Journal of the Rubber Research Institute of Sri Lanka

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    Nodulation nitrogenase activity and major nutrient constituents of common cover crop legumes during early growth
    (Rubber Research Institute. Agalawatta, 1989) Jayasinghe, C.K.; Parker, C.A.; Kulasooriya, S.A.
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    Towards shorter immaturity and improved yields by mulching with rice straw
    (Rubber Research Institute. Agalawatta, 1992) Samarappuli, L.; Yogaratnam, N.; Samarappuli, P.; Mitrasena, U.
    In this study with immature Hevea brasiliensis, multing with paady straw around the base of the tree was found to be a better agronomic practice than growing leguminous cover crops such as Pueraria phaseoloides and Desmodium ovalifolium or allowing natural vegetation to grow in the inter-row area. Girthing had been much higher with mulching which resulted into reduction of the immature, unproductive period by approximately 18 and 12 month in comparison with naturals and creeping legumes respectively. In addition to early tapping, yield of latex was also higher during the early stages, increases in the region of 33perc. and 40perc. in comparison with creeping legumes and naturals respectively. The present value of the benefit achieved from mulching amount to Rs. 31,088/= per hectare of which Rs. 19,740/= is due to extra yield and the balance of Rs. 11,348/= is saving on inputs as a result of early maturity. Consequently, a net present value (NPV) of Rs. 7.8 million at national level can be achieved with the above practice at 50perc. level of adoption
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    Nutritional status of rubber growing soils in the Moneragala district
    (Rubber Research Institute . Agalawatta, 2005) Dharmakeerthi, R.S.; Silva, S.N.; Yakandawala, A.; Jayasinghe, W.K.
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    Distribution of Mn and Zn in rubber growing soils and its status in relation to selected management practices
    (Rubber Research Institute. Agalawatta, 2000) Samarappuli, L.; Perera, A.M.A.; Lalantha, H.K.; Rajapakse, W.
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    Management of covers under Hevea in Sri Lanka
    (Rubber Research Institute. Agalawatta, 1977) Yogaratnam, N.; Sulaiman, H.; Karunaratne, A.D.M.; Peiris, K.S.A.C.
    Results of two experiments, comparing the effects of leguminous creepers and naturals as ground covers on growth of immature rubber, are discussed. In one experiment the growthof rubber in plots under pure legume covers was better than that under naturals. Applications of extra nitrogen to trees in plots with natural covers improved their growth but the latter was not comparable to that in legume plots. In the pther experiments the increase in growth of rubber with higher levels of fertiliser nitrogen was observed irrespective of the type of cover. Application of phosphate to covers led to better tree girths than where the phosphate was applied on the trees, irrespective of the type of cover grown. These results are discussed in relation to the nitrogen content of rubber eaves, green matter, litter and C/N ratio of the litter of cover.