Omarama Station recently played host to the "Legumes in the High Country" field day, organised by Lincoln
University and Beef + Lamb NZ. There was a good turnout of farmers and industry
professionals to the farm owned and run by Richard and Annabelle
Subtil, 2015 winners of the South Island Farmer of the Year competition. The focus for the day was the use of legume species in the high
country environment with a short session on the use of irrigation and soil moisture monitoring in the arid environment that is the Mackenzie Country.
 |
| Omarama Station (Courtesty of Richard Subtil) |
Dr MS Srinivasan from NIWA gave the first presentation for the day at
the site of the lysimeter that has recently been installed on the station. The
lysimeter is the first in the Waitaki catchment and aims to build knowledge
around drainage and soil water under the developing soils at Omarama Station. The site contains
three catchment sleeves one of which has soil moisture sensors installed. Any drainage
water from the site is measured which gives an indication of the soil moisture
status and how drainage from the soil profile is taking place.
From a soil moisture point of view the lysimeter is
important as the soils at Omarama Station have exceptionally variable fertility, structure
and water holding capacity. Irrigation is not new to the area however the shift
from border-dyke irrigation to more efficient spray irrigation has seen a
massive change in the water use efficiency on extensive properties such as
Omarama Station. Soil development under irrigation is an interesting concept and soils mapped on Omarama Station have shown to have varying levels of water
holding capacity based on how long they have been irrigated for in the past. Investigation
has shown that the depth of soil and the water holding capacity has improved
under 30 years of irrigation.
 |
| Irrigation at Omarama Station (Courtesy of Richard Subtil) |
Agri Optics has installed three sub-surface AquaCheck probes that will
complement the work being undertaken at the lysimeter site. This information will flow into
the decision making process that is used around timing and quantity of irrigation
water applied by the team at Omarama Station.
Derrick Moot spoke on how selection of species was important to maximising water use efficiency in moisture deficient environments such as the Mackenzie Basin. As we know lucerne is a great fit into dryland high country systems.
It has the ability to maximise the water use efficiency and has a high water to
dry matter conversion ratio (kg DM/mm/ha). The selection of species going forward and the development of novel species all points towards maximising the efficiency of water use in dry high country areas.
Write up by Nick Evans
