Table 3 Soil quality indicators, scoring function values, and references used for evaluating the soil quality indices in Kersa sub-watershed
From: Soil quality evaluation under different land use types in Kersa sub-watershed, eastern Ethiopia
Source of limits | Scoring curve | Threshold lower Upper | baseline | Optimum | Slope at baseline | Source of Threshold | |
|---|---|---|---|---|---|---|---|
Clay | More is better | 0 | 30 | 15 | – | 0.266 | Gebreyesus Brhane (2014) |
Sand | Optimum | 0 | 60 | Lo-30 Up-50 | 36 | 0.44 | Gebreyesus Brhane (2014) |
Porosity (%) | Optimum | 20 | 80 | Lo -40 Up- 60 | 50 | 0.1280 | |
Aggregate stability % | More is better | 10 | 60 | 30 | 0.296 | Harris et al. (1996) | |
Bulk density(g/cm3) | Less is better | 1.0 | 2.2 | 1.5 | − 2.62 | Harris et al. (1996) | |
Av.P(mg kg−1) | More is better | 5 | 29 | 15 | 0.433 | Mausbach and Seybold (1998) | |
CEC (cmol + kg−1) | More is better | 6 | 46 | 20 | 0.245 | Gebreyesus Brhane (2014) | |
OC (%) | More is better | 1 | 6.5 | 3.5 | 1.046 | Kay and Angers (1999) | |
pH | Optimum | 4.5 | 9.5 | 6.5 | 5.3 | 1.3012 | |