Nitrogen (N) fertilizer management for sugarbeet (Beta vulgaris L.)
production requires more precise information than for most crops.
Inadequate N limits plant growth and root yield, but excess N may
reduce both sucrose percentage and recoverable sucrose (7). Also,
excess N may stimulate more leaf growth than necessary. The rate and
timing of N fertilizer applications are not only important in supplying
crop N needs, but can influence the amount of N lost by leaching and
denitrification. Soil and plant tissue tests can provide essential data For
decision-making for efficient and economical use of N fertilizer.
Recent studies have shown that the NO?-N level in the soil before
planting is closely related to sucrose production when N is limiting (8,
12). Inclusion of the N mineralization capacity of the soils would be
expected to improve the relationship. Stanford and Smith (14) showed
that the mineralization capacity varies with soil type and location.
Therefore, a soil test for N that would have general applicability should
include the mineralization capacity of the soil, and the interpretation of
these tests should include some knowledge of expected irrigation practices.
A soil test for NO?-N may suffice as an index of N fertilizer needs
for a given soil and irrigation level.
Recently, Carter et al. (5) showed that sucrose production was
closely related to available soil N, as indicated by a soil test that included
both mineralizable N and NO?-N. The objective of our study was to
evaluate the soil test-yield relationship, developed from experimental
data at one location in south central Idaho, for predicting N fertilizer
needs throughout southern Idaho under various irrigation management
practices
