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Campania BD dataset: Number of samples (n), mean and standard deviation (st. dev.) of measured BD values in each land system class. Mean, standard deviation of BD values predicted by all 63 PTFs. Lowest RMSE and highest R? values related for the best PTF found for each land system class are reported.

Table 9 Campania BD dataset: Number of samples (n), mean and standard deviation (st. dev.) of measured BD values in each land system class. Mean, standard deviation of BD values predicted by all 63 PTFs. Lowest RMSE and highest R? values related for the best PTF found for each land system class are reported.

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Fig. 1. Land system classes in Campania Region (Di Gennaro et al., 2002).
Fig. 1. Land system classes in Campania Region (Di Gennaro et al., 2002).
Description of land system classes in Campania. Table 1
Description of land system classes in Campania. Table 1
Description of soil groups in the Province of Naples. Table 2
Description of soil groups in the Province of Naples. Table 2
Fig. 2. Soil groups in the Province of Napoli (Di Gennaro and Terribile, 1999).
Fig. 2. Soil groups in the Province of Napoli (Di Gennaro and Terribile, 1999).
Fig. 3. Soil sampling positions in the topsoil (3316 green circles on the left map) and in the subsoil (500 red circles on the right map) of the Campania regional dataset.
Fig. 3. Soil sampling positions in the topsoil (3316 green circles on the left map) and in the subsoil (500 red circles on the right map) of the Campania regional dataset.
Descriptive statistics of the soil size class (Sa, Si, and Cl), soil organic carbon (OC) content, and oven-dry bulk density (BD) for the 3316 topsoil samples in Campania. Table 4 Table 3
Descriptive statistics of the soil size class (Sa, Si, and Cl), soil organic carbon (OC) content, and oven-dry bulk density (BD) for the 3316 topsoil samples in Campania. Table 4 Table 3
Descriptive statistics of the soil size class (Sa, Si, and Cl) and oven-dry bulk density (BD) for the 500 subsoil samples in Campania.
Descriptive statistics of the soil size class (Sa, Si, and Cl) and oven-dry bulk density (BD) for the 500 subsoil samples in Campania.
ig. 4. Distribution of soil bulk density values in the USDA texture triangle for Campania region (CR) dataset (left triangle) and Upper Alento River Catchment (UARC) database (rig riangle). Although the PTF proposed by Adams (1973) performances poorly (RMSE = 0.445 g cm~?), the PTFs derived from it, namely Nanko et al. ee EE: EAMETS = SNUG ge. Muxatvasreeewe: BP en eT Teter ear XN The correlation coefficients observed in the Tibetan Plateau in China by Qiao et al. (2019) are r = —0.165, r = —0.236, r = +0.330, r = —0.258 with Sa, Si, Cl, and OC, respectively. Therefore, they observed that BD was positively correlated with Cl (and depth), and negatively
ig. 4. Distribution of soil bulk density values in the USDA texture triangle for Campania region (CR) dataset (left triangle) and Upper Alento River Catchment (UARC) database (rig riangle). Although the PTF proposed by Adams (1973) performances poorly (RMSE = 0.445 g cm~?), the PTFs derived from it, namely Nanko et al. ee EE: EAMETS = SNUG ge. Muxatvasreeewe: BP en eT Teter ear XN The correlation coefficients observed in the Tibetan Plateau in China by Qiao et al. (2019) are r = —0.165, r = —0.236, r = +0.330, r = —0.258 with Sa, Si, Cl, and OC, respectively. Therefore, they observed that BD was positively correlated with Cl (and depth), and negatively
Descriptive statistics of the percentage of soil size class (Sa, Si, and Cl) and organic carbon (OC), and of oven-dry soil bulk density (BD) for the 105 soil samples taken in the UARC. are displayed in Fig. 5 and range between 0.196 g cm~? (Song et al., 2005) and 0.461 g cm~? (Kaur et al., 2002).
Descriptive statistics of the percentage of soil size class (Sa, Si, and Cl) and organic carbon (OC), and of oven-dry soil bulk density (BD) for the 105 soil samples taken in the UARC. are displayed in Fig. 5 and range between 0.196 g cm~? (Song et al., 2005) and 0.461 g cm~? (Kaur et al., 2002).
List of the 63 published PTFs with references, equations and number of soil samples (n).
List of the 63 published PTFs with references, equations and number of soil samples (n).
Fig. 5. Statistical performance of the existing 63 PTFs in terms of RMSE-values. PTFs are reported in alphabetical order.
Fig. 5. Statistical performance of the existing 63 PTFs in terms of RMSE-values. PTFs are reported in alphabetical order.
Minimum and maximum RMSE values reported for 6 published PTFs with references and number of soil samples (n).
Minimum and maximum RMSE values reported for 6 published PTFs with references and number of soil samples (n).
Pearson's linear correlation coefficients (r) and associated p-values between soil bulk density (BD) and percentages of sand (Sa), silt (Si), clay (Cl), and soil organic carbon (OC), together with the mathematical transformations of OC namely log1o(OC), (OC)°°, (OC)~', and exp.(OC) employed in the 63 PTFs.
