I recieved the following note from Aaron Edmonds, 2002 Nuffield Scholar and Farmer:
“Agriculture has evolved to the assumption that oil and gas will always be cheap. Large amounts of energy are used in food production making agriculture the third largest energy consuming sector globally. Most people would be aware of the diesel fuel requirement to power the machinery used in crop production. What they would not be aware of is that diesel use is only a small component of the total energy demand in this process. In fact it is in the manufacture of fertilizers used to fuel crop growth where the largest energy liability occurs. To put it into perspective, it takes the energy from roughly one litre of oil to produce one kilogram of urea, the most widely used nitrogen fertilizer. Not to mention the petrochemicals and energy required for herbicide and pesticide manufacture. Agriculture will continue to incur fertilizer, pesticide and fuel cost increases proportional to rises in oil and gas prices. Quite clearly as energy concerns begin to emerge, agriculture must reduce its dependency on energy.
There are three areas in which total energy demand can be significantly reduced in Australian broadacre agriculture and not surprisingly these also bring sustainability gains almost as an added bonus. Sustainability it seems in the true sense of the word, simply means turning agriculture from a net energy user to a significant net energy producer!
Firstly it is highly desirable that crops be perennial in their growth habit. This means they survive from one year to the next and only need planting once. This saves on the need for heavy agricultural equipment and the diesel currently needed to sow common staple food crops like wheat, rice and corn on a yearly basis. The environmental gains from a perennial plant are a large root system preventing soil erosion, enabling use of subsoil moisture to prevent salinity and allowing deep access to leached fertilizers and nutrients. Perennial plants are also far more competitive with weeds.
Secondly there must be a legume base to the crop production system. Legumes are plants that enable nitrogen to be biologically fixed around their root systems and hence have no need for man made fertilizers to satisfy nutrition. Some common legumes include soybeans, peas, beans, chickpeas and lentils. The energy savings in legume based systems from requiring no nitrogen fertilizer are enormous. All natural plant ecosystems have a legume base within them which are the drivers of fertility.
Thirdly, in conventional agriculture, herbicides, fungicides and pesticides are required to control pests and diseases. These are produced with complex and energy expensive industrial processes quite often using petrochemical precursors. As our crops have been bred to focus almost completely on yield and not on traits that allow them to tolerate and compete with pests and weeds, man has insured productivity is linked to the high use of chemical inputs. This effectively means that the energy required for pest and disease control in the plant is ultimately sourced from fossil fuels. Whereas wild plants and wild relatives of our commercialized crops have developed unique means to survive pests and compete with other species.
Ironically it is a native plant that has not been exposed to modern man’s short sighted breeding efforts that offers Australian farmers the ability to greatly reduce energy dependency in food production. Australian sandalwood (Santalum spicatum) is a unique native tree crop highly adapted to Australia’s harsh conditions. The tree produces nuts that are high in oil (60%) and protein (18%) with the kernel oil being largely monounsaturated (55%) – the healthiest of oils. It requires no nitrogen fertilizer inputs as it is hemi-parasitic. It hosts on the root systems of native legumes such as Acacia’s sourcing nitrogen needs that are biologically fixed. The sandalwood nut will be an important oilseed crop in the future.
Trials for this dryland tree crop are underway at Aaron Edmonds’ farming property east of Calingiri in the Western Australian Wheatbelt. He has been making selections from local trees for large seededness and has varieties whose nuts are as large as a 20c piece. Four year old trees in his plantings are yielding well in excess of 1kg per tree, with this yield set to increase as the trees grow bigger. A planting density of 600 trees per hectare in a 350mm rainfall zone, could lead to a yield on a per hectare basis of around 600kg. The major energy cost in this system being weed control and harvesting, still significantly well below that of wheat production.
Plantings will continue on the Edmonds property who are quite probably becoming the world’s first broadacre producers to achieve significant energy efficiencies in food production. 50 hectares are earmarked for 2006 on top of the 30 hectares already established. Poorer soil types such as sands over gravel and areas prone to frost are being targeted first. These are the areas where energy investments in the form of fertilizer and herbicides are generally the highest risk.
Such oilseed crops as the sandalwood are essential to the future farm landscape, allowing farmers to profit rather than pain from the energy market and also to achieve energy self sufficiency in food production. Aaron’s vision is to see significantly more plantings of this amazing production system throughout the Wheatbelt.”