Research and Publication

Publication in refereed journals


  • Ratnayake, R.R., Roshanthan, T., Gnanavelrajah , N and Karunaratne, S. B (2019). Organic Carbon Fractions, Aggregate Stability, and Available Nutrients in Soil and Their Interrelationships in Tropical Cropping Systems: A Case Study. Eurasian Soil Science, Vol. 52 (12: 1542–1554


  • Senthuran, S., Balasooriya, B.L.W.K., Arasakesary, S.J and Gnanavelrajah,N (2019).Effect of Seaweed Extract (Kappaphycus alvarezii) on the Growth, Yield and Nutrient uptake of Leafy Vegetable Amaranthus polygamous, Short communication. Tropical Agricultural Research Vol. 30 (3): 81–88


  • Mapa, R.B., Gowthamy, P., Dassanayake, A.R., Gnanavelrajah, N. And Kulasiri, A.H.(2018). Characterization of soil physical properties of calcic red latasols and calcic yellow latasols in jafna peninsula of sri lanka and their applicabaility to agriculture. J.Soil Sci.Soc Sri Lanka, Vol. 25, 2018


  • Ratnayake, R.R., Karunaratne, S.B., Lessels, J.S., Yogenthiran, N., Rajapaksha, R.P.S.K. and Gnanavelrajah, N., 2016. Digital soil mapping of organic carbon concentration in paddy growing soils of Northern Sri Lanka. Geoderma Regional 7:167-176


  • Ratnayake, R. R., T. Kugendren, and Gnanavelrajah, N (2014).Changes in soil carbon stocks under different agricultural management practices in North Sri Lanka.Journal of the National Science Foundation of Sri Lanka 42.1: 37-44.


  • Sundaralingam, T., and Gnanavelrajah, N (2014).Phytoremediation Potential of Selected Plants for Nitrate and Phosphorus from Ground Water. International Journal of Phytoremediation 16.(3) : 275-284.


  • Rajendra P. Shrestha , Dietrich Schmidt-Vogt , Nalina Gnanavelrajah, (2010) Relating plant diversity to biomass and soil erosion in a cultivated landscape of the eastern seaboard region of Thailand. Applied Geography doi:10.1016/j.apgeog.2010.01.005


  • Sivasakthy, K and Gnanavelrajah, N(2010). Effect of neem (Azadirachtaindica) leaf on nitrification and selected properties of soil amended with different sources of nitrogen. Journal of Science and Management. 2: 26 - 32


  • Prasanthi, B., Loganathan, P and Gnanavelrajah, N (2010) Nitrate leaching column study in vegetable growing soil amended with gliricidia in Vavuniya district. Journal of Science and Management.,2: 12-17.


  • Rajendra P. Shrestha and Nalina Gnanavelrajah (2009).Assessing Biophysical and Socioeconomic Condition for Watershed Management: Case of KhlongYai Watershed, Eastern Thailand. GMSARN International Journal 3 (4): 145 – 150.


  • Gnanavelrajah, N., Shrestha, P.P., Schmidt-vogt, D and Samarakoon, L (2008) Carbon stock assessment and soil carbon management in Agricultural land-uses in Thailand. Land Degradation & Development 19 (3): 242 – 256


  • Gnanavelrajah,N and Kumaragamage, D. (1999) Nitrogen leaching and plant response to nitrogen fertilizers as influenced by application of Neem (Azadirachtaindica A. juss) materials. Tropical Agricultural Research. (11): 30 – 42


  • Gnanavelrajah,N and Kumaragamage, D. (1998) Effect of Neem (Azadirachtaindica A. juss) materials on nitrification of applied urea in three selected soils of SriLanka. Tropical Agricultural Research. (10) : 61 – 73


  • Mohanadas, S and Gnanavelrajah, N (1994) Effect of different organic manures in combination with inorganic fertilizers on growth and yield of rice. Journal of Science (9): 23 – 28


Selected Publications in Conferences/workshops

  • Kasthuri,J and Gnanavelrajah, N. (2021).Potential of selected underutilized organic residues and Azolla, Spirulina grown in wastewater as plant nutrient sources. Proceedings of International Symposium on Agriculture and Environment (ISAE 2021). Faculty of Agriculture, University of Ruhuna, Sri Lanka, 7th May 2021, pp.32.

