PGIA congress 2025

Permanent URI for this collectionhttps://ir.lib.pdn.ac.lk/handle/20.500.14444/7728

Browse

Now showing 1 - 20 of 22

Effect of dietary supplementation of yeast fractions (Safmannan®) on growth performance and nutrient digestibility in broiler chickens fed adulterated rice bran
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Samarakoon, S. M. R.; Vidanapathirana, V. S. A.; Jayawardana, B. C.; Karunaratne, N. D.; Munasinghe, V.; Weththasinghe, P.
This study investigated the effects of dietary supplementation of yeast fractions (Safmannan®) on growth performance and nutrient digestibility in broiler chickens fed rice bran adulterated with paddy husk. A total of 96 one-day-old Cobb 500 broiler chicks were randomly allocated to four treatment groups (n = 4 replicates, 6 birds per replicate) and fed one of four isonitrogenous and isoenergetic diets: T1 – corn-soybean-based control diet, T2 – control diet + 0.05% Safmannan®, T3 – control diet + paddy husk adulterated rice bran, and T4 – control diet + paddy husk adulterated rice bran + 0.05% Safmannan®. Growth performance was assessed weekly, and ileal nutrient digestibility was evaluated on day 33. At the end of the 35-day feeding period, carcass yield, breast muscle yield, and weights and lengths of digestive organs were measured. Dietary supplementation with 0.05% Safmannan® (T2) increased (P < 0.05) the final body weight (1691 g per bird), weight gain (1651 g per bird), and improved the feed conversion ratio (1.36 g/g). Inclusion of paddy husk adulterated rice bran (T3) reduced (P < 0.05) the growth performance, while the combination of Safmannan® with paddy husk (T4) showed partial recovery. Safmannan® supplementation also improved (P < 0.05) the carcass yield (72%), breast muscle percentage (32%), and digestive organ development when fed paddy husk adulterated diets. Apparent ileal dry matter digestibility was higher (P < 0.0001) in T2 (82%), with the lowest values observed in T3 (75%). Safmannan® supplementation enhanced growth performance and nutrient digestibility, while mitigating the adverse effects of adulterated rice bran in broiler diets.
Factors contributing to the adoption of recommended dairy management practices among small-scale dairy farmers in Sri Lanka
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Gunarathna, S.; Shah, J. A.; Buda, M.; Kaka, U.; Dissanayeke, U.
Sri Lanka continues to face a shortfall in dairy production, despite its high livestock production potential. Understanding the production environment of dairy farmers, is essential for enhancing productivity . Therefore, this study was designed to identify factors contributing to the adoption of recommended management practices. The study employed a cross-sectional research design and a quantitative research method. The study was conducted in the Central Province and utilized a questionnaire as the research instrument. A total of 393 small-scale dairy farmers were selected using a multistage sampling method. Adoption of Recommended Management Practices was assessed, based on breeding and reproductive management, feed and fodder management, and clean milk production. The conceptual model was developed by integrating the Unified Theory of Acceptance and Use of Technology, the Theory of Planned Behavior, and the data, information, knowledge, and wisdom framework. Data were collected on demographics of dairy farmers, knowledge, attitude, performance expectancy, effort expectancy, social influences, facilitation conditions, voluntariness, intention to adopt, and adoption of recommended management practices. Partial Least Squares Structural Equation Modeling was employed to analyze the structural relationships between multiple variables. Results revealed that knowledge, effort expectancy, social influence, facilitating conditions, voluntariness, and adoption intention significantly contribute to the adoption of recommended dairy management practices. These findings highlight the need of government interventions to enhance facilitating conditions and leverage social influence for improving national dairy productivity.
Paddy husk adulterated rice bran in broiler diets: impact on growth performance, nutrient digestibility and gut health
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Samarakoon, S. M. R.; Konthasinghe, K. H. M. N. B.; Weththasinghe, P.; Karunaratne, N. D.; Jayawardan, B. C.
