 14.23%. An extremely critical soil erosion-prone locations (average annual soil loss > 60 t ha−1 yr−1) map of the MORB was developed for the year 2021. The severity classes revealed that approximately 4.61% and 6.11% of the study area were in high to extremely high erosion hazard classes in 1989 and 2021, respectively. Based on the results, it was found that the extreme soil erosion occurs when forests and vegetation land are converted into agricultural and bare land/farmland. The spatial analysis further reveals that erosion-prone soil types, steep slope areas, and reduced forest/vegetation cover in hilly mountain areas contributed to the high soil erosion risk (16.56 to 91.01 t ha−1 yr−1) of the MORB. These high soil erosional areas should be prioritized according to the severity classes, and appropriate land use/land cover (LU/LC) management and water conservation practices should be implemented as recommended by this study to restore degraded lands.
Open Access
Modelling Potential Soil Erosion and Sediment Delivery Risk in Plantations of Sri Lanka
(MDPI, 2022-12-14) Karunaratne, A. S; Wimalasiri, E. M; Piyathilake, U; Gunatilake, S. K; Muttil, N; Rathnayake, U
The current trend in agricultural practices is expected to have a detrimental impact in terms of accelerating soil erosion. Assessment of the cumulative impact of various management strategies in a major plantation is a measure of the sustainably of soil resources. Thus, the current study aimed to develop the potential soil erosion map for a selected plantation (8734 ha in size) in tropical Sri Lanka using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) Sediment Delivery Ratio (SDR) model. The estimated mean annual soil loss rate of the selected plantation was 124.2 t ha−1 ranging from 0.1 to 6903.3 t ha−1. Out of the total extent, ~49.5% of the area belongs to the low soil erosion hazard category (0–5 t ha−1 year−1) while ~7.8% falls into very high (25–60 t ha−1 year−1) and ~1.3% into extremely high (60 < t ha−1 year−1) soil erosion hazard classes. The rainfall erosivity factor (R) for the entire study area is 364.5 ± 98.3 MJ mm ha−1 hr−1. Moreover, a relatively higher correlation was recorded between total soil loss and R factor (0.3) followed by C factor (0.2), P factor (0.2), LS factor (0.1), and K factor (<0.1). It is evident that rainfall plays a significant role in soil erosion in the study area. The findings of this study would help in formulating soil conservation measures in the plantation sector in Sri Lanka, which will contribute to the country’s meeting of the UN Sustainable Development Goals (SDGs).