Research Article

Evaluation of Physicochemical Properties of Sandy-Textured Soils under Smallholder Agricultural Land Use Practices in Sarawak, East Malaysia

Table 4

Surface and subsurface soil physicochemical properties at various agricultural land uses.

Soil physicochemical propertiesSecondary forest (SF)Rubber (R)Oil palm (OP)Pepper (P)
n = 6n = 7n = 9n = 4

Surface soil (0–10 cm)
pHw4.59 ± 0.15a4.53 ± 0.07a4.57 ± 0.14a4.76 ± 0.20a
pHk3.52 ± 0.24a3.59 ± 0.26a3.49 ± 0.18a3.86 ± 0.11a
EC (µS·cm−1)26 ± 3a27 ± 5a38 ± 5b26 ± 7a
Total C (g·kg−1)18.0 ± 3.1a16.3 ± 4.9a19.5 ± 7.3a19.6 ± 4.5a
Total N (g·kg−1)1.20 ± 0.19a0.99 ± 0.34a1.37 ± 0.35a1.30 ± 0.40a
C/N15.1 ± 2.1a16.7 ± 2.0a13.9 ± 2.1a15.4 ± 2.0a
CEC (cmolc·kg−1)4.13 ± 0.56a3.80 ± 0.68a4.42 ± 0.99a4.70 ± 0.68a
Exch. K+ (cmolc·kg−1)0.11 ± 0.01a0.09 ± 0.02a0.08 ± 0.03a0.10 ± 0.02a
Exch. Mg2+ (cmolc·kg−1)0.13 ± 0.03a0.10 ± 0.01a0.13 ± 0.06a0.19 ± 0.10a
Exch. Ca2+ (cmolc·kg−1)0.43 ± 0.10ab0.27 ± 0.04a0.30 ± 0.18ab0.52 ± 0.13b
Exch. Al3+ (cmolc·kg−1)0.46 ± 0.36a0.30 ± 0.16a0.39 ± 0.21a0.55 ± 0.08a
Sum of basesa (cmolc·kg−1)0.70 ± 0.10ab0.49 ± 0.08a0.68 ± 0.23ab0.92 ± 0.32b
Effective CECb (%)1.16 ± 0.34ab0.79 ± 0.21a1.08 ± 0.32ab1.47 ± 0.30b
Al saturationc (%)35.9 ± 18.2a8.3 ± 1.6a35.7 ± 14.2a38.3 ± 8.4a
Available P (mg·kg−1)3.7 ± 2.0a8.3 ± 1.6a19.4 ± 10.6a65.9 ± 29.7b
Clay (%)15.9 ± 7.9a10.0 ± 2.3a11.1 ± 4.6a13.8 ± 1.8a
Silt (%)11.9 ± 2.0a9.3 ± 4.4a10.8 ± 9.1a13.2 ± 7.6a
Sand (%)72.2 ± 8.4a80.7 ± 5.7a78.1 ± 7.9a73.0 ± 7.0a
Bulk density (g·mL−1)1.05 ± 0.10a1.09 ± 0.16ab1.23 ± 0.07ab1.26 ± 0.06b
Hardnessd (mm)12 ± 4a13 ± 2a15 ± 1a20 ± 3b

Subsurface soil (30–40 cm)
pHw4.95 ± 0.21ab5.07 ± 0.19ab5.19 ± 0.10b4.83 ± 0.23a
pHk3.94 ± 0.20ab4.29 ± 0.18b4.00 ± 0.24ab3.83 ± 0.32a
EC (µS·cm−1)11 ± 2a12 ± 2a12 ± 2a23 ± 7b
Total C (g·kg−1)6.8 ± 3.1a12.3 ± 5.7a8.4 ± 4.1a10.6 ± 1.4a
Total N (g·kg−1)0.40 ± 0.14a0.48 ± 0.15a0.54 ± 0.14a0.46 ± 0.10a
C/N16.6 ± 4.8a25.1 ± 6.0a15.4 ± 5.3a23.8 ± 6.7a
CEC (cmolc·kg−1)1.67 ± 0.83a1.91 ± 0.56a1.82 ± 0.71a2.00 ± 0.69a
Exch. K+ (cmolc·kg−1)0.02 ± 0.01a0.02 ± 0.01a0.02 ± 0.01a0.04 ± 0.02a
Exch. Mg2+ (cmolc·kg−1)0.08 ± 0.02b0.06 ± 0.02ab0.04 ± 0.03a0.07 ± 0.01ab
Exch. Ca2+ (cmolc·kg−1)0.28 ± 0.01ab0.24 ± 0.03ab0.19 ± 0.07a0.36 ± 0.16b
Exch. Al3+ (cmolc·kg−1)0.49 ± 0.36a0.37 ± 0.20a0.43 ± 0.20a0.60 ± 0.17a
Sum of basesa (cmolc·kg−1)0.48 ± 0.03ab0.37 ± 0.05ab0.30 ± 0.13a0.51 ± 0.17b
Effective CECb (%)0.96 ± 0.37a0.74 ± 0.23a0.73 ± 0.18a1.10 ± 0.26a
Al saturationc (%)44.3 ± 18.9a47.0 ± 12.4a57.5 ± 20.0a53.9 ± 11.3a
Available P (mg·kg−1)1.4 ± 1.0a6.2 ± 3.1b3.1 ± 1.6ab4.3 ± 2.0ab
Clay (%)13.6 ± 8.8a11.8 ± 4.1a13.1 ± 5.5a15.2 ± 3.8a
Silt (%)16.6 ± 3.2ab10.2 ± 3.7a13.0 ± 7.3ab22.4 ± 9.7b
Sand (%)69.8 ± 9.5ab78.0 ± 6.3b73.9 ± 7.9ab62.5 ± 9.2a
Bulk density (g·mL−1)1.64 ± 0.09a1.47 ± 0.15a1.56 ± 0.12a1.55 ± 0.07a
Hardnessd (mm)17 ± 2a18 ± 2a20 ± 2a19 ± 1a

Values are means ± standard deviation; values in the same row followed by different letters indicate significant differences at 5% levels using Scheffe’s multiple comparison test. aSum of exchangeable K+, Mg2+, Ca2+, and Na+; bsum of exchangeable bases and exchangeable Al; cexchangeable Al in percent of ECEC; dmeasured using Yamanaka-type push cone penetrometer.