This study evaluated the impact of dietary inclusion of paddy husk-adulterated rice bran on growth performance, nutrient digestibility, and the occurrence of intestinal lesions in broiler chicken. Five isoenergetic and isonitrogenous diets were formulated: a corn-soy-based control diet containing unadulterated rice bran and four diets containing rice bran adulterated with paddy husk at 3% (3PH), 5% (5PH), 8% (8PH) and 10% (10PH). One hundred and twenty Cobb 500, one-day old chicks were randomly fed with one of the five experimental diets (n=4 and 6 birds per replicate). The birds were provided with ad libitum water and feed for 35 days. Growth performance, relative organ weights and lengths, ileal dry matter digestibility and occurrence of small intestine lesions of the birds were assessed. Body weight gain (1483-1710 g per bird), feed intake (3137-3210 g per bird), and feed conversion ratio (1.86-2.19 g/g), showed no significant differences among dietary groups (P>0.05). Apparent ileal dry matter digestibility was also not significantly affected by the diets (P>0.05). Carcass yield and breast muscle yield remained unaffected, though gizzard and caecum weights were higher (P<0.05) in birds fed 8PH compared to those fed control diet, suggesting enhanced digestive function. Notably, birds fed 3PH reduced duodenal lesion odds (OR = 0.020, P<0.05), indicating a protective effect on gut integrity, while higher levels (5PH, 8PH and 10PH) showed no impact on intestinal lesions (P>0.05). In conclusion, rice bran adulterated with up to 10% paddy husk can be included in broiler diets without impairing growth performance or nutrient digestibility.
Distinguishing two morphologically similar Rhinacanthus species using Chloroplast barcoding regions
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Siyama, M.; Somaratne, Y.
Rhinacanthus flavovirens (Maha Anitta) belonging to the family Acanthaceae, is an endemic species to Sri Lanka. R. flavovirens is distributed in North central, Central, Southern and Western provinces in the country. R. flavovirens and R. nasutus possess a high level of morphological similarity, creating confusions in differentiating between the two species. DNA barcoding is a widely used molecular method for herbal plant identification and authentication, especially when morphological features are not sufficient. Chloroplast barcoding regions matK, rbcL and trnHpsbA have been used for this study. DNA was extracted and quantified using a Nanodrop spectrophotometer before amplification. The amplified fragment lengths for R. nasutus were 762 bp (matK), 369 bp (rbcL), and 333 bp (trnH-psbA), while those for R. flavovirens were 769 bp (matK), 370 bp (rbcL), and 364 bp (trnH-psbA). The Sanger sequencing showed that, among these three markers trnH-psbA showed the highest nucleotide variation (68.46%) whereas matK showed the lowest (1.3%). Pairwise genetic distance analysis showed that R. nasutus and R. flavovirens have closer genetic relatedness for matK region (0.0133) and higher divergence in trnH-psbA region (1.83). The MEME suite program identified a higher frequency of insertion/deletion events in trnH-psbA compared to matK and rbcL. The result of this study showed that DNA barcoding, particularly using variable region trnH-psbA, can effectively distinguish R. flavovirens from R. nasutus. Future studies incorporating whole chloroplast genome sequencing may provide enhanced resolution for species identification, authentication and phylogenetic analysis.
Economic and environmental viability of dairy cattle farming in areas under tea plantation: a case study in Gouravilla Grama Niladhari Division, Central Province, Sri Lanka
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Manojpraba, S.; Silva, G. L. L. P.
This study evaluated the economic profitability and environmental sustainability of dairy farming in tea plantation areas, focusing on 96 household dairy farms in the Gouravilla GN Division, representing the entire dairy-farming population in the area. Data were collected through a structured questionnaire and field observations, and analyzed using SPSS with descriptive statistics, Spearman rank-order correlation, Pearson correlation coefficients, and the Kruskal-Wallis test. Economic profitability was estimated using monthly average net income based on Wood’s equation-predicted milk yields, farmgate prices, and reported feed and variable costs. Profitability was mainly affected by poor breeding management, unstable milk pricing, and limited herd expansion opportunities. Poor breeding contributed to extended lactation lengths, prolonged calving intervals, reduced milk yields, fewer calves per cow lifetime, and reduced income. Unstable farmgate milk prices controlled by intermediaries’ further diminished profitability, as 83.4% of farmers received 140 LKR or less per litre of milk. Monthly average net income positively correlated with number of milking cows (r = 0.665, p < 0.01) and herd size (r = 0.320, p < 0.01). However, herd expansion was constrained by limited quality feed, insufficient financing, and land scarcity, with 28.1% of farmers lacking land for pasture. Low awareness of greenhouse gas emissions, manure handling, and animal welfare highlighted environmental sustainability gaps. This study further emphasizes strengthening breeding programs, ensuring fair milk pricing through formal collection, improving feeding based on local resources, and enhancing sustainability awareness are necessary to support profitable and environmentally responsible household dairy farming in tea plantation regions specially in upcountry
An investigation into the Floral biology of King-coconut and developing a protocol for artificial hand pollination
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Thilakarathne, M. G. O. S.; Perera, S. A. C. N.; Dissanayaka, H. D. M. A. C.
