Farm Forestry For Ex-Cane Land

by John Meadows 
This is an article previously published in the Spring 2005 edition of Southern Queensland Forestry News. In our latest edition published March 2007, we revisit this site for an update.
Throughout the Sunshine Coast region the sugar cane industry has been on a steady decline for the past number of years. With the rapidly developing population of the region, there is an increasing demand for land to accommodate new residential housing developments. However, there is also a strong voice of opposition being raised against this proposal, to preserve these wide green open spaces of agricultural land and contain urban sprawl.  Certainly some of this ex-cane land will be required to accommodate the growing population, and this appears to have been recognized in the recently released South-East QLD Regional Plan. The plan is proposing to allow housing developments on cane-lands to the east of the Sunshine Motorway, potentially providing these fortunate landowners with a financially rewarding ‘get-out’ option. But what about the rest of this land? What viable agricultural pursuits are available for these low-lying, often flood prone lands? A number of options are being considered by farmers including ‘cane candy’, soy, turf, sorghum, bamboo and farm forestry using native Australian hardwoods.  This case study presents an example of one affected landowner who has opted for the latter – a mixed Eucalypt farm forestry investment. After much investigation, the landowner engaged the Noosa Landcare Farm Forestry Program to undertake the establishment and early management of the plantation. An on-site interview between, and subsequent discussions with, NLFFP Manager Gary Clarke and PFSQ’s Executive Officer Ken Matthews provides the following details of the proposal.   The Site: This ex-cane growing property is owned by Mr. Matt Perry and family and is located along Paynters Creek Road, Rosemount, in the Maroochy Shire. The plantation site is just over 14ha and is generally all low-lying country, except for ~1ha along the northern boundary. The block slopes down to the riparian zone of the permanently flowing Paynters Creek, which forms the southern boundary. The soil consists of about 2.5m of loamy topsoil, over a sand base, with the top layer having formed a poorly draining cultivated crust. Existing drainage infrastructure included a main drain running through the centre of the block, and several minor drains zigzagging across the block to direct water flow back into this major drain. There is also an existing sub-surface drainage system (piping) in place, which is fairly common on low-lying cane growing land. Up until 2004, the entire block had been cultivated to produce sugar cane. Prior to works commencing the block was covered in cane stubble and regrowth up to 2m high in places, with the site estimated to be carrying 25t/ha of cane.       Site Preparation: Cane removal has involved a 3-pass operation – the site was slashed and left for 3 weeks before being rotary hoeing to integrate the cane mulch into the soil. To allow this mulch to break down, the site was then left for a further 4 weeks, before being disced. A D7H dozer with attached Savanna Rip Mounder was then used to deep rip and mound the site in preparation for planting. Planting rows have been high mounded via a double pass mounding operation. With the land-use history involving regular rotary hoeing over many years, and these recent works, there had been some concern about the possibility of overworking the soil, particularly in the top layer. The deep ripping has fractured the soil below the previous cultivation line and brought that uncultivated material to the surface and into the mounder’s path. It is believed that there will be enough vegetative material in the mix to rebuild soil structure, provided the mounds are well drained. The deep ripping works are about 5cm off the existing drainage piping, so it is expected that this will remain effective. Ensuring efficient drainage of the site has been a major priority of these earthworks. To facilitate this, the previously machine worked main drainage system across the middle of the property has been re-worked. The drainage was redirected to the natural line of the original drain, repairing the slumped areas and clearing the buildup of silt from its base. Silt and topsoil from these works has been used to build up the drainage batter banks and mounds.  Drainage slits linking to the main drain have been installed at ~12m intervals within the mounds.  Vegetative material has also been incorporated into this mix to help aerate and improve soil structure.

