Wj. Fielding et Dp. Sherchan, The variability of level and sloping terraces in eastern Nepal and the implications for the design of experiments, EXP AGRICUL, 35(4), 1999, pp. 449-459
Nepalese hillside terraces are classified into two broad groups, sloping or
bari terraces which are only rainfed, and level or khet terraces which are
commonly flood irrigated but may also be rainfed. Although such terraces m
ay be adjacent, the process of irrigation by flooding and puddling changes
the pattern of variability both within and between terraces. Data collected
from Pakhribas Agricultural Centre, Dhankuta, Nepal, were used to describe
this variability. The variability is manifest not only in the soil charact
eristics of the two terrace types, with khet terraces being more uniform th
an bari terraces both within and between terraces, but also in the variabil
ity of field experiments on the two terrace types. However, both terrace ty
pes exhibit similar patterns of variability which influence the design of e
xperiments. These include the following: a gradient between the terrace ris
er and wall which is generally more important than gradients along the terr
ace, variability within terraces which can preclude the assumption that plo
ts on the same terrace are similar, and variability between terraces which
requires experimental units in the same block to be assigned to the same te
rrace.