The HBRC soil maps of the Heretaunga Plains show the MicroFarm to be on Twyford silt loam (5 and 5s). However our experience to date suggests the soils are somewhat varied and include areas that tend towards a Hastings silt loam soil.
A 2m pit dug to install a septic tank system found a layer of grey clay at about 90 – 110 cm depth. A soil pit excavated for the 2013 LandWISE Conference found evidence of soil mottling at 40cm. This indicates poor winter drainage, and is thought to be the legacy of previous long term orcharding.
Water Holding Capacity
Elwyn Griffiths handbook, “Soils of the Heretaunga Plains” indicates Total Available Water for Twyford soils of about 10 – 15% by volume. Total Available Water for the Hastings silt loam soil is around 16% by volume and for the Hastings clay loam around 25% by volume. The range is large.
NOTE: In the book the term Available Water Capacity is used. We have used Total Available Water in line with the Irrigation New Zealand Glossary of Terms.
Preliminary soil monitoring by HydroServices identified volumetric Readily Available Water in the upper 200mm rootzone of 18%. This suggests the soils are at the higher end of the expected water holding range.