 The drainage banks will be planted out with a closely spaced (1 - 1.5m) rainforest species mix (based on locally occurring species), and all drainage slits are to be planted with Lomandra spp. There is also ~12m area around the drainage banks that has a hard pan and has never been worked, and so will be maintained as a solid grass mat. These measures are designed to reduce future erosion potential, effectively acting as filter zones so that none of the water coming off the plantation area will be able to enter the drainage slits or drainage line without passing through a vegetated zone.                                                                          

Plantation Establishment: Planting is anticipated to commence around September – October, provided the soil moisture content is sufficient to ensure early survival. The mounds will be mulched to retain moisture and this is expected to also assist with reducing weeds and their competitive effects around the tree bases. This spring planting would also help the trees to become well established and reduce the chances of frost damage during the following winter, although local farmers report that there has not been a bad frost in the immediate area in over 10 years. Access, form and lift pruning is expected to assist with promoting height growth to a single leader, sufficient to withstand potentially damaging frosts.  

Initial stocking is planned to be 1000 stems/ha, with rows at 4m intervals and 2.5m spacing between trees. As there is a level of uncertainty and risk relating to species performance on these flood plain sites, a mixture of suitable species has been chosen. These will include Eucalyptus grandis (Rose gum/Flooded gum), E. robusta (Swamp mahogany), E. resinifera (Red mahogany), E. pilularis (Blackbutt), E. cloeziana (Gympie messmate), E. microcorys (Tallowwood), E. pellita (Large fruited red mahogany), E. propinqua (Grey gum) and Corymbia variegata (Spotted gum). Approximately 50 – 70% of the planting will be the durability class 1 species E. cloeziana, to provide for early pole and round timber markets, and if the site remains flood free for the first 3-4 years, then this species will make up the bulk of the final crop. However, the species mixture will effectively back this up so that if overly wet years lead to poor performance of the more valuable and durable species, the structure of the forest can be maintained. Only very low numbers of E. pilularis will be used due to the experience in the area of this species suffering from windthrow on mounds.  

Future Management: As part of the establishment contract, NLFFP also handles the early maintenance, and in this case of an absentee landowner, will also likely handle the maintenance over the most intensive period of the first 5-6 years. Weed control will be limited to the use of Glyphosate, as the site’s drainage issues and proximity to the adjacent Paynters Creek will preclude the use of pre-emergent, residual herbicides.  Access, form and lift pruning will be essential on-going management tools during the early years of tree growth. Timing of non-commercial and commercial thinning is uncertain at this stage, dependent upon tree performance and effects of competition. In terms of nutrients, the superphosphate that has been poured onto the site in in the past hasn’t been processed due to aeration problems, and it is expected that it will now be freed up. Also, with the site’s shallow water table, it is expected that there will be plenty of available resources so as to reduce early competition between trees, thereby delaying a non-commercial thin until at least after 2 years. An important aim of this is to keep a high amount of pump action happening to lower that water out of the top profile as much as is possible. From experience on sites of a similar soil profile, where there is potential for pooling of water after significant rain, it has been observed that when the plantation reaches 1.5-2 years old,  there is significant movement of that water in the first week of pooling. Some sites are being drained away in 2 – 3 days, whilst adjacent areas are still saturated, so it appears the trees have a huge capacity to suck water, particularly if there is good survival right from the beginning and the site is kept at a high stocking level in the early stages.

The landholder is entering this farm forestry venture as a commercial investment, with long-term objectives of paying off the investment at around year 12, and with an anticipation of generating more significant returns in the 25 – 35 year range. It is believed the site is capable of delivering quality logs of up to 45cm DBH at around 25 years or trees will be retained until maximum value has been achieved.

To date the site is one of the larger ex-cane properties within Maroochy Shire to be planted under this type of farm forestry (~13ha), and it has attracted the interest of some adjacent landholders who may be looking for future viable land-use options. NLFFP manager Gary Clarke is cautiously optimistic and states ‘this is our first on cane land, although we’ve certainly done some stuff on wallum country before, but we just want to make sure our drainage systems are working out right in terms of costs and site conditioning’. Time will tell if the site works are effective, both in terms of drainage efficiency and costs, and if the site can deliver the expected growth and products. It is certainly off to a well planned and implemented start under the direction of this experienced and highly regarded farm forestry development contractor.   

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