Abstract:
Soil samples were collected at a depth of 0-15 cm and 15-30 cm from experimental plots
of a long term field trial carried out at the Tea Research Institute of Sri Lanka,
Talawakelle to investigate the performance of ammonium sulfate (SA) and urea at two
rates (240 and 360 kg N ha' 1 yr'1) in five combinations of SA and urea (urea : SA =
100:0, 75:25, 50:50, 25:75 and 0:100). The samples were analyzed for soil pH, Borax
extractable phosphorus, DTP A extractable Mn, Cu, Fe and Zn.
The results indicate that the soil pH (water and 0.01 M CaCfe) decreased linearly with the
proportional increase of ammonium sulfate in the SA/Urea combination at both (0-15 and
15-30 cm) depths. There is a decreasing trend of soil phosphorus with the decrease in soil
pH at both depths at both N levels. However these changes are not statistically
significant.
DTP A extractable Iron availability was linearly increased as soil pH (water and 0.01 M
CaCb) decreased at both (0-15 and 15-30 cm) depths at both N levels (240 and 360 kg
N). Further zinc, copper and manganese concentration also linearly increased (not
statistically significant) as soil pH (water, 0.01 M CaCfe) decreased, at (0-15 and 15-30
cm) depths at both levels of N (240 N and 360 N).
