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increase was 5.1-7.4 in the lime rate range of 0-18 Mg ha −1 . The increase in pH with lime applica-
tion was associated with a neutralization of Al + H ions and an increase in Ca and Mg concentra-
tion in the soil solution. Fageria and Stone (2004) and Fageria (2006) reported a similar increase in
pH with the application of lime in the range of 0-24 Mg ha −1 in the Brazilian Oxisol. Overall, the
increase in base saturation was 16.4-91.5%, H + Al decrease was 3.88-0.43 cmol c kg −1 , Al decrease
was 1.52-0 cmol c kg −1 , Ca increase was 0.45-3.14 cmol c kg −1 , Mg increase was 0.19-1.32 cmol c kg −1 ,
and cation exchange capacity increase was 4.64-5.01 cmol c kg −1 with the application of 0-18 Mg
lime ha −1 . Fageria and Stone (2004) reported a similar increase or decrease in the acidity indices
of Brazilian Oxisol with the application of lime in the range of 0-24 Mg ha −1 . Fageria (2001a) also
reported similar increases in Ca and Mg concentration Brazilian Oxisol with the application of lime
in the range of 0-20 Mg ha −1 .
An interesting feature of these results is that, with the application of 3 Mg lime ha −1 , practically
all the Al 3+ ions were neutralized. This means that acidity at a higher lime rate was represented by
H + ions in the soil solution. Fageria and Morais (1987) reported similar results with the application
of lime in the Brazilian Oxisol. Soil acidity indices (pH, Ca, Mg, base saturation, H + Al, acidity
saturation, Ca/K, and Mg/K) were having a significant quadratic association with grain yield (Table
3.19). The variability in grain yield was 93% due to soil pH, 96% due to the soil Ca content, 94%
due to the soil Mg content, 97% due to base saturation, 91% due to the H + Al content, 94% due to
acidity saturation, 89% due to the Ca/Mg ratio, 90% due to the Ca/K ratio, and 91% due to the Mg/K
ratio (Table 3.19). This means that the importance of acidity indices in increasing soybean yield was
in the order of base saturation > Ca > Mg > acidity saturation > pH > Mg/K > H + Al > Ca/K > Ca/
Mg. Fageria (2001b) reported a more or less similar importance of increasing soybean grain yield
in Brazilian Oxisol.
Values for maximum grain yield (3100 kg ha −1 ) calculated by quadratic regression equations were
7.1 for pH, 2.7 comol c kg −1 for Ca, 1.6 comol c kg −1 for Mg, 88% for base saturation, 0.49 comol c kg −1
for H + Al, 5.2 cmol c kg −1 for CEC, 1.92 Ca/Mg ratio, 9.5 Ca/K ratio, and 5.4 Mg/K ratio. Fageria
(2001b) reported that the maximum grain yield of soybean in Brazilian Oxisol was obtained with
63% base saturation and at a pH of 6.8. The Ca and Mg values for maximum grain yield of soybean
TABLE 3.19
Relationship between Soil Chemical Property (X) and Soybean Grain Yield
Soil Property
Regression Equation
R 2
VMY a
VMEY b
pH in H 2 O
Y = −9884.7040 + 3636.8190X − 254.6528X 2
0.9260**
7.1
6.0
Ca (comol c kg −1 )
Y = 1484.3560 + 1189.5530X − 216.6682X 2
0.9577**
2.7
1.6
Mg (comol c kg −1 )
Y = 1650.7640 + 1881.7360X − 584.0436X 2
0.9362**
1.6
0.9
Base saturation (%)
Y = 1397.4520 + 38.7096X − 0.2203X 2
0.9713**
88
51.0
H + Al (comol c kg −1 )
Y = 3080.3400 + 93.4309X − 95.7709X 2
0.9076**
0.49
0
Acidity saturation (%)
Y = 3041.1380 + 11.3545X − 0.5417X 2
0.9409**
10.5
0
CEC (cmol c kg −1 )
Y = −42,520.15 + 17,455.66X −1670.3430X 2
0.5101**
5.2
4.8
Ca/Mg ratio
Y = 5359.008 − 2288.174X + 281.131X 2
0.8903**
1.92
1.9
Ca/K ratio
Y = 1277.9740 + 397.1924X − 20.9609X 2
0.9006**
9.5
5.6
Mg/K
0.9124**
5.4
3.0
Y = 1599.9570 + 573.1361X − 52.9977X 2
Source: From Fageria, N. K. et al. 2013b. Commun. Soil Sci. Plant Anal . 44: 2941-2951. With permission.
Note: Values are averages of three crops.
a VMY = value of maximum yield was calculated by a quadratic regression equation.
b VMEY = value of maximum economic yield was calculated by a regression equation on the basis of 90% of the maximum
yield.
**Significant at the 1% probability level.
 
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