  • Kasthuri,J and Gnanavelrajah, N. (2021). Different Organic Sources as Germination Enhancers of Selected Seeds and as Components of Fertilizer Formulation for a Test Crop. Proceedings of 4th International Research Conference of uva Wellasa University (IRCUWU 2021). University of Uva Wellasa, Sri Lanka, 1st -2nd July 2021,pp.10.

  • Thamilini, R., Gnanavelrajah, N., Arasakesary, S.J and Amirthalojanan, A. 2020. An innovative liquid fertilizer to promote growth and yield responses of tomato (Lycopersicon esculentum Mill). Proceedings of the 9th YSF Symposium held on 13 November 2020. 197 – 201.

  • Kalaivani, S and Gnanavelrajah, N. 2020. Formulation of Organic Liquid Fertilizers and their Effects onGermination of Selected Seeds and Growth and Yield of Chilli (Capsicum frutescens L.). 6th International Conference on Dry Zone Agriculture (ICDA 2020) held on 3rd - 4th December 2020 at the Faculty of agriculture, University of Jaffna, Sri Lanka. pp.85.

  • Koswaththa, K.R.H.D., Dissanayaka, P.S., Gnanavelrajah, N and Abhiramy, K. 2020. Isolation and Identification of Efficient Phosphate Solubilizing Bacteria from Soil and Its Effect on Growth and Yield of Zea mays. 6th International Conference on Dry Zone Agriculture (ICDA 2020) held on 3rd - 4th December 2020 at the Faculty of agriculture, University of Jaffna, Sri Lanka. pp.88.

  • Chathuranga, D.M.B.A., Paranavithana, T.M., Gnanavelrajah, N and Ratnayake R.R. 2020. Spatial Variability of Soil Carbon and Its Relationship with Nutrient Availability in Paddy Soils of Trincomalee District, Sri Lanka. 6th International Conference on Dry Zone Agriculture (ICDA 2020) held on 3rd - 4th December 2020 at the Faculty of agriculture, University of Jaffna, Sri Lanka. pp.90.

  • Thamilini,R., Gnanavelrajah, N., Arasakesary, S.J and Amirthalojanan, A (2020). Assessing the nutrients use efficiency of Tomato (Lycopersicon esculentum.Mill) with different organic and inorganic fertilizer treatments. Proceedings of the Annual sessions of Jaffna Science association held on 23 October 2020.

  • Kasthuri, J., Abhiramy, K. and Gnanavelrajah, N. 2020. Potential to Grow Organic Nitrogen Sources Spirulina and Azolla in Different Wastewater. International Poster Presentation Competition (IPPC) 2020. Organized by NYAB, INYAS, SLAYS and TYSA held in September – October 2020.

  • Nareshkumar,S Gnanavelrajah, N and Raveendran, S (2019). “Assessment of Palmyrah Palm Distribution and Density in East and South East of Valikamam Region in Jaffna Peninsula Using Very High Resolution Satellite Images” International Symposium on Agriculture-2019 (ISA-2019) Faculty of Agriculture, Eastern University, Sri Lanka., held on 9th January 2019


  • Thurairajah, A., Ratnayake, R.R., and Gnanavelrajah, N (2018). Assessment of Potential Removal of Nitrate from Synthetic Medium by Selected Herotrophic Bacteria – An Approach for Reducing Nitrate in Groundwater of Jaffna Peninsula. Proceedings of the 7th YSF Symposium of National Science and Technology Commission:167-169

  • Sivachanthirika, A and Gnanavelrajah, N (2018). Production of quality compost using locally available resources. Proceedings of the 7th YSF Symposium of National Science and Technology Commission:146-148

  • Aasir, A.M., Gnanavelrajah, N., Fuad Hossain, M.D., Wasantha Kumara, K.L and Ratnayake, R.R (2018).Effect of nutritional stress on cyanobacteria during its mass culture. Proceedings of the 7th YSF Symposium of National Science and Technology Commission:1-6

  • Vijayakumar,S., Ratnayake,R.R. and Gnanavelrajah, N (2016). Assessment of lead and cadmium levels in selected soils of Anuradapura of Sri Lanka. Proceedings of the international symposium on Agriculture & environment, Faculty of Agriculture, University of Ruhuna, Sri Lanka.pp 121-123

  • Vijayakumar.S,. Ratnayake.R.R and Gnanavelrajah.N (2015). Assessment of soil micronutrient availability in different cultivated and uncultivated soils in jaffna peninsula. Proceedings of the Young Scientists Forum (YSF) of National Science and Technology Commission (NASTEC), Sri Lanka, 23 January.


