Agriculture Reference
In-Depth Information
Lowland rice
0 mg N kg
-1
300 mg N kg
-1
BRA 051077
FIGURE 3.20
Root growth of lowland rice genotype 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.
test values (Soil Science Society of America, 2008). The basic terminologies related to soil test
calibration are soil test correlation, soil test critical concentration, and soil test interpretation.
According to the Soil Science Society of America (2008), these terms are defined as follows: Soil
test correlation is defined as the process of determining the relationship between plant nutrient
uptake or yield and the amount of nutrient extracted by a particular soil test method. Soil test
critical concentration is defined as the concentration of an extractable nutrient above which a crop
response to the added nutrient would not be expected. Soil test interpretation is defined as the pro-
cess of developing nutrient application recommendations from soil test concentration and other
soil, crop, economic, environmental, and climatic information. Based on the above discussion, a
Lowland rice
300 mg N kg
-1
BRA 051135
0 mg N kg
-1
FIGURE 3.21
Root growth of lowland rice genotype BRA 051135 at low and high N levels. Half of the N
was applied at sowing and the remaining half at the active tillering growth stage.