Pearson's linear correlation coefficients (r) and associated p-values between soil bulk density (BD) and percentages of sand (Sa), silt (Si), clay (Cl), and soil organic carbon (OC), together with the mathematical transformations of OC namely log1o(OC), (OC)°°, (OC)~', and exp.(OC) employed in the 63 PTFs.
Fig. 6. Statistical performances of 63 existing PTFs for predicting soil bulk density values grouped according to 30 land systems classes in Campania. The 63 R?-values (referred to the primary y-axis) in each class are reported in the box plots and compared to the best R? (horizontal red dashed line) obtained with the PTF of Leonaviciute (2000). The best RMSE value (referred to the secondary y-axis) in each class (green solid line) is compared to the best RMSE value (horizontal green dashed line) obtained with the PTF of Song et al. (2005). The number of soil samples in each soil group is reported at the top of the plot frame.
Fig. 6. Statistical performances of 63 existing PTFs for predicting soil bulk density values grouped according to 30 land systems classes in Campania. The 63 R?-values (referred to the primary y-axis) in each class are reported in the box plots and compared to the best R? (horizontal red dashed line) obtained with the PTF of Leonaviciute (2000). The best RMSE value (referred to the secondary y-axis) in each class (green solid line) is compared to the best RMSE value (horizontal green dashed line) obtained with the PTF of Song et al. (2005). The number of soil samples in each soil group is reported at the top of the plot frame.
Fig. 7. Statistical performances of 63 existing PTFs for predicting soil bulk density values grouped according to 23 soil groups in the Province of Naples. Ten groups (A1, A4, B4, E1, E3, F1, F3 G1, I, 12) are not showed for lack of data (see Table A.2 in the Appendix). The 63 R?-values (referred to the primary y-axis) are reported in the box plots and compared to the best R? (horizontal red dashed line) obtained with the PTF of Leonaviciute (2000). The best RMSE value (referred to the secondary y-axis) in each group (green solid line) is compared to the best RMSE value (horizontal green dashed line) obtained with the PTF of Song et al. (2005). The number of soil samples for each soil group is reported at the top of the plot frame.
Fig. 7. Statistical performances of 63 existing PTFs for predicting soil bulk density values grouped according to 23 soil groups in the Province of Naples. Ten groups (A1, A4, B4, E1, E3, F1, F3 G1, I, 12) are not showed for lack of data (see Table A.2 in the Appendix). The 63 R?-values (referred to the primary y-axis) are reported in the box plots and compared to the best R? (horizontal red dashed line) obtained with the PTF of Leonaviciute (2000). The best RMSE value (referred to the secondary y-axis) in each group (green solid line) is compared to the best RMSE value (horizontal green dashed line) obtained with the PTF of Song et al. (2005). The number of soil samples for each soil group is reported at the top of the plot frame.
Soil-landscape units of the Upper Alento River Catchment Fig. 8. Statistical performances of the 63 existing PTFs for predicting soil bulk density values grouped according to soil-landscape units (VAG and MIX) in Upper Alento River Catchment (UARC). The 63 R?-values (referred to the primary y-axis) are reported in the box plots and compared to the best R? (horizontal red dashed line) obtained with the PTF of Leonaviciute (2000). The best RMSE value (referred to the secondary y-axis) in each unit (green asterisks) is compared to the best RMSE value (horizontal green dashed line) obtained with the PTF of Song et al. (2005). The number of soil samples for each soil group is reported at the top of the plot frame.
Soil-landscape units of the Upper Alento River Catchment Fig. 8. Statistical performances of the 63 existing PTFs for predicting soil bulk density values grouped according to soil-landscape units (VAG and MIX) in Upper Alento River Catchment (UARC). The 63 R?-values (referred to the primary y-axis) are reported in the box plots and compared to the best R? (horizontal red dashed line) obtained with the PTF of Leonaviciute (2000). The best RMSE value (referred to the secondary y-axis) in each unit (green asterisks) is compared to the best RMSE value (horizontal green dashed line) obtained with the PTF of Song et al. (2005). The number of soil samples for each soil group is reported at the top of the plot frame.
Fig. 9. Comparison between measured and predicted soil bulk density values for soil- landscape unit VAG in the Upper Alento River Catchment (UARC). The predicted BD- values refer to the “best” PTF (Al-Qinna and Jaber, 2013).
Fig. 9. Comparison between measured and predicted soil bulk density values for soil- landscape unit VAG in the Upper Alento River Catchment (UARC). The predicted BD- values refer to the “best” PTF (Al-Qinna and Jaber, 2013).
Table A.1 (continued)
Table A.1 (continued)
BD dataset in the Province of Naples: Number of samples (n), mean and standard deviation (st. dev.) of measured BD values in each soil group. Mean, standard deviation of BD values predicted by all 63 PTFs. Lowest RMSE and highest R? values related for the best PTF found for each soil group are reported.
BD dataset in the Province of Naples: Number of samples (n), mean and standard deviation (st. dev.) of measured BD values in each soil group. Mean, standard deviation of BD values predicted by all 63 PTFs. Lowest RMSE and highest R? values related for the best PTF found for each soil group are reported.
Related topics:
Soil PhysicsSurveying and MappingPedotransfers FunctionsSoils and Landscapes
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