Agriculture Reference
In-Depth Information
Avarage of two
soil depths
3000
2000
Y = 1248.41 + 56.6337X - 0.4203X
2
1000
R
2
= 0.7736**.
0
10-20 cm
3000
2000
Y = 1347.17 + 58.6230X - 0.4696X
2
1000
R
2
= 0.7391**.
0
0-10 cm
3000
2000
Y = 1173.82 + 54.2814X - 0.3709X
2
1000
R
2
= 0.7956**.
0
0
20
40
60
80
Base saturation (%)
FIGURE 8.3
Relationship between base saturation and grain yield of dry bean. (From Fageria, N. K. 2008.
Commun. Soil Sci. Plant Anal.
39:845-857. With permission.)
In addition, in Brazil the lime rate is also determined on the basis of base saturation by using the
following formula (Fageria et al., 1990):
Lime rate (Mg ha
−1
) = [CEC (B
2
− B
1
)/TRNP] × df
where CEC is the cation exchange capacity or total exchangeable cations (Ca
2+
, Mg
2+
, K
+
, H
+
+ Al
3+
)
in cmol
c
kg
−1
, B
2
is the desired optimum base saturation, B
1
is the existing base saturation, TRNP is
the total relative neutralizing power of the liming material, and df is the depth factor, 1 for 20 cm
depth and 1.5 for 30 cm depth.
For Brazilian Oxisols, the desired optimum base saturation for most cereals is in the range of
50-60%, and for legumes it is in the range of 60-70% (Fageria et al., 1990). However, there may