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Effect of Different Weed Management Strategies on Population Changing Pattern of Pennisetum polystachion in Coconut Plantations of Sri Lanka Senarathne, S. H. S.; Udumann, Shashi Shermila
International Coconut Community Journal Vol 35 No 1 (2019): CORD
Publisher : International Coconut Community

Pennisetum polystachion is a major problematic monocotyledonous weed species and a perennial problem in intermediate zone of coconut plantations in Sri Lanka. This study was carried out to evaluate the impacts of different management systems on P. polystachion seedling emergence patterns. The tested treatments were application of glyphosate (T1), cover cropping with Pueraria phaseoloides (T2), tractor harrowing (T3), tractor slashing (T4) and tractor ploughing (T5). All the treatments were applied twice a year except T2. As T2 cover crop at the initiation of the experiment and over grown conditions were managed by harrowing once a year. Based on the reduction in weed biomass, cover cropping (T2) was the best to reduce the P. polystachion population and to reduce P. polystachion seedling emergence density in the field. Chemical weeding was the second-best method to control the P. polystachion population in the field. The effectiveness of slashing in reducing weed seedling emergence density was lower than cover cropping and chemical weeding methods. The weed seedling emergence densities were almost similar in ploughed and harrowed plots. The seed depth of emerged seedling was very high in harrowed and ploughed treatments when compared to other treatments. Results given by T3 and T5 indicates that loosening the soil creates more favorable environment for the germination of weed seeds buried in soil. Therefore, it can be argued that the elimination of weed seeds in the top 2 cm or 4 cm in the soil seed bank by any means is likely to reduce the level of weed infestation by about 60% to 95%. Results also indicated that burying rhizomes in ploughing and harrowing treatment plots at the depths below 30 - 40 cm is effective in controlling germination of this weed species. This experiment also suggested that keeping rhizomes on the soil surface without burying for durations of 5 – 15 days would produce weak plants with poor development.

The Influence of Vermicomposting Technology on Solubility of Eppawala Rock Phosphate Senarathne, S. H. S.; Udumann, S. S.
International Coconut Community Journal Vol 34 No 2 (2018): CORD
Publisher : International Coconut Community

The application of Eppawala Rock Phosphate (ERP) could be an economic alternative to the use of imported phosphorus fertilizer for certain annual as well as perennial crops like coconut in acid soils. But, its low solubility limits direct application. For Vermicomposting technology, which is a biodegradation process of plant and animal waste materials through earthworms, has been tested for increasing the solubility of ERP. Fresh Gliricidia leaves, fresh cow dung and grasses were mixed 1:2:1 ratio as the basic composting mixture and ERP was mixed at the ratio of 10% and 20% to the composting materials. Forty numbers of earthworms were added to each of the plastic containers with the composting mixture, having five replicates per treatment. Addition of ERP in to mixture showed no effect on the multiplication rate of earth worms. The nutrient availability of compost was measured with time and compared with the control (T1). Each treatment had the similar amount of nitrogen in the system and that indicates the addition of rock phosphate has a minimal effect or no effect on conversion or losses of available nitrogen. Addition of ERP increased the availability of phosphorus and it was significantly higher in T4 and T3 than other treatments. Available phosphorus value was significantly increased from 4% (T5 and T6) to 9 % in T3 and T4 treatments. Total potassium content decreased in all treatments compare with control. Therefore, vermicomposting can be utilized to increase the solubility of ERP while increasing the available phosphorus in the end product.

Effect of Vermicompost on Growth of Coconut Seedlings under Field Conditions in Sri Lanka Senarathne, S. H. S.
International Coconut Community Journal Vol 34 No 1 (2018): CORD
Publisher : International Coconut Community

Organic matter contributes in maintaining soil fertility in agriculture. Vermicompost is rich in plant nutrients and recognized as potential organic manure source for many crops. In this experiment, different amount of vermicompost and inorganic fertilizers were tested. The objective of the research was to evaluate the effect of vermicompost on the growth of coconut seedling in the field conditions and to reduce the cost of production of coconut plantations. Treatments were arranged in a Randomized Complete Block Design (RCBD) with three replicates. The experiment consisted of three different fertilizer treatments with vermicompost (100%) + Dolomite 500g (T1), Inorganic fertilizer (Young Palm Mixture) + Dolomite (T2) and vermicompost + Inorganic fertilizer (Young Palm Mixture) + Dolomite (T3). Growth measurements revealed A significantly higher seedling girth, leaf production rate and early highest coconut seedling flowering percentage in the vermicompost base integrated fertilizer applied treatment when compare with other two treatments. This experiment had brought out that application of vermicompost base integrated fertilizer application system is beneficial for coconut seedlings in the field for the better field establishment and vigorous seedling growth.

