Growth response of Tobacco (Nicotiana tobaccum) for the enriched organic fertilizer

N. Kannan, M. Prabhaharan and V. Jayapiratha

The problem of municipal solid waste management is an alarming dimension in Sri Lanka during the last few decades. Due to the population growth and economic development, municipal solid waste per capita is increased daily. In Jaffna the collection and removal of municipal solid waste has become a serious problem. Toddy distillery Spent Wash (TDSW) is an effluent generated from the distilleries located in the Jaffna peninsula having good nutritional properties for the plant growth. But open dumping of this effluent causes severe environmental degradation. Hence the new concept was developed to convert the decomposable solid waste into organic fertilizer by spraying toddy distillery spent wash (TDSW) pit method of composting was selected for the experiment which was conducted in completely randomized design (CRD) with five treatments and three replicates. Treatments were T1,T2,T3,T4 and C those are once/week, once/two week, once/3week, and once/month and without spraying TDSW respectively. Statistical analysis showed that the total and available nitrogen in the compost produced from T1 had significantly differed from other treatments. Hence this T1 sample and sample from C were applied to the tobacco plants at the field. The average length and width of demarked leaves were measured at weekly interval. The maximum average length and width of the plants under the treatments T1 and C were 60cm, 52cm and 32cm, 27cm respectively. The average length for the T1 treated plants and C treated plants ranges from 32 -60 cm and 24 -52 cm respectively whereas width of the leaves for T1 treated and C treated plants ranges 14 -32 cm and 10 -27 cm respectively. There were significant differences in both length and width of the leaves from T1 to C. This was due to the good supply of nutrients from the DSW treated compost than the compost from the control. Based on the results the enriched compost is good for the plant growth and this would be the best option to manage both TDSW and Municipal solid waste without environmental degradation.

Key words: Municipal solid waste, Organic fertilizer, Tobacco, Growth

N. Kannan, M. Prabhaharan and V.Jayapiratha                                                                                                               Department of Agricultural Engineering, Faculty of Agriculture, University of Jaffna, Sri Lanka.

Aboveground tree carbon stocks of Lowland evergreen mixed vegetation at Gannoruwa

P.S. Pathinayake, M.D.P. Kumarathunga, S.P. Nissanka

Conservation of global forests is being considered as one of the sustainable ways of mitigating global warming, because forests are widely perceived to act as major sinks for atmospheric carbon. Estimation of carbon stocks of tropical forests are important for management, planning and for REDD initiatives.Therefore, this study was initiated to estimate existing carbon stocks of a Lowland evergreen mixed forest at Gannoruwa and how it has changed overtime.

The sampling points were selected using an unsupervised classified Landsat TM satellite image and topograhpic maps, considering the elevation level and the vegetation type. A GPS (Global Position System) was used to detect the correct location of sampling points and sampling plot size was set as 30m×30m. The dbh and height of each individual in the sampling plot which is greater than 5cm dbh was measured.

The dbh and height values were applied to a pre-derived regression equation and the above ground biomass was calculated. The equation was Y=exp {-3.3012+0.9439 ln(D2H)},(r2=0.9) where, Y is aboveground biomass, D is dbh and H is height. Assuming the carbon stock as 50% of the biomass, the above ground carbon stock was calculated. It was 146.4 mt/ha of carbon and the total aboveground tree carbon stock was 39.1×103 tons. The estimated basal area of the forest has declined compared to 25
year old recorded data and it reflects the carbon reduction of the forest due to anthropogenic activities.

P.S. Pathinayake, M.D.P. Kumarathunga, S.P. Nissanka
Department of Crop Science, Faculty of Agriculture,University of Peradeniya, Sri Lanka

Deterioration of soil quality with continuous plantation of teak (Tectona grandis)

N.T. Diyalawaththa, R.M.D. Alawathugoda and P.I. Yapa

A study was carried out at Rathmale teak Plantation, Thalawa to investigate the cause for the poor growth of teak saplings in a selected area. The study hypothesized that the poor growth and development of second rotation teak is a result of poor physical and chemical properties of the soil that gradually developed after the conversion of natural forest to plantation. Three sites, poorly grown teak plants, normally grown teak plants, natural forest land were selected. Soil samples from top and sub layer were analysed for pH, Electrical conductivity (EC), Nitrogen, Phosphorus, Potassium, CEC, Soil organic matter (SOM), Texture and Bulk density (BD). Bulk density, SOM and EC were Session I – Forest and Natural Resource Management Significantly different between site one and site two. Higher BD, lower SOM and EC are key components of the soil quality and the changes may have led to the poor growth of Teak in site one. It was therefore clearly evident that the change in soil quality as a result of the conversion of natural forest to teak plantation is linked with the poor growth of teak saplings in the area under investigation.

N.T. Diyalawaththa1, R.M.D. Alawathugoda2 and P.I. Yapa1
1Department of Export Agriculture, Sabaragamuwa University of Sri Lanka
2Forest Research Center, Forest Department, Sri Lanka