Effects of Foliar Fertilizer Application on Quality of Tea (Camellia sinensis) Grown in the Kenyan Highlands

Abstract

In Kenya, foliar fertilizers have not found use in tea production despite their numerous advantages as exhibited in other crops. A fertilizer trial test was established in three sites of the major tea growing regions, with 36 plots per site to determine the effects of foliar fertilizer application on tea quality. Two foliar fertilizers were tested; foliar fertilizer 1 (FF1) and foliar fertilizer 2 (FF2), with a positive control of soil fertilizer (SF) and a blank. Two leaves and a bud tea samples were collected every two weeks after each foliar fertilizer application. These were then analyzed for tea quality (total polyphenols, TP), nutrient residues for the different clones and geographical locations. The TP contents for clone TRFK 31/8 were as follows: FF1 = 17.8%, FF2 = 17.9%, SF = 16.56% and Zero = 17.4%. Tukey-Kramer pair wise comparison test results between the foliar fertilizers and SF showed that the FF1 (HSD = 4.78) and FF2 (HSD = 5.27) fertilizers had significantly (P < 0.05) higher levels of TP content as compared to control SF fertilizer. Nutrients analyzed had average means as follows: N = 4% - 5%, P = 0.25% - 0.28%, K = 1.35% - 1.69%, Ca = 0.3 - 0.5 ppm, Mg = 0.19 - 0.27 ppm, Mn = 0.05 - 0.13 ppm, Zn = 25 - 40.5 ppm, Cu = 11 - 17 ppm and Fe = 72 - 122 ppm. The nutrient residue levels had non-significantly statistical differences at P < 0.05 level between pairs of zero applied plots and the FF1, FF2 and SF applied plots respectively. It was concluded that the foliar fertilizers increased the TP content in tested tea samples and the nutrients analyzed were all within the dietary reference intake (DRI) levels for SF, FF1 and FF2. Overall, the foliar fertilizer increased the quality of the tested tea samples.