  • Senthuran, S and Gnanaelrajah, N. (2015). Effects of biochar produced from different feed stock materials on soil properties in sandy regosol of Jaffna, Sri lanka. Proceedings of the Young Scientists Forum (YSF) of National Science and Technology Commission (NASTEC), Sri Lanka, 23 January.


  • Thurairajah, A., Ratnayake, R.R., Gnanavelrajah, N and Kathirgamanathan, M (2015). Biodegradation of eichhornia crassipes towards biofuel production. Proceedings of the Young Scientists Forum (YSF) of National Science and Technology Commission (NASTEC), 23 January.


  • Vijayakumar.S,. Ratnayake.R.R and Gnanavelrajah.N (2015). Effect of Cultivation, Elevation and Soil Depth of Soil on Soil Carbon and its Fractions in Jaffna District" Proceedings of 22nd Annual sessions, Jaffna Science Association, Jaffna, Sri Lanka, pp.


  • Anne Starina, J.L and Gnanavelrajah, N (2015). Duel Use of Alternanthera sessilis as a phytoremediator and a Vegetable. Proceedings of 22nd Annual sessions, Jaffna Science Association, Jaffna, Sri Lanka, pp.32


  • Vijayakumar.S,. Ratnayake.R.R and Gnanavelrajah.N (2015). Assessment of lead and cadmium levels in selected soils of Jaffna District of Sri Lanka. Proceedings of the International Conference on Dryzone Agriculture 2015.


  • Thurairajah, A., Mohanan, K., Renuka,R.R and Gnanavelrajah.N (2015). Eichhornia crassipes as an Organic Manure. Proceedings of 22nd Annual sessions, Jaffna Science Association, Jaffna, Sri Lanka, pp.32


  • Rosanthan, T. Ratnayake, R and. Gnanavelrajah, N (2014). Soil Organic Carbon Fractions, Aggregate Stability, Nutrient Availability and their Interrelationships in Tropical Cropping Systems. 20th world congress of soil science, 2014.6, 49.


  • Sivarajah, S and Gnanavelrajah, N (2014). Potential to grow Alternanthera sessilis in Kitchen waste water hydroponic system. Proceedings of 21st Annual sessions, Jaffna Science Association, Jaffna, Sri Lanka, pp.32


  • Raguraj,S. Ratnayake, R.R. and .gnanavelrajah, N (2014). Carbon fractions and nutrient status of soils in Iranamadhu irrigation command area, Kilinochchi. Proceedings of the international conference on Agriculture and Forestry 10 – 11 June 2014.


  • Sivarajah, S and gnanavelrajah, N (2014). Potential to grow ipomoea aquatica in kitchen wastewater hydroponics. Proceedings of the international conference on Agriculture and Forestry 10 – 11 June 2014.


  • Gnanavelraja, N (2013).Sustainable Management of Agricultural Land-uses Towards Local and Global Benefits. Abstract Proceedings of the second Round table on Sustainable Consumption and Production. 21st – 22nd February, 2013, Colombo


  • Nilushiny, A.M,Jegajeevagan, K and Gnanavelrajah, N. (2013). Effect of Three Types of Charred Biomass on Important Soil Properties of Calcic Red Yellow Latosols(Abs.). Proceedings of 20th Annual sessions, Jaffna Science Association, pp.14.


  • Panneerchelvam, P.,Jegajeevagan, K and Gnanavelrajah, N. (2013). Effect of Three Types of Charred Biomass on Important Soil Properties of Vaddukoddai Series (Abs.). Proceedings of 20th Annual sessions, Jaffna Science Association, Jaffna, Sri Lanka, pp.12


  • Jegajeevagan, K and Gnanavelrajah, N. (2013). Assessment of Soil Organic Matter and Other Dynamic Properties from Selected Vegetable Cultivating Fields in Jaffna(Abs.). Proceedings of 20th Annual sessions, Jaffna Science Association, pp.08


