V. Subramanian , C. Buvaneswaran , K. Rajagopal , M. George

Abstract

Biomass production and nutrient cycling studies were carried out in a young teak (Tectona grandis L. f.) plantation of five year old (density 2,500 trees ha^-1). The trees attained an average girth and height of 23.1cm and 7.6m, respectively and the above ground biomass (agb) amounted to 76.9 t/ha, of which stem wood contributed 60%. The percentage of ischolar_main to agb was 20.5%. Investigations on nutrient content in the standing crop have shown that the per cent concentration of nitrogen (N), phosphorous (P), potassium (K), calcium (Ca) and magnesium (Mg) were highest in leaf. But on unit area basis, wood accumulated the major portion (39 to 60%) of all nutrients. Among the nutrients, maximum accumulation was accounted for Ca (1,619 kg ha^-1) and the minimum for P (178 kg ha^-1). With reference to nutrient return via litter, it was observed that the total litter produced was 4,574 kg ha^-1 and the nutrients returned amounted to 46 kg ha^-1 N; 3 kg ha^-1 P; 39 kg ha^-1 K; 86 kg ha^-1 Ca and 21 kg ha^-1 Mg. Studies on interception of rainfall and nutrient return through rain-wash have shown that among the nutrients return was highest for Ca (1.87 kg ha^-1) followed by Mg (1.09 kg ha^-1), K (0.98 kg ha^-1), N (0.36 kg ha^-1) and the least for P (0.11 kg ha^-1). Nutrient cycling on an annual basis was worked out for the plantation and it was found that of the total uptake of various nutrients (178kg N ha1 yr1, 248 kg K ha^-1 yr^-1, 387 kg Ca ha^-1 yr^-1 and 109 kg Mg ha^-1 yr^-1, 74 to 91% was retained in the non-photosynthetic biomass and the rest returned to soil. These results were compared with nutrient cycling in 20-year-old teak plantation and found that at younger age teak retains more nutrients in its biomass. As the plantation gets older, it retains less and returns more quantity of nutrients. These results suggest that as the age of plantation increases, teak becomes an eco-friendly species by not adversely affecting the ecology of the site.

Keywords

Nutrient Cycling, Young Teak Plantation, Coimbatore, Tamil Nadu

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K. Rajagopal , C. Buvaneswaran , V. Subramanian , M. George

Abstract

Studies on different pathways of nutrient return through litterfall and rain-wash were carried out in a young teak (Tectona grandis L. f.) plantation at five years age (Density 2500 trees/ha). The total litter produced was 4574 kg/ha and the nutrients returned amounted to : nitrogen - 46kg/ha; phosphorus- 3 kg/ha; potassium 39kg/ha; calcium 86kg/ha; and magnesium 21kg/ha. Studies on interception of rainfall have shown that, the total incident rainfall recorded for this study during the year 2000 was 1013 mm. Of which, 28.97% was intercepted by the canopy, while 7.66% was accounted for stemflow and 63.37% for through fall. With regards to nutrients return through rain-wash, it was found that, throughfall returned more quantities of all nutrients, than stemflow. Of the total return (litter + rain wash) of various nutrients, maximum amount (kg/ha) of return was accounted for calcium (87.40) followed by nitrogen (46.56), potassium (40.31), magnesium (22.13), and the least for phosphorus (3.31). Among these two pathways of nutrients return, litterfall contributed greater amount of all nutrients (from 95 to 99%), when compared to rain wash (0.8 to 4.9%). These results were compared and discussed with nutrients return and nutrient cycling in 20 years old teak plantation and suggest intensive silvicuItural practices in teak plantations during the initial stages of growth to enhance the productivity.

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