King coconut (KC) is an intermediate-type coconut form in Sri Lanka and a popular natural beverage. Despite its importance, floral biology remains largely unresearched. The objective of the present study was to investigate the key floral phases of KC in IL1a and IL3 agro-ecological regions (AERs) of Sri Lanka and to develop a protocol for artificial hand pollination. Seven palms aged 18-20 years were randomly selected per AER. All inflorescences emerging between December 2023 and December 2024 were recorded, totaling 74 in IL1a and 66 in IL3. The duration of the key floral phases of each inflorescence were recorded. A general linear model was employed to compare the two locations. The male phase began simultaneously with spathe opening of the inflorescence and lasted approximately 11-12 days in both regions. The female phase began 5-6 days after inflorescence opening and lasted for approximately seven days in both regions. A five to six-day overlap between the male and female phases was observed, indicating a predominant self-pollination breeding behavior in KC. Notably, the extended female phase over the male phase explains the presence of natural hybrids among progenies produced through open pollination. Based on these results, a stepwise hand-pollination protocol was proposed for KC, involving emasculation, bagging, artificial pollination, and subsequent bag removal. This research enhances knowledge of the reproductive biology of KC and offers guidelines for breeding programs, conservation efforts, and the establishment of seed gardens.
Anatomical, biochemical and physiological traits associated with drought tolerance in wild rice oryza rhizomatis vaughan
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Adhikari, A. M. D. M.; Abhayagunasekara, A. V. C.; Bandaranayake, P. C. G.
Water scarcity remains a key limitation in rice cultivation, underscoring the need for droughtresilient rice varieties. Oryza rhizomatis, an endemic wild rice species, represents a valuable genetic resource for enhancing drought tolerance in cultivated rice. This study investigated anatomical, biochemical, and physiological traits in two contrasting O. rhizomatis accessions, namely drought-tolerant accession-1 and drought-susceptible accession-21, collected from Puttalam and Hambantota, respectively. Sixty-five days after planting, plants were subjected to progressive drought stress in a completely randomized design until completely dry. Sets of plants were maintained as a control. Leaf rolling, a key drought-responsive indicator, was assessed using the Standard Evaluation System developed by International Rice Research Institute, and total phenolic content (TPC) was measured using Folin–Ciocalteu method. Leaf and floret anatomy was studied using a light microscope. Accession-21 exhibited a higher early-stage TPC (32.22±1.77 mg GAE/g) than accession-1, likely reflecting an early oxidative defense, whereas low TPC in accession-1 indicated the tendency of conserving energy for survival by limiting phenolic synthesis. Leaf rolling differentiated drought sensitivity, with delayed rolling (11%) in accession1 versus complete rolling (100%) in accession-21 after 29 days. Anatomically, accession-1 possessed larger bulliform cells (113.00±26.70 µm height; 215.67±49.07 µm width) and thicker lower epidermis (32.37±1.60 µm; P<0.05), reducing transpirational water loss. Although anther height did not differ significantly, accession-21 showed a taller stigma (5379.2±195.6 µm) than accession-1 (4415.1±227.9 µm), suggesting a potential reproductive advantage under stress. Overall, drought tolerance in O. rhizomatis is mainly associated with structural and physiological adaptations in accession-1, while accession-21 exhibits rapid phenolic accumulation and accelerated leaf rolling. These observations underscored the potential of the species for developing drought-tolerant rice.
Assessment of nutritional quality of lettuce as affected by Iron- and Zinc-enriched nutrient management techniques
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Bandara, R. M. B. A.; Eeswara, J. P.; Dissanayaka, D. M. S. B.
This study investigated the effect of Fe- and Zn-enriched nutrient management techniques on the fresh weight, and nutritional qualities, including nitrogen, phosphorus, ascorbic acid, antioxidants, and polyphenols of lettuce (Lactuca sativa) using Kjeldahl method, dry ashing technique using colorimetric method, visual titration method, DPPH assay and Folin-Ciocalteu assay, respectively. Furthermore, chlorophylls and carotenoids were analyzed by spectrophotometry. Fe and Zn were applied as FeSO4 and ZnSO4, respectively using three nutrient management techniques: nutripriming (soaking seeds in a nutrient solution), application to the growth medium, and foliar application. This study was conducted in a completely randomized design with three replicates in each treatment. The data were recorded at the physiological maturity stage. The results were subjected to ANOVA and mean separation using SPSS version 26. A significant (p<0.05) contribution of Fe was observed for the production of carotenoids through nutripriming. Furthermore, nutripriming enhanced the production of pigments such as chlorophylls and carotenoids in both Fe and Zn applications. A significant increase of ascorbic acid could be observed in foliar application of Fe whereas, it was from the growth medium application for Zn. Foliar application of ZnSO4 recorded a significant difference in antioxidant capacity of lettuce over other treatments, indicating the effectiveness of foliar applied Zn to increase antioxidant capacity of lettuce. In conclusion, nutripriming could improve chlorophylls and carotenoids while growth medium application and foliar application had positive influence on improving ascorbic acid content. A significant contribution of Zn was discovered for the improvement of antioxidants by foliar application.
