Agriculture Reference
In-Depth Information
Lowland rice
0 mg N kg
-1
300 mg N kg
-1
BRA 02654
FIGURE 3.18
(
See color insert.
) Growth of lowland rice genotype BRA 02654 at low and high N levels.
Half of the N was applied at sowing and the remaining half at the active tillering growth stage.
use. If the value of a soil test can be treated or expressed as an independent variable, fewer personal
judgments are required and more accurate fertilizer recommendations will be made (Melsted and
Peck, 1973). Melsted and Peck (1973) reported that a sound soil testing program is best and perhaps
the only way to determining what constitutes adequate but not excessive fertilizer use for high and
efficient crop production.
A soil test is defined as a physical, chemical, or biological procedure that estimates the suit-
ability of the soil to support plant growth (Soil Science Society of America, 2008). Soil test
calibration is defined as the process of determining the crop nutrient requirement at different soil
Lowland rice
0 mg N kg
-1
300 mg N kg
-1
BRA 051077
FIGURE 3.19
(
See color insert.
) Growth of lowland rice cultivar BRA 051077 at low and high N levels. Half
of the N was applied at sowing and the remaining half at the active tillering growth stage.
