LONGSTEM NATIVE tubestock, originally developed as an alternative to willows in riparian environments, is opening up a promising option for planting directly into salt-affected areas.
There has been significant loss of conventional tubestock in salinity revegetation projects, generally due to the hot salt crust destroying the shallow-planted root structure of standard tubestock plants.
According to Bill Hicks, the man who developed the longstem technique, the use of deep-planted longstem tubestock removes the root ball from the hostile, crusty surface environment and places the roots in a cooler, sometimes moist, situation 60-90 cm below the surface.
About 10 years ago, Mr Hicks, a retired Hunter Valley electrical engineer and lifelong environmentalist, decided to research the possibility of replicating in native species the characteristics of willows that made them such a popular choice alongside Australian waterways.
Willows can be deep-planted as a hardwood cutting and are capable of fast growth. They gain a strong resistance to wash away in flood conditions as a result of the deep planting. Until Mr Hicks came along, native species were not suited to deep planting as hardwood cuttings.
However, recent willow imports have introduced seed reproduction into the picture, threatening a massive willow weed problem alongside many rivers and streams, and creating an urgent need for an alternative.
The longstem tubestock system of growing and planting natives replicates entirely the willow's positive characteristics as cuttings, according to Mr Hicks who explained the system to Ground Cover.
Trees and understorey shrubs are grown in standard 50 mm forestry tubes to a height of about 1 metre and matured in the tubes for a period of about 15 months before planting. During this time they are subjected to a specific nutrient and storage regime. The trees are then planted with the major part of the plant submerged below the soil surface.
In achieving these results, Mr Hicks says he overturned two long-held horticultural principles. Firstly, that the plant stem must never be submerged more deeply than the soil surface level of the container for fear of stem fungal diseases. Secondly, that large plants could not be grown in small containers without causing permanent damage to the root system and thus inhibiting future healthy growth.
"In fact, longstem plants, deeply planted, not only survived, but progressed far more satisfactorily than conventional surface-planted tubestock.
"The ability to achieve a healthy plant grown to about 1 metre in length in a container of very limited size without root damage was achieved through the development of a special fertiliser regime which enabled the plant to reach this substantial size without the need for significant root development. "
There are now close to 200, 000 longstem native tubestock plants growing across Australia in riparian revegetation programs with outstanding survival rates, far outstripping standard tubestock.
Applying longstems to salinity management
"It (then) became obvious that this same deep-planting technique could have benefit in overcoming problems being experienced in revegetation programs in areas of high salinity.
"The feeling was that deep planting would place the root ball in a more benign soil structure below the salt crust, with minimum damage to the plant in its early growing period. It must be emphasised that the trees and shrubs being planted must be salt-tolerant species capable of sustaining growth in the saline soil conditions.
Following some encouraging trials, a dryland salinity-affected area in the Upper Hunter Valley was planted progressively with 2, 500 salt-tolerant trees in late 2001. "The survival success and growth rates have both been outstanding and seem to confirm that this will be a major application of plants grown and planted employing the longstem tubestock system.
"These trees have not only survived a period of record drought and above-average maximum temperatures, but also frosts that were' the worst in living memory. This is, of course, in addition to surviving the saline environment on their sensitive young root system. "
Species included in initial trials and in the Upper Hunter project include Eucalyptus robusta, E. camaldulensis (three salt-tolerant provenances), E. botrioides, E. tereticornis; Melaleuca styphelioides, M. liliariifolia, M. quinquinerva, M. bracteata, M. nodosa; Acacia binerva, A. saligna; Casuarina glauca, C. cunninghamiana (seed collected from saline tidal margins).
These species were selected to prove the effectiveness of longstem tubestock for salinity control and were not especially chosen to preserve site biodiversity. The selection of species for saline revegetation would depend upon the local situation and available tree and understorey varieties that were known to have salt tolerance.
HOW IT'S DONE
LONGSTEM TUBESTOCK is planted using water-jetting techniques, originally employed to insert willow cuttings, or with the aid of a petrol-driven auger to develop the planting hole.
Bill Hicks and his company, Norkhil Technologies Pty Ltd, have conducted numerous workshops to encourage the use of the longstem plants and to advise community and commercial nurseries how to grow them. These workshops are ongoing and many nurseries now offer longstem native tubestock grown to Mr Hicks' formula. Substantial National Heritage Trust funds are supporting the use of these plants in tree planting activities.
The formulation for the fertiliser regime is available free on application by phone or email from Norkhil Technologies Pty Ltd. The full procedures applying to the longstem system including theory, planting methods, nursery techniques and field results are available on video both on VHS cassette and DVD. These are also available from Norkhil.
Contact: Mr Bill Hicks, Norkhil Technologies Pty Ltd 02 4998 8387; fax 02 4998 8364 email firstname.lastname@example.org