Table 1 Indicators and their selected criteria for the preparation of Soil Health Card (SHC) according to Northern Rivers Soil Health Card (NRSHC) (2002) based on USDA
Soil quality indicators | Poor (score 1, 2) | Medium (score 3, 4) | Good (score 5, 6) |
|---|---|---|---|
Soil structure | A large no. of clods found, very poor granular structure | Few clods found, irregular granular structure | No clods found, good granular and crumb structure present |
Subsurface compaction | Tightly bonded layers, Interlayer lines cannot be identified easily, a lot of turbulent mixing found | Firm soil, interlayer lines are visible with small turbulent mixing | Loose soil, Interlayer lines can be distinguished easily |
Aggregate stability | Aggregate took more than 5Â min to break | Aggregate broke apart within 2Â min | Aggregate broke apart within 1Â min |
Ground cover | Less than 40% | 40–60% | More than 60% |
Soil smell | Highly stagnant muddy smell identified | Little earthy or no smell identified | Fresh earthy smell identified |
Soil pH | Less than 5 | 5–5.5 | 5.6–8 |
Organic matter and soil color | Topsoil is light brown in color; color is getting lighter with increasing depth. OM is irrecoverable or can be recovered after a lot of managements | Topsoil is normal brown in color with irregular sign of black portion. OM can be recovered easily | Topsoil and subsoil both are black/deep brown in color |
Drainage capacity | Soils drain and dry very slowly; fields remain water logged after simple rain | Soils drain and dry slowly; fields’ remains water logged only after heavy rains | Soils drain and dry very quickly; fields remain as usual even after heavy rains |
Diversity of macro life | Less than 3 varieties found in naked eye | 3–6 varieties found naked eye | More than 6 varieties found in naked eye |
Roots and residues | Roots are found only in top soil, no visible residue decomposition found | Roots are found within 8Â cm below the surface, little residue decomposition found | Roots are found more than 8Â cm below the surface, noticeable residue decomposition found |
Earthworm content | Less than 3 in number present | 3–6 in number present | More than 6 in number present |
Infiltration rate | It takes more than 5 min to infiltrate or no infiltration occurs | It takes 3–5 min to infiltrate | It takes 1–2 min to infiltrate |
Soil aeration | No available aeration chance. Soil grains are packed tightly | Moderate permeability chance for air. Inter-granular space is visible | Efficient aeration is possible. Soil has available spaces between two grains |
Seedling emergence | Seedlings are irregular in size | Seedlings of each cluster are even in size | Almost all seedlings are even in size |
Crop coverage and leaf color | Poor crop growth, yellow/purple/light green in color | Moderate crop growth, green in color | Healthy crop growth, dark green in color |