Abstract

Pot culture experiments were conducted on two bench mark soil series of Kerala (varying in available P status) at the Radiotracer Laboratory, Kerala Agricultural University, with the objectives of studying the effect of organic and inorganic sources of P on the growth of teak seedlings, uptake of P, percent P derived from fertilizer (% Pdff), P use efficiency (PUE) and A value using ³²P. The treatments consisted of combination of four levels of weed compost (0, 100, 150 and 200 g pot^-1) as organic source and three levels of inorganic P (4, 8 and 16 mg P kg^-1) in the form of KH₂PO₄. The experiment was laid out by adopting a factorial completely randomized block design. Results revealed that in both soils with varying levels of P, application of inorganic P at the rate of 4 mg kg^-1 increased % Pdff and P use efficiency compared to higher levels of P application. Combined application of different levels of compost with inorganic P at the rate of 4 mg kg^-1 resulted in significant improvement in % Pdff and P use efficiency. But shoot biomass, total P uptake and A value increased with increasing levels of inorganic P. Combined application of different levels of compost with inorganic P at 16 mg kg^-1 also significantly improved shoot biomass, total P uptake and A value. The results in general indicated that combined application of compost with inorganic P fertilizer was more effective than application of inorganic fertilizer alone in both soils for enhanced absorption and use efficiency of P. Thus the integrated use of fertilizer and manure will enhance the productivity of teak plantation.

Key words: Phosphorus, ³²P, % Pdff, P use efficiency, teak.