Abstract
Tea culture experiments were conducted using different fertilizer and irrigation regimes in a mature tea field on flat land and a newly-planted tea field on sloping land in Kagawa Prefecture, Japan. The three regimes tested in the mature tea field were: (i) solar pomp controlled-low-rate drip irrigation with liquid fertilizer in nitrogen-rich groundwater (LI) (ii) conventional fertilizer rate (C), (iii) conventional-flow-rate irrigation with conventional fertilizer rate (CI). The dry weight of tea leaves harvested in the LI plot was 19-25% more than in the C plot and slightly more than in the CI plot in the first 2 years after the change of management. The quality of tea leaves was almost the same in the LI plot as in the C and CI plots. The applied N in the LI plot was 51-58% of the amounts applied in the CI and C plots with 568 kg-N ha^<-1> fertilized. In the LI plots, 120 kg ha^<-1> of applied N was derived from extracted groundwater applied as irrigation. In the LI plot, improvements of soil chemical properties such as increase in soil pH, decreases in EC, NO_3-N, available P, and exchangeable K were observed in the organic, surface and subsurface layers in the inter-row space. The LI and CI regimes were also applied to newly-planted tea trees on a sloping field. The irrigation enabled the trees to establish successfully. The growth of tea trees in the LI plot was not significantly different from that in the CI plot at 18 months after transplanting. The amount of N applied in fertilizer in the LI plot was less than half that in CI plot.