Effect of reducing urea application on maize yield and stylo nodulation in a maize-stylo mixed-stand forage system
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Gammanpila, G. D. N. M.; Dandeniya, W. S.; Devindi, K. M.; Perera, K.A.K.S.; Edirisinghe, S.; Mahipala, M. B. P. K.
The influence of reduced urea application on biomass of hybrid fodder maize (Zea mays L. cv. Veera) yield and nodulation in stylo (Stylosanthes guianensis) in a maize-stylo mixed-stand was investigated. The experiment was conducted as a randomized complete block design with four urea levels; 425, 383, 340, and 0 kg/ha representing 100%, 90%, 80%, and 0% of the recommended rate. All treatments received 100 kg/ha TSP and 50 kg/ha MOP. In field experiment, stylo was sown (410,000 plants/ha) a month before establishment of maize (111,000 plants/ha). The same treatments were applied in a pot experiment. Forage sampling was conducted at the tasseling (VT) and dough (R4) stages of maize. In the field experiment, plant weight (PW) and dry matter yield (DMY) of maize were measured. In pots, stylo root nodules were counted. Regardless of fertilizer treatment, fodder maize reached VT and R4 stages at 8 and 10 weeks, respectively. At R4, maize recorded higher (P<0.05) PW (197±12-243±2 g/plant) and DMY (10.99±0.64-13.50±0.10 MT/ha) than at VT (105±5-128±8 g/plant; 5.83±0.30-7.12±0.42 MT/ha). Reduced urea application decreased (P<0.05) PW and DMY, but no significant difference (P>0.05) was observed between 100% and 90% rate at VT (125±3 vs. 128±8 g/plant) or R4 (243±2 vs. 217±8 g/plant). Correspondingly, DMY did not differ (P>0.05) at VT (6.97±0.16 vs. 7.12±0.42 MT/ha) and R4 (13.50±0.10 vs. 12.080.46 MT/ha). Stylo nodule number increased as urea decreased, with the highest (P<0.05) value at 0% urea (394.5±29.5 and 451.7±36.9 nodules/plant at VT and R4). Nodule numbers did not differ (P>0.05) between stages. A 10% reduction in urea is feasible without compromising maize fodder yield while enhancing stylo nodulation in a maize-stylo mixed-stand forage.
Characterizing physiochemical properties and nutrient leaching behavior of different coir-based substrate mixtures
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Kavinthini, A.; Vidana Gamage, D. N.
High production costs, limited resource availability, and the underutilization of byproducts such as short fiber have highlighted the need for more cost-effective coir substrate formulations in Sri Lanka. This study evaluated the physicochemical properties and nutrient leaching behavior of four factory-made coir-based substrate mixtures: A (100% coco peat), B (70% coco peat + 30% coco chips), C (80% coco peat + 20% short fiber), and D (60% coco peat + 30% coco chips + 10% short fiber). All mixtures exhibited bulk densities between 0.057 and 0.064 gcm-3, with substrate C showing the highest total porosity (40.79%) and highest water retention at 50 cm suction (0.66 cm³cm-3). Substrate B, with its coarse texture, had the lowest water retention (0.28 cm³cm-3) and the highest air-filled porosity (40.42%). Substrate C had the highest cation exchange capacity (CEC = 46.24 cmol⁺/kg) and an electrical conductivity (EC) of 1.63 dS/m, within acceptable limits (0.5–2.5 dS m⁻¹). A fertilizer-pulse leaching column experiment assessed nutrient breakthrough via nitrate and phosphate concentrations in successive leachate. Relative concentration (RC = C/C₀) vs. pore volumes (PVs) revealed retention patterns. The substrate B showed early breakthrough (0.10 PVs) and high RCs (0.90 for both NO₃⁻, PO₄³⁻), indicating poor nutrient retention. Whereas substrate C had delayed breakthrough (0.40 PVs NO₃⁻, 0.30 PVs PO₄³⁻) and lower RCs (0.70, 0.60 respectively), reflecting better nutrient retention from finer particles and higher CEC. Meanwhile, Substrate D outperformed B but was inferior to A and C. Incorporating 20% short fiber is promising, but further protected trials are needed to confirm agronomic and economic benefits.
