DISCUSSION
The three common fertilizer practices
had no significant effect on the soil nutrient status.
There were few significant differences in the
nutrient status found among districts and between
fertilizer practices except with respect to N, OC
and CEC for districts, and soil pH, available K
and exchangeable Mg for fertilizer practices which
were significant. Highly significant differences
between the nutrient levels in the surface soil and
subsoil were also observed (Table 2) with the
exception of pH that was found to have similar
values at the two depths.
The fact that the pH level in the soils was
the same and at an optimum level at both soil
depths sampled could be explained by the low
impact of the land use practices carried out in
Bhutanese apple orchards; the soils are still rich
and have not been overexploited by the current
farming practices. The lower nutrient levels in the
subsoil layer compared with those of the surface
layer could have been due to the abundance of
active apple feeder roots in the 21–40 cm soil layer
or the roots of orchard grasses at same layer might
have taken up the available nutrient.
The organic fertilizer has had a positive
effect on soil as indicated by its corresponding
higher pH level. The continuous application of
chemical fertilizer in apple orchards decreases the
soil pH due to nitrification of the ammonium
fertilizers or urea which results in increasing