Abstract

Simon Calvin, Nduta Hanjari and Bedan H. Jacques

As the most important cultural practices for tea production, single effects of nitrogen (N) and potassium (K) fertilization on yield are well documented but their interactions and impact on their use efficiencies are poorly understood. It was necessary therefore to assess interactions and impact on their use efficiencies in tea cultivation as influenced by fertilizer application rates. This objective led to a comprehensive field investigation in strongly acidic soil tea plots at Tea Research Foundation of Kenya, Kangaita substation in Kerugoya using clone TRFK 11-4 in a 3x3, NxK RCB design. Treatments were nitrogen (0, 100 and 200 Kg N ha-1 ) as urea and potassium (0, 40 and 80 Kg K 2O ha-1 ) as muriate of potash (MoP) replicated thrice. A uniform single dose of phosphorus (40 Kg P2O5 ha-1 ) was applied. Tea yield, plant biomass and plant nutrient concentrations were measured for calculation of plant nutrient uptake and efficiencies. Increased nitrogen rates from 100 to 200 Kg N ha-1 increased agronomic efficiency of nitrogen from 0.33, 0.93 and 0.33 to 1.32, 1.08 and 0.37 at respective rates of potassium. Increased nitrogen rates from 0 to 200 Kg N ha-1 increased agronomic efficiency of potassium from - 0.59 and 0.04 to 6.67 and 1.26 at respective rates of potassium.