Soil erosion assessment in tea lands of Nuwara Eliya, Sri Lanka, using the ¹³⁷Cs tracer technique
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Weerakkody, W. A. T. L.; Chandrapala, A. G.; Madhuroshika, H. A. D. I.; Dissanayake, W. M. I.; Mohotti, K. M.; Nissanka, S. P.
In Sri Lanka, tea is often grown in slopy lands, which increases the risk of soil erosion. This was to assess the erosion status of selected tea plantations during 2022-2023 in Labookellie, Weddamulla and Frotoft estates. For the reference site, nearby montane forest located in Labookellie was selected. Seventy-two soil samples were collected representing two canopy categories (well-grown VP tea and marginal seedling tea) and two slope classes (0-10% and 50 – 60%). At the reference site, cores were sectioned at 5 cm intervals up to 4 cm depth, while study site sampling comprised 40 cm bulk cores. 137Cs activity of soil was measured using a HPGe detector. Soil redistribution rates induced by water erosion were estimated by Mass Balance Model II. Forest area showed a lower soil erosion rate compared to the tea growing areas (p=0.002). Erosion rates were compared using an independent samples t-test, and correlations among parameters were assessed by Pearson correlation analysis. The 137Cs inventory for the forest site was 325 Bq/m2., and it was for tea lands ranged from 72-290Bq/m2 (mean=182.26 Bq/m-2). With increasing slope, erosion rates increased, and the slope category of 50-60% showed the highest erosion rate of 30.51 tons ha-1 y-1 with a sediment delivery ratio of 88% in Labookellie. Marginal tea lands had higher erosion (42.94 tons ha-1 y-1) compared to VP fields in Labookellie (p=0.002). Erosion rates showed negative correlations with organic matter (r=-0.7) and exchangeable K (r =-0.75) contents. Soil erosion in Nuwara Eliya tea lands is significantly influenced by slope and canopy cover.
Assessing the resistance levels of soil bacteria for Amoxicillin, Ciprofloxacin, Sulfamethoxazole and Trimethoprim
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Premarathne, H. P. S. R.; Dandeniya, W. S.; Kamburugoda, K. K. C. J.; Thaboshini, S.
Antibiotic resistance makes the control of infectious diseases a challenging task. Due to extensive use of animal-manure containing antibiotic residues and antibiotic-resistant bacteria (ARB), agricultural soils have become a main reservoir of antibiotic resistance genes. Investigating ARB populations in natural-ecosystems, using the established clinical breakpoint concentrations which have been developed considering pathogenic bacteria may overlook species important in antibiotic resistance. This study aimed to determine the threshold levels of amoxicillin (AMX), ciprofloxacin (CIP), sulfamethoxazole (SMT) and trimethoprim (TRM) to screen ARB from soil. Soils were collected at 0-10 cm depth from two intensively cultivated vegetable lands using animal-manure and a forest land. Bacteria were enumerated using pour plate technique on tryptic soy agar (TSA) medium spiked with each antibiotic separately at 0, 1, 5, 10 and 15 µg/mL in three replicates. Total bacterial population in cultivated soils (5.28±0.35 Log10 CFU/g) was significantly higher (p<0.05) than that in forest soil (3.21±0.16 Log10 CFU/g). Spiking TSA with 1 µg/mL of antibiotic, reduced bacterial abundance by 69% to 99%. Cultivated soils had significantly higher (p<0.05) abundance of ARB than in the forest soil. But relative abundance of ARB was higher in forest soil than in the cultivated soils. The abundance of ARB declined with increasing antibiotic concentration in TSA. In all three soils, relative abundance of ARB declined below 1% with 10 µg/mL concentration of AMX, SMT and TRM, and 1 µg/mL of CIP. Thus, these concentrations could be used as threshold levels to screen for respective ARB populations from soil. This knowledge can be used to monitor and prevent spread of antibiotic resistance in soils.
Identification and characterization of culturable Nitrogen fixing cyanobacteria from rice fields in the wet zone of Sri Lanka
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Guruge, K. C.; Jayasundara, J. M. P. C.; Balasooriya, B. L. W. K.
