Yoshida - 1981 - Fundamentals of Rice Crop Science

MINERAL NUTRITION OF RICE 121
Table 3.5. Composition of soil solution. a
Concn (ppm)
Growth
stage NH 4 –N P 2 O 5 K 2 O CaO SO 3
Tillering 54 1.4 100 370 672
Panicle
initiation 8.0 1.1 62 375 412
Heading 0.2 trace 19 295 384
a Data were taken from No. 5 plots on 11 Jun, 14 Jul, and 15 Aug in
Table 2 (Tanaka 1961b).
Thus, mass-flow alone can account for the amount of potassium needed for normal
growth.
The relative importance of mass-flow and diffusion in the transport of a nutrient
from the soil solution to root surfaces depends on concentrations of that nutrient in
both soil solution and plant tissue. A generalized relationship between the ion
concentration in the soil solution and the concentration within plant tissues is
discussed elsewhere (Barber 1962).
3.3.2. Nutrient concentrations in the soil solution and culture solution
To see how rice grows in soil solution, a solution culture pot was connected to a
soil culture pot so that the leachate in the latter flowed through a drainage hole to
the former (Tanaka 1961b). The solution was cycled twice a day. Rice growth in
the soil culture was normal but that in the culture solution was poor and the plants
appeared to be phosphorus deficient. The chemical composition of the leachate at
three growth stages is shown in Table 3.5, and can be compared with the chemical
Table 3.6. Composition of culture solution. a
Element
Concn of
element in nutrient
solution (ppm)
N
40
P
K
10
40
Ca 40
Mg 40
Mn 0.5
Mo
B
0.05
0.2
Zn 0.01
Cu 0.01
Fe 2
a
Yoshida et al (1976).