NPK (S) fertilizer use in commercially cultivated clone BBK 35 in different tea growing regions of Kenya: I. Experimental design and initial soil chemical properties.

Abstract

An experiment was set up in five sites by superimposing on commercially grown plantations consisting of one popular tea cultivar, clone BBK 35 at Timbilil estate, Kericho; Changoi Estate, lower Kericho; Magura-Kipkebe estate, Sotik; Sotik highlands estate, Sotik; and Karirana estate, Limuru. The experiments in all the sites were laid out in a randomised complete block design consisting of five nitrogen rates and three plucking frequencies replicated thrice and aimed at establishing if fertilizer requirements and plucking rounds of tea varies with soil properties and locality. This paper summarizes the initial soil chemical characteristics of the five sites sampled at 0-20 cm and 20-40 cm soils depths. The tea soils were all strongly acidic with mean pH values of 3.84 at Karirana, 3.89 at Timbilil, 3.99 at Changoi, 4.31 at Magura, and 4.81 at Sotik Highlands. The extractable base nutrient elements however differed significantly from site to site with extractable potassium, calcium and magnesium having the ranges 250-482 ppm, 182-1808 ppm, and 9.4-179 ppm, respectively. The base nutrients also differed along the soil profiles. Soil extractable phosphorus content varied from 12.7 ppm at Sotik Highlands to 23.1 ppm at Changoi, while soil extractable manganese levels ranged from a mean of 63 ppm at Karirana to 149 ppm at Timbilil. The changes in the soil properties arising from the nitrogen and plucking frequencies are reported in a follow-up paper under the same series.