Agriculture Reference
In-Depth Information
TABLE 3.11
Relationship between Lime Rate (X) and Nutrient Uptake (Y) in Soybean
Shoot and Grain
Regression Equation
Nutrient
Shoot
R
2
N (kg ha
−1
)
Y = 36.2499 − 0.8188X + 0.0701X
2
0.2216
NS
P (kg ha
−1
)
Y = 1.6261 + 0.0069X − 0.0013 X
2
0.4067*
K (kg ha
−1
)
Y = 49.6413 + 1.2491X − 0.0076 X
2
0.4241*
Ca (kg ha
−1
)
Y = 21.8085 + 1.3067X − 0.0183X
2
0.5869**
Mg (kg ha
−1
)
Y = 13.5985 + 0.7763X − 0.0148X
2
0.4531**
Grain
N (kg ha
−1
)
Y = 195.6751 + 15.8686X − 0.5951X
2
0.7462**
P (kg ha
−1
)
Y = 9.8974 + 0.8371X − 0.0253X
2
0.8073**
K (kg ha
−1
)
Y = 53.2387 + 4.8377X − 0.1917X
2
0.7491**
0.3768**
Ca (kg ha
−1
)
Y = 8.8891 + 0.8883X − 0.0408X
2
0.7985**
Mg (kg ha
−1
)
Y = 6.8257 + 0.7184X − 0.0290X
2
Source:
From Fageria, N. K. et al. 2013b.
Commun. Soil Sci. Plant Anal
. 44:2941-2951. With
permission.
*,**, NS: Significant at the 5% and 1% probability levels and nonsignificant, respectively.
3.4.3 f
orms
of
n
ItroGen
u
ptake
BY
p
lants
Nitrogen is mainly absorbed as
NO
3
−
and
NH
4
+
by the roots. In oxidized soils,
NO
3
−
is the dominant
form of N uptake, since ammonium is quickly transformed in the soil solution to nitrate through
nitrification when typical weather conditions for crop growth prevail. Crop plants absorb nitrate
through their roots and transport it directly to the leaves in the transpiration stream. Once in the
leaf, nitrate is reduced to ammonium and combines with organic acids to form amino acids and
proteins (Gerik et al., 1998). These processes require considerable energy in the form of reductants,
such as nicotinamide adenine dinucleotide (NADH), and a ready supply of organic acids from
carbon assimilation. Up to 55% of the net carbon assimilated in some tissues is committed to N
metabolism (Huppe and Turpin, 1994).
TABLE 3.12
Relationship between Nutrient Uptake (X) in the Grain and Yield (Y)
of Soybean
Nutrient
Regression Equation
R
2
Nitrogen
Y = −1281.9460 + 23.9024X − 0.0308X
2
0.8901**
Phosphorus
Y = −1688.9170 + 547.4529X − 15.5759X
2
0.9126**
Potassium
Y = −1588.2320 + 97.2274X − 0.4910X
2
0.8630**
Calcium
Y = −1290.9050 + 597.0891X − 20.2308X
2
0.6131**
Magnesium
0.7921**
Y = 3208.7790 − 385.0645X + 34.6338X
2
Source:
From Fageria, N. K. et al. 2013b.
Commun. Soil Sci. Plant Anal
. 44:2941-2951. With permission.
**Significant at the 1% probability level.
