Humid Tropical Tea Response to Phosphorus—The Prognostic Concentration in Leaf and Soil

Abstract

Phosphorus (P) fertility information is needed for tea to optimize tea production in southeast Asian countries. Two-year field experiments were conducted in four tea gardens of the Terai and the Dooars regions of India to determine the response of tea leaf yield and leaf P concentration to P application rate from 0 to 44 kg ha −1 in 11 kg increments, and to determine the relationship of leaf yield on leaf P concentration and soil extractable P (Bray-1P) at different intervals of the tea yield period. Tea leaf yield response to P fertilizer applications varied (r 2 = 0.775 * ) among gardens. Leaf tissue P at 45 days after fertilization (DAF) was related to relative leaf yield (r 2 = 0.783 * ). P concentration of 3.62 g kg −1 dry matter (dm) was critical according to both the quadratic response plateau (QRP) model and the 'old' Cate-Nelson (CN) procedure. Soil extractable P at 90 DAF had a low correlation (r 2 = 0.392 * ) with relative leaf yield, and P concentrations of 24.9 kg and 20.1 kg P ha −1 were critical for optimum yield as determined by the QRP and CN models. On the basis of critical values of leaf P, P amendments could possibly be applied at 45 DAF to enhance tea yield.