  • Sivarajah, S and Gnanavelrajah, N (2014). Potential to grow Alternanthera sessilis in Kitchen waste water hydroponic system. Proceedings of 21st Annual sessions, Jaffna Science Association, Jaffna, Sri Lanka, pp.32


  • Ambihai, S and Gnanavelrajah, N (2012). Effect of charred biomass additions on fertility characteristics of soil. Proceedings of the second international symposium, South Eastern University of Sri Lanka


  • Sundaralingam, T and Gnanavelrajah, N (2012). Potential of Water Hyacinth (Eichhornia crassipes ) to remove nutrient loads in water and as a source of nutrients. Proceedings of Jaffna Science Association Volume 19:30


  • Ambihai, S and Gnanavelrajah, N (2012). Impact of charred firewood on soil properties of Regosols in Jaffna Peninsula. Proceedings of Jaffna Science Association Volume 19:21


  • Jegajeevagan, S. DeNeve, N. Gnanavelrajah, N. Ameloot and S. Sleutel (2011). Effect of biochar on soil N mineralization and biochemical properties of vegetable growing soils of Jaffna, Sri Lanka. Proceedings of the10th International Conference of the East and Southeast Asia Federation of Soil Science Societies October 10-13, 2011, Colombo, Sri Lanka


  • T. Kugendren, R.R. Ratnayake and N.Gnanavelrajah (2011). Assessment of soil carbon stocks in different land uses in Jaffna district, Sri Lanka, Proceedings of the 10th International Conference of the East and Southeast Asia Federation of Soil Science Societies October 10-13, 2011, Colombo, Sri Lanka. Pp:285 – 286.


  • N. Gnanavelrajah and T. Kandasamy (2011). Carbofuran leaching in selected soils and its accumulation in edible tissues. Proceedings of the 10th International Conference of the East and Southeast Asia Federation of Soil Science Societies October 10-13, 2011, Colombo, Sri Lanka. pp:47-48


  • Sundaralingam, T and Gnanavelrajah, N (2011).Phytoremediation for removal of nitrate and phosphorus in water.Symposium Proceedings of The water Professionals’ Day. October 1, 2011


  • Gnanavelrajah, N and T. Kandasamy (2011) Carbofuran leaching in selected soils and its accumulation in edible tissues. Proceedings of the10th International Conference of the East and Southeast Asia Federation of Soil Science Societies October 10-13, 2011, Colombo, Sri Lanka


  • Gnanavelrajah,N and R.P. Shrestha. (2011). Identification of the sustainable agricultural land-use options: A GIS based case study.Proceedings of the10th International Conference of the East and Southeast Asia Federation of Soil Science Societies October 10-13, 2011, Colombo, Sri Lanka


  • T. Kugendren, R.R. Ratnayake and N.Gnanavelrajah (2011). Assessment of soil carbon stocks in different land uses in Jaffna district, Sri Lanka,Proceedings of the 10th International Conference of the East and Southeast Asia Federation of Soil Science Societies October 10-13, 2011, Colombo, Sri Lanka

Postgraduate supervision


  • Supervisor for an MPhil student in the board of study Agriculture University of Jaffna titled “Screening of plant growth promoting rhizobacteriafrom onion rhizosphere and assessing their performance under field condition”. Completed in 2018


  • Supervisor for an MPhil student in the board of study Agriculture University of Jaffna titled “Isolation of Denitrifying Bacteria and their potential use in Nitrate removal from well water of Jaffna District”. Completed in 2019


  • Co-supervisor for an MPhil student in the board of study Soil Science, Post Graduate Institute of Agriculture, University of Peradeniya titled “Characterization of Soils in Northern Province”.


  • Supervisor for Master degree research in Environmental Management in the board of Study earth and environmental studies, University of Jaffna

  1. “Charred biomass as soil amendment”, Mr. Lawrence Christy Ananth

  2. “Nitrogen Removal from drinking water by edible semi- aquatic plants”, Mrs. J. L. Anne Starina

  3. “Charred biomass addition to reduce fertilizer requirement for beetroot”, Mrs. Asokaratnam Sirisanmugapiriya

  4. ”Nitrate analysis in vegetables” Ms S Yalini

  5. “Analyzing water quality and monitoring pollution level in irrigated ponds in Mannar district” Miss. Charles PancrasJeya Maria Nilani (Co-supervisor)