Omahu

1 - Omahu

Soil Properties

Parent material	Water deposit (alluvium) from greywacke and/or sandstone
Characteristic site and soil features	Main channel and active flood plain of Ngaruroro until 1867: gravelly and stony soils with less than 30cm of sand to loamy fine sand on top but with sand lenses at depth in gravels
Associated soils not shown within map unit at map scale but separated out in more detailed maps. - Sample Location	3, 4, H
Natural drainage and depth to water table after wet periods	Good >60cm
Potential rooting depth, texture, and limiting layer for most crops. for grapes	1, <10cm sand on stony gravels  1a, 10-15cm loamy f. sand on f. sand on stony gravels 1b, 15-30cm loamy f. sand on f. sand on stony gravels  all have sand lenses at depth all- >100cm
Available water capacity (AWC) for grapes	1, 5-8mm 1a, 8-12mm 1b, 12-28mm all, 28-50mm
Infiltration rate	1, very rapid 1a, rapid 1b, rapid
Permeability rate	Stony gravels - very rapid Sand lenses - moderate or rapid
Susceptibility to wind erosion when dry	All, very high
Unfavourable soil characteristics	All, sand topsoil susceptible to wind erosion very low AWC very rapid permeability 1, many gravels at surface very rapid infiltration 1a, rapid infiltration 1b, rapid infiltration

 

Soil Management

Artificial drainage	1, 1a, 1b none required
Cultivate when moist to avoid: wind erosion	1, 1a, 1b
Irrigation:- Recommended method Dripper spacing for continuous wetted strip Amount and frequency	1, 1a, 1b, sprinkler to prevent water loss 1, 30cm if 4 l/hr drippers used 1a, 1b, 30cm if 4 l/hr drippers used 1, 1a, 1b, little and often to prevent water loss for shallow rooting plants - 2.5-7.5mm 1, 2.5-4mm 1a, 4-6mm 1b, 6-14mm for grapes, 7-15mm

 
Omahu Stony Gravel (photo E. Griffiths)