Cyanobacteria represent a highly diverse group of prokaryotes that thrive in aquatic ecosystems. Due to their nitrogen-fixing capabilities, cyanobacteria are considered as potential biofertilizers for paddy cultivation. This study aimed to isolate and identify culturable nitrogen fixing cyanobacteria in selected rice fields in the Wet Zone in Sri Lanka. Soil samples (0-10 cm) were collected from 13 paddy fields distributed in Gampaha, Colombo, Kegalle, Kalutara, and Galle districts and seven cyanobacterial species were isolated and characterized using morphological traits. Molecular analysis further confirmed their identities as four unicellular species (Chroococcus, Synechococcus, Aphanothece, Chroococcidiopsis) and three filamentous species (Leptolyngbya, Phormidium, Anabaena). Among them, Chroococcus and Phormidium emerged as the most widespread unicellular and filamentous species in the studied paddy fields. All isolates were successfully cultured and maintained in BG11 medium under controlled conditions (28 ± 2 °C, 100 rpm, 2,000 lx light intensity, and a 16:8 light-dark cycle). Laboratory assays confirmed their nitrogen-fixing potential. In addition, pairwise cross-streak method showed that all seven strains were mutually compatible. The findings highlight the diversity and abundance of cyanobacteria in the Wet Zone paddy soils, and results underscore the potential of the isolates as candidates to develop into biofertilizers through further research.
Biochar co-composting: a strategy for improving compost quality
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Delpitiya, D. G. P. S.; Dharmakeerthi, R. S.; Karunarathna, A. K.; Silva, N. R. N.
Use of biochar as a raw material in compost mixture has demonstrated numerous benefits during the composting process and to the end product. Changes in quality parameters in compost made by co-composting with poultry litter (PL) and PL biochar (PLB) were studied. Compost was made using the closed heap method. PLB was prepared by co-pyrolysing PL with (5% w/w) or without (0% w/w) Eppawala Rock Phosphate (ERP). Thus, four types of composts were produced: compost without biochar or PL (C), co-compost with 10% (w/w) PL (CPL), co-compost with 10% (w/w) PLB (CPLB), and co-compost with 10% (w/w) PLB co-pyrolysed with ERP (CPLB-ERP). Composts were characterized for chemical parameters in SLS 1635 using standard laboratory methods. Incorporation of PLB and PLB-ERP has significantly increased the total phosphorus in composts by approximately three-fold compared to C and CPL. Applying biochar enhanced the total potassium content by 33-47%, while also increasing the total Ca and Mg contents (p<0.05). There is no significant variation in Fe, Cu, Mn and Zn contents. Compared to CPL, a significant reduction in total nitrogen content was observed in CPLB and CPLB-ERP. The addition of ERP had led to an increase in total As content in CPLB-ERP, but still within the maximum permissible levels. Notably, biochar application reduced the total Pb content, while other heavy metals did not show significant differences among compost types. When considering quality parameters holistically, incorporation of PLB and PLB-ERP during the composting process enhances the quality of the compost produced.
Impacts of conversion of rubber to oil palm plantations on soil water dynamics in the low country wet zone of Sri Lanka
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Kularathna, K. M.; Vidana Gamage, D. N.
Conversion of land-use from rubber to oil palm may have implications for soil and water resources. This study investigated the impact of converting rubber plantations to oil palm on soil water storage (SWS) dynamics in the low-country wet zone of Sri Lanka. Volumetric soil water content of multiple soil depths (0-25, 25-50, 50-75, and 75-100 cm) was monitored in three replicates in adjacent 12-year-old oil palm and rubber plantations over December 2022 to March 2024 in Yatadolawatta estate, Mathugama. Soil water dynamics were assessed by comparing the SWS and change in SWS (∆SWS) at various depths within the 1 m of soil profile. The mean SWS was higher in rubber grown soils (271.56±21.67 mm) compared to oil palm (214.42±21.66 mm), which was attributed to significantly greater soil organic carbon (0–25 cm) and clay content (025, 25–50, 75–100 cm). A net increase in surface SWS, attributed to rainfall recharge, occurred in both land uses, while subsurface layers were depleted by root water uptake. Depletion in the 25-50 cm layer was significantly greater under oil palm, likely due to water uptake by its dense shallow root system. However, the extent of water depletion in the deeper layers (50-75 cm and 75-100 cm) and the 0-100 cm layer showed no significant difference. Conversion from rubber to oil palm did not lead to additional depletion of water in the deeper soil layers studied, indicating no significant impact on groundwater recharge potential. Further research across diverse soils and climates is recommended.