Influence of Long Term Application of Green Manure on the Productivity of Coconut Cultivated in Reddish Brown Latosolic Soils in Sri Lanka Senarathne, S. H. S.
International Coconut Community Journal Vol 33 No 2 (2017): CORD
Publisher : International Coconut Community

Organic matter contributes in maintaining soil fertility in agriculture. Green leaf biomasses of Gliricidia sepium and Tithonia diversifolia are high in plant nutrients and recognized as potential green manure sources for many crops. In a field experiment carried out in a coconut plantation with Reddish Brown Latosolic soil, two green manure crops were grown to study their abilities and establishment in coconut avenues and to evaluate their effect on nut yield. In situ green manuring, especially with legumes, had the most beneficial effect on soil improvement. The use of green biomass alone has improved soil properties. The biomasses of Gliricidia and Tithonia decomposed rapidly after application to the soil, and incorporated biomass would be an effective source of N, P and K for crops. Results showed that, coconut yields were significantly increased with the incorporation of green biomass of Gliricidia and Tithonia than with commercial inorganic fertilizer application. Mean nut yield for five years in the green manure applied plots was (37-46%) significantly (P < 0.05) higher, compared to that of the inorganic fertilizer applied plots towards the latter part of the experiment. Addition of green manure has significantly (P < 0.05) improved the soil parameters i.e. soil N (by 75%), organic C content (by 86%) and soil microbial activity (by 52%). Soil bulk density has been reduced by 20% which enhances the root growth. The improvement of soil moisture content by 92% is of great importance for coconut in withstanding the frequent dry spells which are on increasing trend with the present climatic change situations. There was no significant effect of green manures on soil pH and P but P content was improved with the use of green biomasses of Gliricidia and Tithonia.

Feasibility of using Problematic Aquatic Weeds in Productive Manner by Generating Vermicompost in Coconut Triangle Area of Sri Lanka Senarathne, S. H. S.; Dayananda, H. N.; Atapattu, A. A. A. J.; Raveendra, S. A. S. T.
International Coconut Community Journal Vol 33 No 1 (2017): CORD
Publisher : International Coconut Community

Aquatic weeds cause severe productivity loss in agriculture. These plants invade lakes, ponds, rivers, canals and agricultural fields, becoming noxious weeds. The study was conducted at the vermicomposting unit of the Coconut Research Institute, Lunuwila, in the Low country Dry Zone of North Western province of Sri Lanka from August 2012 to May 2013 to find out the feasibility of producing vermicompost from three aquatic weeds; Salvinia molesta, Eichhornia crassipes and Lagenandra toxicaria. Vermicompost and compost were prepared separately from aquatic weeds and Gliricidia and Guinea grass combinations. During the vermicomposting process, growth parameters of earthworms; number of earthworms, was taken in every ten days interval further, physical, chemical and biological properties of compost and vermicompost were analyzed. Experiment was carried out in a Complete Randomized Design (CRD) with eight treatment and five replicates in each treatment. Eichhornia and Salvinia recorded the highest adult earthworm number and juvenile number with the lowest mortality rate. Electrical conductivity (6.75 dSm-1), organic carbon (13.21%), phosphorous (3.61%), potassium (5.03%) and calcium (6.12%) were significantly high in Lagenandra toxicaria, Gliricidia and Guinea grass treatment was significantly high in nitrogen content (3.93%) and low in C: N ratio (2.51), compared to aquatic weeds. Salvinia showed comparatively higher nitrogen content and lower C: N ratio among aquatic weeds. Both Eichhornia and Lagenandra showed significantly higher microbial activity. Vermicompost was superior in all the properties compared to compost in the same substrate. The study revealed that aquatic weeds such as Salvinia molesta, Eichhornia crassipes and Lagenandra toxicaria which are readily available in the coconut triangle can be successfully used to produce Vermicompost. It can be concluded that the Vermicompost produced from aquatic weeds locally could be a suitable organic fertilizer for organic coconut farming in Sri Lanka.

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