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Trees on farms

DATE 13/12/2010

MY PERSPECTIVE OF TREES–ON–FARMS
By Evan D. Shield


Introduction

It is no longer alarmist to be concerned about the inexorable global trends of population growth, land degradation and deforestation, food and energy insecurity and global warming / climate change. These are issues currently demanding but, regrettably, not yet receiving, urgent international action.

The warnings of Prof. John Beddington (Chief Scientific Adviser to the U.K. Government) that a “perfect storm” of food shortages, scarce water and insufficient energy resources could occur by 2030 are not the only signals of the need for urgency. He indicated that “by 2030, we need to be producing 50 % more food. At the same time, we will need 50% more energy and 30% more water”. These estimates should be read in terms of the availability of the resources necessary for production. In this context, Prof. Rattan Lal (Ohio State University) has indicated that the severity of global land degradation is such as to require, by 2050, each person in the projected global population of 9 billion to be dependent on an average of just 400 square metres of land for all their food, feed, fibre and fuel requirements.

Thus, the urgent global need is not simply for greater levels of production, but also for greater productivity in terms of use of the resources required for that production, for production with lower environmental impacts and for rapid rehabilitation of degraded lands.

Trees-on-Farms

In this context, a Trees-on-Farms strategy seems to have a role to play. Rowan Reid (Australian Master Tree-Growers programme : ref. www.agroforestry.net.au has indicated these benefits to farmers who diversify by planting trees on their properties :

• shade and shelter for livestock ;
• windbreaks for pasture and crops ;
• soil conservation and salinity control ;
• biodiversity and aesthetics ;
• carbon sequestration ; and,
• commercial tree products (timber, fuel, fencing materials, fodder, essential oils and food (honey).

My approach acknowledges these benefits, but has strong focus on how they are delivered. Two matters seem essential to stimulating the highest level of farmer interest in a Trees-on-Farms strategy. I believe :

• the tree crop needs to be carefully integrated with the farmer’s traditional land-use ; and,
• the farmer must be offered the opportunity to produce commercial tree products of highest value.

Without these policies, there is a risk that trees will be block-planted, fence-to-fence in a back paddock little valued by the farmer because of its poor productivity (due to soil quality, stoniness, poor drainage, steep slopes, weed infestation etc.). In such a situation, not only is productivity diminished, but interest in protection and silvicultural management interventions is likely to be minimal and / or poorly rewarded.

The outstanding benefit of careful integration of the tree crop with the farmer’s traditional land-use is that the traditional land-use derives direct benefit from the trees. The good example of this is found in research indications that up to 10 % of pasture land can be planted to trees without loss in livestock weight-gain productivity. This is testament to the benefits of shade and shelter provided by trees to livestock. Another example is of the improved pasture and crop productivity resulting from the capacity of planted trees to lower the water-table and thus reduce damage by saline soil conditions.

While these benefits may be significant, it is probable that most farmers will require stronger incentives before they become fully enthusiastic about Trees-on-Farms.

Thus, wherever possible, Trees-on-Farms projects focused on production of high-value roundwood are preferred. Such roundwood will be used for poles and piles, for sawing into timber and for rotary peeling into veneers. The fact that production of high-value roundwood demands silvicultural interventions – particularly thinning and pruning – is entirely consistent with the need for careful integration with the farmer’s traditional land-use. For example, a Eucalypt plantation intended for high-value roundwood production will require thinning for maintenance of a low stand density, a condition entirely consistent with growing grass or improved pasture under the trees, as shall be demonstrated.

An additional potential benefit to farmers participating in a Trees-on-Farms project – and one that may not now be far from reality – is self-sufficiency in energy through the processing of wood and crop residues. Electrical energy via pyrolysis or gasification is likely to be the first form available, with bio-diesel a subsequent development.


Outstanding Examples of Trees-on-Farms

Not surprisingly when the pressures on its land resources are considered, India provides wonderful and diverse examples of success with agro-forestry Trees-on-Farms projects. Here is one example :
 

Figure 1. : A clonal plantation of E. tereticornis (aged 2 years) over a wheat co-crop in Punjab, India.
Figure 1. : A clonal plantation of E. tereticornis (aged 2 years) over a wheat co-crop in Punjab, India.

However, it seems probable that silvo-pastoral projects will be of greater significance in Tasmania. ABARE’s 2010 statistics indicate that of the state’s 3,583 farms, 1,697 (47%) are bovine-based (for beef or milk production). This number excludes 276 farms producing a combination of sheep and beef, 473 specialized sheep properties and 163 grain-and-livestock farms. Thus, the following example of excellence may be more relevant.

Near Montecarlo in Misiones Province, Argentina, Australian tree seed, Australian pasture seed and Australian Braford and Brangus sperm are combined with Argentine design and management to produce a silvo-pastoral project which may be an examplar for the world. The 2,000 hectare property is known as La Pera and is owned by Trumpp Hnos..

Currently, there are 1,300 ha. of hybrid pine and 700 ha. of Eucalyptus grandis, both with improved pasture, typically Bracharia brizantha cult. marandú. Progressively, the Eucalypt area will be increased at the expense of that of pine because of higher productivity and better market acceptance.
 

Figure 2. : La Pera, Misiones, AR : 450 stems per ha. of hybrid pine at 12 years of age over improved pasture.
Figure 2. : La Pera, Misiones, AR : 450 stems per ha. of hybrid pine at 12 years of age over improved pasture.
Figure 3. La Pera, Misiones, AR : 200 stems of ha. of E. grandis at 5 years over improved pasture.
Figure 3. La Pera, Misiones, AR : 200 stems of ha. of E. grandis at 5 years over improved pasture.

In neighbouring properties where “open-sky” grazing is dependent on native pastures, a typical beef production increment is stated to be 100 kg. live-weight per ha. per an.. With “open-sky” grazing of improved pastures, productivity can be lifted to 231 kg. live-weight per ha. per an. at a stocking rate of 1.64 head per ha.. However, the grazing on the same improved pasture type under trees produces an average of 450 kg. live-weight per ha. per an. at stocking rates varying from 1.5–2 per ha. for cows to 4 per ha. for weaners (of 140–150 kg.). And as for tree productivity, I measured a 12 year-old E. grandis tree at 54cm. breast-height diameter in one field.

Conclusion

Under a Trees-on-Farms strategy, the synergies between well-managed tree plantations, improved pastures and intensive rotational live-stock grazing offer opportunities for significant improvements in farm revenues and profitability. This combination also provides off-sets to methane emissions, enhances productivity of traditional farming and can contribute to residue-based bio-fuel production.

Figure 4. : Dinninup, W. A. (MAP = 550mm.) : A silvo-pastoral project with E. saligna at 17 years over native pasture
Figure 4. : Dinninup, W. A. (MAP = 550mm.) : A silvo-pastoral project with E. saligna at 17 years over native pasture