Development of a methodology to assess hydrological drought: a study in Kantale Irrigation Scheme, Sri Lanka
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Husna, M. S. F.; De Silva, R. P.; Dayawansa, N. D. K.
Hydrological drought occurs when there is a significant deficit in the availability of surface or groundwater resources. In river basins or watersheds with water storage facilities, reservoir water storage can be considered as an important indicator to assess the hydrological drought since it indicates the inflow, outflow and usage characteristics. This study introduces a refined methodology for assessment of hydrological drought and a distinct approach was employed to compute the magnitude of storage status of reservoir by making use of daily Reservoir Active Available Water Storage Percentage (RAAWSP). An assessment was conducted for the Kantale reservoir classified under major irrigation scheme in Trincomalee District in the Dry Zone of Sri Lanka. Reservoir daily storage, outflow and the nearby rainfall data were obtained from the Department of Irrigation, while Key Person Interviews (KPI) were conducted with irrigation officials to gain insights into the prevailing water management practices. Statistical analyses were carried out in Minitab 17 to test normality and examine the seasonal variability of the data series. The magnitude of storage status of reservoir was used to identify the hydrological drought seasons as validated against outflow and irrigation command area rainfall data. The estimated probabilities of hydrological drought occurrence during Maha and Yala seasons were 0.34 and 0.37, respectively for the assessment of 1995–2024 period and identified the presence of hidden hydrological drought, characterized by the availability of water in the reservoir that remain inaccessible for utilization for the beneficiaries due to the deficit of outflow. The study offers a new lens to understand the hydrological drought using management perspectives with the reservoir water balance.
Assessment of rainfall dynamics in the Hurulu Wewa irrigation scheme for climate-resilient water management
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Ariyarathne, W. M. M. G. C. J.; Dayawansa, N. D. K.; De Silva, R. P.
Understanding rainfall variability is vital for managing water resources and sustaining agriculture in the dry zone of Sri Lanka, where water scarcity poses serious challenges to the farming communities. This study examines rainfall variability, its impact on water availability and agriculture within the Hurulu Wewa Irrigation Division located in the dry zone of Sri Lanka, using a 30-year dataset (1995 to 2024) of daily rainfall from three selected stations, namely Kahatagasdigiliya, Kaudulla, and Nachchaduwa. The analysis focused on spatial and temporal rainfall patterns under the hypothesis that the second half of the study period would exhibit a greater prevalence of positive rainfall anomalies compared to the first half, thereby resulting in less intense drought conditions. The study area includes the major Hurulu Wewa reservoir, several medium and minor tanks, and a key paddy-growing region. Results show that 72% of the study years recorded annual rainfall below 1,750 mm. Among the three stations, Kaudulla recorded the highest long-term average annual rainfall (1,494 mm), while Kahatagasdigiliya recorded the lowest (1,154 mm). Seasonal rainfall follows a unimodal pattern, with the dominant Maha season (September-March) and the much drier Yala season (April-August), emphasizing the critical role of storage tanks in sustaining agriculture during the dry months. The Rainfall Anomaly Index identified 38% of the study years as drier; however, the rejected null hypothesis demonstrated less intense drought conditions leading to a greater occurrence of wetter or near normal years during the most recent 15 years. Furthermore, the analysis revealed a positive relationship between annual rainfall and the number of rainy days per year.
Seasonal CO₂ flux dynamics in tropical constructed Lakes: comparative insights from wet and dry zones of Sri Lanka
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Bandara, G. D. D. J.; Dayawansa, N. D. K.; De Silva, R. P.; Mowjood, M. I. M.
Tropical man-made freshwater systems are increasingly recognized as significant yet understudied contributors to atmospheric carbon dioxide (CO₂) emissions. It is hypothesized that CO₂ fluxes in reservoirs located in different climatic zones of Sri Lanka would exhibit distinct seasonal patterns due to contrasting environmental drivers. This study examined seasonal CO₂ flux dynamics in Thalangama Tank (wet zone) and Huruluwawa Tank (dry zone). Monthly six hour CO₂ flux measurements were conducted for six months using automated floating chambers. Simultaneously, monitoring of water quality and meteorological parameters performed. In Thalangama Tank, CO₂ flux remained consistently positive. Turbidity shows the strongest positive correlation (r = +0.53), indicating sediment resuspension, reduced solar radiation for aquatic photosynthesis and organic matter decomposition as dominant processes. One-way ANOVA revealed marginal seasonal variation (F = 2.42, p = 0.052), suggesting stable CO₂ emissions across months. In contrast, Huruluwawa Tank exhibited a significant seasonal shift from net CO₂ emission to uptake (F = 3.90, p = 0.008).Negative correlations were observed between CO₂ flux and wind speed (r = –0.56), turbidity (r = –0.53), and dissolved organic carbon (r = –0.35), implying enhanced mixing and primary productivity promoted CO₂ sequestration. These findings highlight distinct CO₂ flux patterns across climatic zones and highlight the necessity of zone-specific carbon assessments. Further, detailed investigations are essential to accurately identify the environmental controls governing CO₂ fluxes in tropical freshwater reservoirs, particularly in the context of climate change mitigation and ecosystem management.
