In your Review article “Agriculture group requests RDOS compostable material funding” Thursday, April 12, it was reported that I had said, “By using compost we can rid ourselves of commercial fertilizers.”
This has resulted in my having to explain myself to some confused grower friends. The intension was to indicate that the compost could replace a specific phosphorus application used to stimulate feeder root development but not all fertilizer use. The following should clarify my intent.
In the 2011 RDOS study “Utilization of compost for Treatment of Crop Roots” supported by the Agriculture Environment and Wildlife Fund, I investigated the impact of compost from OK Falls on the fruit Quality improvement that was reported by Dr. Peter Toivonen a researcher at PARC.
A presentation was made to the Regional District Board requesting further support to expand the study in 2012. It appears that one of my comments was not clear. I did not intend to imply that the compost would replace commercial fertilizers as a general statement but indicated that the compost treatment duplicated the action of certain phosphorus treatments used to stimulate feeder root development. Using a compost application would eliminate the routine application of a soluble-phosphorus treatment in spring that many Okanagan/Similkameen growers currently apply.
In addition I observed, during my root observations, that feeder root die-back was greatly reduced or eliminated in root systems treated with compost. This was a very important find. Where phosphorus is used as a feeder route stimulant die-back is common and should be addressed separately. The fact that government regulators have not given growers the tools to deal with this die-back leaves our industry with the predicament we are now in i.e. our per acre production is a fraction of the per acre production in other fruit growing areas – Washington State for example.
My point during the presentation was that compost application would eliminate the need for phosphorus stimulation in spring and in many cases also eliminate the need to follow-up with corrective chemical treatments to control the pathogens that attack the new roots.
Other fertilizer needs would remain the same or possibly lessen where a more vigorous feeder root system is maintained. Speculation has it that the compost is not supplying significant nutrition to the tree through the roots but rather modifying the soil microbial population and suppressing attack of the roots by the pathogens.
Research on compost impact on tree growth has been done over the years at PARC but up until just recently there was no sustainable supply of “tested” compost available to growers. My experience has been that many products growers have been using as soil amendments and generally labelled as compost have not been effective and in some cases were very detrimental to tree growth. The need for a standardization of the compost growers buy and assistance in proper application will be very important in future.