Effect of using sub soil with organic materials as a substitute to top soil in potting medium of rubber nurseries

The study examined the influence of sub soil with organic material or materials compared to top soil on the growth of Hevea seedlings. Substitution of top soil with sub soil and five locally available organic materials on growth and nutrient contents of the rubber plants (Hevea brasiliensis) during nursery stage were studied. Only top soil was used as control treatment (T1). The experiment was included nine treatments and the combinations of the treatments were arranged in a completely randomized block design with twenty replicate plants. Plant growth parameters viz; diameter, height, leaf area and plant dry matter accumulation were measured periodically at the end of before and after budgrafting stages. Macro nutrient concentrations in leaves of the after budgrafting plants were determined to assess the nutritional status of the plant. Improved growth assessments; plant height, leaf area, plant dry matter accumulation and enhanced leaf nutrient contents could be observed with the treatment having sub soil and organic materials such as coir dust, poultry and refuse tea. Almost all growth assessments (94%) and all leaf nutrient contents (100%) related to sub soil with organic materials; coir dust or poultry or refuse tea or coir dust and poultry treatments gave significantly higher or no significant effect compared to top soil (T1). Deterioration of growth assessments; plant height, leaf area and plant dry matter accumulation could be observed with the treatments having sub soil and organic materials such as paddy husk and saw dust. All growth assessments (100%) related to sub soil with organic materials; paddy husk or saw dust or poultry and paddy husk or poultry and saw dust treatments gave significantly lower or no significant effect compared to top soil (T1). In general, many occasions (93%) leaf nutrient contents in sub soil + organic material or materials gave significantly higher or no significant effect compared to top soil (T1). It is evident from results that significantly higher many growth parameters associated with sub soil with coir dust could be accepted as a superior medium for polybag plants compared to the RRI recommended top soil only potting medium. Moreover, sub soil with refuse tea or poultry could be used as a substitute for top soil only medium without any failure.