Leaf litter addition and nutrient recycling in two clones of rubber (Hevea brasiliensis Muell. Arg.) at Vellanikkara estate of Kerala Agricultural University

Abstract

The present study deals with the quantification of leaf litter addition and nutrient recycling in two clones of rubber in the Vellanikkara Estate of kerala Agricultural University , Trichur . Two different methods of collection were adopted for litter collection in both the clones RRII 105 and RRII 118. Wintering was found to start on 23rd November, 1993 for clone RRII 105 and continued till 12th February , 1994 whereas in RRII 118 wintering strated by 25th November, 1993 and continued till 17th February , 1994. Peak leaf fall was noticed in the month of January for RRII 105 whereas it was in the month of February in the case of RRII 118. Thus clonal variation do exist for the wintering pattern. The total leaf litter production was estimated to the 4954.297 kg for RRII105 and 4584.558 kg for RRII 118. The nutrients contributed through leaf litter during wintering in the clone RRII 105 were 72 kg N, 2 kg p, 57 kg K, 59 kg ca and 12kg mg whereas for the clone RRII 118 it was 61kg N, 2kg p, 43kg k , 79 kg ca and 9kg mg . The clone RRII 105 contributed more litter as well as nutrients than the clone RRII 118. Contrary to the previous years the nutrient levels in the leaf litter did not follow a regular pattern during the wintering period . The presence of green leaves shed due to high wind velocity resulted in an increased level of nutrients in some collection s. It was also observed that the contribution of N, K and Ca were more during the wintering period whereas p was more prior to peak wintering and Mg was more after peak wintering. Comparison of nutrient status in soil samples collected from the area enclosed by net and outside sites showed that removal of leaf litter resulted in relatively lower levels of soil nutrients in the top soil . The leaf area worked out during the study was 6.44 for the clone RRII 105 and 5.53 for clone RRII118. The study also revealed that enclosing the trees with net is the best method to quantify the leaf litter addition . The expensive and cumbersome procedure of providing nets cannot be replaced by collecting the leaf litter from a marked area provided with 15 cm high fencing . The leaf litter accumulated in the fenced area was always less and varied from 27 to 71 per cent of the quantity of litter collected by providing net to cover the canopy all around the trees.