New Water Management Strategies Redefining Sweet Cherry Production in the USA!

Sentek Sensor Technologies Oregon, USA based distributor, Muddy Duck Consulting are currently involved in a major trial with the Oregon State University looking at deficit irrigation and partial root zone drying strategies for sweet cherries. Muddy Duck Consulting currently service growers in Oregon, Washington State and Northern California with Sentek’s range of solutions.

To aid in this research Roberto Nunez-Elisea, Assistant Professor of Horticulture, Sweet Cherry Program, Oregon State University has been using both Sentek’s EnviroSCAN^® and Diviner 2000^® to help to visualize the dynamics of the crop-water-soil atmosphere interactions into easy to understand graphs that they can use to manage their day-to-day irrigation, save water and increase their crop quality and yield.

Most sweet cherry orchards in the Mid-Columbia area of Oregon, USA are established on Mazzard rootstock, which produces good fruit size and yields, but has the disadvantage of producing large trees that require a long establishment period before first fruiting.  With standard rootstocks such as Mazzard, specific ways of controlling excessive vigour and increasing precocity need to be developed.  Strategies of reduced water supply have been shown to successfully achieve this in grapevines and other tree crops.  This research undertaken by Roberto Nunez-Elisea and the Oregon State University evaluates the potential of regulated deficit irrigation and partial root zone drying in reducing the tree vigour and promoting precocity of “Lapins” trees grafted onto Mazzard rootstock.

The Trial Site

The University’s trial is taking place at the Mid-Columbia Agricultural Research Center, in the Hood River, Oregon. The Hood River Valley is one of the nation's agricultural showpieces, renowned for its high quality sweet cherry, pear and apple production. Sweet cherries on over 7500 acres are grown for fresh market, mostly export to Asia and for processing. Bing is the major fresh market variety and Royal Ann (Napoleon) is the major processing variety. The trend is to increase fresh market production with plantings of the newer varieties Chelan, Tieton, Lapins and Sweetheart.

The Trial

Deficit irrigation consists of applying sub-optimal amounts of water to trees to impose a controlled stress.  Trees were watered to replace 100% of total weekly evaporation, 50% of total weekly evaporation and 25% of total weekly evaporation.  Measurements of tree vigour and tree water stress were made just prior to each irrigation cycle.  Soil water content was measured using Sentek’s portable Diviner 2000^® probe as well as their permanent, continuous soil moisture monitoring system, the EnviroSCAN^® throughout the trial site. 

EnviroSCAN^®

Sentek’s flagship product, EnviroSCAN^® has become the most widely used continuously logging, irrigation management tool in Australia. The EnviroSCAN^® is a complete and standalone soil moisture monitoring solution. The data obtained by the EnviroSCAN^® sensors is collected by a central logger and then downloaded by the grower by a variety of telemetry methods.  The IrriMAX^® 5.0 software program converts this information into graphical form to give growers a better understanding of moisture levels in the soil profile

EnviroSCAN

Diviner 2000^®

The Diviner 2000^® is Sentek’s portable soil moisture monitoring solution. Diviner 2000^® is a cost-effective tool for growers that utilises the same award winning technology as the EnviroSCAN^®. The Diviner 2000^® consists of a probe and display unit and has the ability to monitor up to 99 different sites and allows for instant on-field decision making. The patented ‘Swipe and Go^TM’ technology means that the Diviner 2000^® does not need to be held at each depth in the soil profile. To take a reading the encapsulated capacitance sensor is simply swiped in and out of the access tube, measuring up to 16 depths in just a few seconds. 

 Results

Initial results have shown that deficit treatments have reduced vegetative vigour, a primary aim of this trial.  Further work is being carried out during 2003 to identify periods of reduced fruit growth, where the impact of water stress on fruit size is considerably reduced.   It has been determined that water stress during the final stage of cell expansion should be avoided, because adequate water is required for maximizing fruit size.

Partial root zone drying (PRD) has been developed for grapevines in Australia, and consists of periodically shifting irrigation from one side of the tree root system to the other.  Non-irrigated roots in a drying condition produce a biochemical signal that acts as a natural growth retardant.  The research in Oregon to date has focused on characterising the wetting pattern of drippers in the soil and determining the interval needed to switch irrigation from one side of the system to the other.  The EnviroSCAN^® and Diviner 2000^® systems measuring soil water content have been integral to this research.  They have shown that drippers placed 50 cm from the trunk will saturate the soil on one side of the root system while the other side remains dry, allowing for application of PRD treatments.  The results of PRD on tree growth for the 2003 are still preliminary.

Monitoring soil water content in commercial orchards

In addition to the research conducted on new irrigation management strategies for sweet cherry, projects involving soil water monitoring in commercial sweet cherry and pear orchards were initiated both in the Hood River Valley and The Dalles during 2003. EnviroSCAN® systems and Diviner 2000® access tubes have been installed in several commercial plantings to show growers how their irrigation practices impact soil water dynamics and tree water use. It is anticipated that these new monitoring tools will result in more efficient irrigation management and considerable water savings in commercial fruit production

Probe Grower