Victorian Resources Online (archived)
NE42a
| Property: Rutherglen Research Institute | Location: Rutherglen |
Soil Profile Morphology:
Surface Soil
| A1 | 0-5 cm | Yellowish brown (10YR5/4); fine sandy loam; very firm consistence dry: |
| A2 | 5-35 cm | Light yellowish brown (10YR6/4) with a very pale brown (10YR8/2) bleach?; fine sandy loam; firm consistence dry; pH 6.2; abrupt change to: |
| Subsoil | ||
| B1 | 35-45 cm | Light yellowish brown (10YR6/4) with yellow (10YR7/8) mottles; fine sandy clay loam (with quartz grit); weak consistence slightly moist; pH 6.4: |
| B21 | 45-55 cm | Very pale brown (10YR7/4) with yellow (10YR7/6) mottles; light medium clay; very firm consistence slightly moist; contains ferromanganiferous nodules; pH 6.4: |
| B22 | 55+ cm | Light yellowish brown (10YR6/4) with dark red (2.5YR4/8) mottles; clay loam (with quartz grit); weak consistence slightly moist; contains a few (5-10 %) ferromanganiferous nodules (up to 2 cm in size); pH 6.5. |
Key Profile Features:
- Strong texture contrast between surface (A2) horizon (9% clay) and the sodic subsoil (B21) horizon (27% clay).
- Accumulation of ferromanganiferous nodules throughout the subsoil.
Horizon | pH | Salinity Rating | ||
Surface (A2 horizon) | Slightly Acid | Very Low | Sodic | None (sl r/m) |
Subsoil (B1 horizon) | Slightly Acid | Very Low | Sodic | None (modr/m) |
Deeper subsoil (at 55+ cm) | Slightly Acid | Very Low | Sodic | None |
Management Considerations:
Whole Profile
- The inherent fertility is very low throughout the profile. Planting legumes (if the pH is suitable) will help to increase the fertility levels.
- The surface soil has a high fine sand content (52%). When cultivated in a dry condition it will become ‘powdery’ and subsequent rainfall may result in surface sealing occurring. Soils such as these rely to a large extent on organic matter for maintaining aggregation. The levels of organic carbon measured at the pit site (which may or may not be representative of the whole paddock) is quite low. Organic matter levels will build up under pasture but will decline if cropping takes place. Practices such as residue retention, minimum tillage and including pasture rotations could be utilised if cropping takes place in order to build up organic matter, improve aggregation as well as assist in the low water holding capacity and reduce erosion risk.
- The levels of total nitrogen measured at this pit site is very low. However, this is best assessed by taking a bulked sample from across the paddock.
- The very low wilting point value (2.2) of the surface horizon indicates that plants will be able to utilize very light rains when the soil is dry. However, due to the low water storage capacity, plants will soon suffer moisture stress unless further rain falls occur.
- Infiltration will be quite high in the surface soil until it meets the more clayey subsoil.
- The presence of bleaching in the subsurface (A2) horizons indicates that periodic waterlogging occurs above the slowly permeable subsoil.
- The subsoil is sodic with no dispersion due to the acidity and there could be higher than normal alumium levels as well. Moderate dispersion does occur after remoulding and this condition may result in water and root movement being restricted in the subsoil. Deep ripping into the subsoil would help to break up the physical structural problems and the application of gypsum would help to neutralize the chemical sodic problems. This expensive option would firstly depend on expected crop yield and also on adequate rainfall, to wash the gypsum down the deep rips into the subsoil. Gypsum can also be added to the surface without deep ripping, but it would require more time to wash the gypsum down to the subsoil and less of it would probably make it.
- The inherent fertility is moderate in the subsoil due to the high magnesium levels.
- The subsoil is mottled throughout which indicates that there is some waterlogging within these clayey horizons.