Tragedy of centralization and the evolution of resource governance in village irrigation systems of Sri Lanka
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Abeyrathne, A. H. M. S. W. B.; Anuradha, J. M. P. N.; Pushpakumara, D. K. N. G.; Fujimura, M.; Punyawardena, B. V. R.; Ariyawanshe, I. D. K. S. D.
Colonial regimes across the Global South imposed centralized reforms that profoundly altered traditional systems of resource governance; Sri Lanka’s Village Irrigation Systems (VISs) were no exception. Using Systematic Literature Review methodology, this study reviewed 115 publications selected through rigorous screening and eligibility criteria to trace the evolution of VIS resource governance and climate adaptation rationales from the pre-colonial period to the present. The analysis reveals that centralized reforms, alongside commercialization trends and socio-economic dynamics, led to erode the integrated landscape governance attributes of VISs, i.e. self-governance with polycentric decision making, system-wide adaptation, multifunctionality, local institutions, and commons management, transforming them into paddy upland semi commercial mixed production systems. Climate adaptation, once embedded within the multifunctional village-tank-cascade landscape, was narrowed to agriculture. The reforms also dismantled communal property regimes, converting regulated commons into de facto “open access” resources, resulting widespread overuse and degradation of VIS catchment forests, later reclassified as state forests in the 1980s. This transformation, which was resulted by centralization generated governance challenges, and created multiple vulnerabilities. However, governance responses often involved further centralization, rather than restoring order. Despite Sri Lanka ratifying the United Nations Framework Convention on Climate Change in 1993, which introduced integrated approaches at implementation levels, the “tragedy of centralization” continues to constrain resilience. Hence, this study emphasizes the need to restore integrated landscape attributes embedded into the governance, but with adaptation to present social, institutional and market realities, with policy coherence. Long-term sustainability ultimately depends on the VIS’s capacity to remain adaptive and responsive to changing contexts.
Spatiotemporal linkages between habitat quality and water quality: a case study of Yan Oya, Sri Lanka
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Wickramasinghe, G. K. L.; Bandara, G. D. D. J.; Kumara, G. M. P.; Dayawansa, N. D. K.; Mowjood, M. I. M.
Evaluating the relationships between land-use practices, habitat quality, and water quality is crucial for sustainable river management. This study investigates how agricultural and forest land use influence the spatial and temporal dynamics of habitat quality and water quality in the Huruluwewa catchment of the Yan Oya basin. Field data were gathered monthly (January-June 2025) across 12 selected sampling locations in 50 km river reach from Habarana to Kahatagasdigiliya in Yan Oya, representing upstream–downstream gradients and varying landuse conditions. The water quality index was calculated based on pH, temperature, dissolved oxygen, turbidity, total dissolved solids, and electrical conductivity. Habitat assessments were conducted using the U.S. EPA’s Rapid Bioassessment Protocol. Land-use quantification was performed by developing a land-use/land-cover map. Correlation analysis revealed that increases in cultivated land were negatively correlated with the HQI (r = –0.635, p < 0.05) and WQI (r = –0.277, p < 0.05), reflecting sedimentation and reduced riparian cover from farming. Forest cover improved HQI (r = 0.406, p < 0.05) by stabilizing banks and enhancing habitat structure, although it showed no significant effect on WQI. Additionally, habitat and water quality index demonstrated a weak but statistically significant positive correlation (r =0.235, p<0.05) indicating that improvements in habitat quality were accompanied by slight increases in water quality. The six-month dataset provides preliminary evidence of interactions among land use, habitat integrity, and water quality, underscoring the importance of integrated watershed management strategies in agriculturally intensive landscapes. However, a more comprehensive understanding requires long-term monitoring and broader spatial coverage.

Browse

Recent Submissions