July 2007: Soil Oxygen Trial Shows Promise
The Wormtech Report No. 11      

A recent trial of a new product which injects concentrated oxygen deep into the topsoil shows good promise for the kiwifruit industry.

The new product, Wormtech Extra, is produced by Bay of Plenty soil health company Wormtech NZ Ltd.  It combines liquid vermicast, humic acid, and oxygen source UNLO2K and is now available to growers nationwide directly from Wormtech.  It is usually injected into the soil by the unique Gwazae Ground Probe Aerator, developed and manufactured in Tauranga and also available through Wormtech.

“To see improvements in all four measures of fruit development - dry matter, TZG, black seeds and brix – was very encouraging” says Greg Walker, managing director of Wormtech.  “We have always been interested in helping growers achieve earlier fruit maturity as well as bigger crops, and have had success with spraying and injecting Wormtech Ground and other products in the past.” 

The trial was conducted on a kiwifruit orchard near Edgecumbe, and compared two strengths of Wormtech Extra with a control block treated with Wormtech Ground.  Wormtech Ground is an established product which comprises the same vermicast and humic acid, but not the oxygen booster.  Each block was treated once only in December 2007 with 100 litres/hectare using the aerator machine.  Samples of fruit from the three blocks were then tested in March for fruit development. 

As this was not a large trial and sample sizes were limited, the results should be treated with caution, but they are as follows:

“Recently we have been looking at the crucial role of oxygen, both for the soil population of aerobic bacteria which convert applied nutrients to plant-available form, and for the development of the fine feeding root hairs themselves.  Intensively cultivated soils often suffer from not only compaction, with the associated problems of poor nutrient and water mobility, but also low worm and microbe populations. 

“To see this much apparent improvement with our newest product is just great.  Not only are there financial incentives from Zespri for making early harvests, but there is also the avoidance of anxiety due to the risk of early winter frosts hitting the crop before it is ripe.”

“We were working on getting the formulation of the new product right, and we used 5% and 10% UNLO2K.  The new additive is not cheap and we did not want to use a higher rate unless there was a demonstrable benefit.  It seems that there is, particularly in brix in this trial, and we have settled on 10% UNLO2K in Wormtech Extra. 

“With the launch of this new product we can now in one simple unobtrusive process, decompact the soil, while at the same time adding beneficial bacteria and fungi, nutrients, water-retaining humic acid, and now concentrated oxygen” concluded Greg.  “Whilst trials will continue, we expect to see applications across a wide range of crops.”