Energy efficiency in Farming
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Prof. Leon Hugo
University of Pretoria
and
Jean Hugo
Tshwane University of Technology
The classification of agronomy systems according to productivity – searching for sustainability
Energy use analysis in production agriculture is essential for development of more efficient production systems. Energy is either directly or indirectly consumed in different operations of agricultural production, including cultivation, harvest and post-harvest logistics. At present the cost of energy is one of the greatest problems in the large-scale farming agro-ecosystem and all crops do not produce the same useful yields per unit of energy input.
Photo: Low-energy production systems
Photo: Medium-energy production systems
Photo: High-energy production systems
Agro-ecosystems can be classified in terms of energy inputs. The so-called low-energy production systems are mainly controlled by solar energy with a minimum of human input. Slash-and-burn and hunting activities of primitive cultures fall under this classification. Medium-energy production systems are those where solar energy is supplemented by wind, water, and animal power for irrigation, ploughing, etc. Subsistence farming is an example of this. In high-energy systems (also referred to as agri-voltaic) production is greatly increased by artificial inputs such as electricity, fuel, fertilizer, and pesticides. The mechanized farming systems of the First World produce large crop surpluses but not without great pressure on resources. In the graph to the right the relative efficiency of agricultural types is illustrated.
It is therefore important to find the ratio between energy requirements and the production of every crop. The gross energy requirement (GER) can be determined by reducing all the energy inputs to a standard value and then adding them together.
Graph: Effectiveness of agricultural types
(This calculation includes production, processing, packaging, marketing, etc.)
If the energy output (or production of food) per hectare is divided by the GER, the energy ratio (ER) of a crop can be calculated, for example: (See formula to your left).
A calculation can be made for each farming type. The smaller the ER the less effective the specific agricultural practice will be.
According to Tivy and O’Hare (1981) the ER value of pre-industrial crops could be calculated at > 10; crop farming is ten times less productive at a value of 1; whilst animal rearing is the most inefficient at 0.1. By comparison modern industrial forms of food production (ER 0,5-5,0) are less energy effective than semi-industrial forms (ER 2-10) and this is especially so when compared to subsistence farming systems (ER 10-70).
To obtain maximum yields, competing plants must be removed while the damage caused by insects, birds and wild animals must be kept to an absolute minimum. People form the second and third trophic levels, depending on whether the yield is directly used as in the case of wheat, or first fed to animals and the meat and other products then later consumed. The food chains are therefore to be short, while energy loss limited to the minimum. A large percentage of the biomass is of necessity lost as waste material as people only use certain parts of the plant. The rest is burnt or worked into the soil. If the yield is fed to livestock, a large amount of primary production is lost between trophic levels. From all wheat produced in the USA, only 10 percent is used for human nutrition. One third goes for fuel and same for feeding animals – losing a massive amount of energy for a hungry world. There are however extensive grazing areas of the world that cannot be used for the successful production of crops such as maize, beans, rice, etc. These areas can be used for livestock farming and their products used by humans. The yields from areas where crop farming is possible must rather be directly used by people and only supplemented by products from the extensive grazing areas. In this way the food requirements for the present world population can be met with greater ease.
Photo: Some extensive grazing areas could rather be used for the successful production of crops.
Despite scientific and technological agricultural developments of the past, such as the Green revolution, (see Agricultural Revolutions) which brought about the widespread adoption of agrochemicals and cross-breeding of plants, GMO’s, cloning, CRISPR gene editing, etc.) The values in the Table (below left) show the energy required for producing enough food for the world’s population, is becoming increasingly inefficient.
Table: Energy required by farming type
The following deductions concerning modern-day farming can be made:
- Mechanization is not energy effective.
- Crop production is more effective than rearing of meat or fish.
- Free grazing beef requires 0.5kCal energy input for every kCal produced which is much more productive than grass-fed beef which needs 6 times more input to produce.
The amount of energy lost between trophic levels is referred to as “Ecological Efficiency”.
Photo: Genetically modified crops displaces niche crops of the region
Photo: The use of pesticides reduces soil fertility
With a global population at 8 billion and expected to reach 9 billion soon, the massive production of food is a given priority. However, if this production process is inefficient and at the cost of the productivity of Nature, a crisis is unavoidable. Should extra energy become available for making food production more efficient, what is the negative ecological side-effect of it? Modern farming has led to significant soil degradation due to excessive tillage by ultra-heavy machinery, compacting the topsoil. Monocropping has reduced soil fertility and intensive agriculture has contributed to loss of biodiversity. Expansion of agricultural land leads to clearance of large tracts of indigenous vegetation, contributing to loss of habitats and global warming.
Photo: Ecological devastation of productive mono-crop farming
Dependence on chemical inputs has also led to the development of pesticide-resistant pests and negatively impacted human health through exposure to harmful chemicals. The heavy use of synthetic fertilizers and pesticides has polluted waterways and harmed aquatic ecosystems. Increased greenhouse gas emissions have led to air pollution and the exacerbation of climate change. As result of these and other negative impacts, soil loses natural fertility. Poorer production leads to more fertilizers needed. To continue to ensure food security, the potential of the soil must be artificially boosted – a downward feedback system. This is presented in Wikipedia: The Environmental Impact of Agriculture.
Other socio-economic negative trends that follow on the heels of industrialized farming methods are the reduced need for labour due to mechanization, leading to loss of jobs and income, rural depopulation, and the decline of rural communities, disrupting social life. These factors collectively threaten long-term agricultural sustainability, social cohesion, and environmental health. Truly an unsustainable situation.
Photo: Strong bods between farmer and animals exist.
Photo: Proudly selling her family’s produce.
Photo: Family and community working together.
Should one accept that modern-day industrial farming is not sustainable, is there a way to transform it? Can we return to traditional ways and yet produce enough for a growing population? Traditional agriculture can be quite stable as in China where in certain areas production has been productive for 5000 years (Foreman & Godron, 1986. p 293). On the other hand, however, there are more examples where so-called “breadbaskets” (i.e., areas of high productivity) have collapsed under mismanagement. Zimbabwe being one close to home.
The so-called New Agricultural Revolution cycle incorporating the sustainable farming phase (where humans started to accept the necessity of veering away from insecticides, fertilizers, genetically modified organisms, etc. to natural ways of organic food production), developed over the past decades. (See examples of such enterprises in “5 Most Epic Earth Healing Projects!” in the video to your left. The terminology used for these initiatives varies.
Terms to describe them include conservation farming, permaculture, organic farming, integrated organic farming, regenerative farming, sustainable farming, holistic farming, deep bed farming, and more.
The definition of each differs but all of them have the following in mind: it is environmentally non-degrading, technically appropriate, economically viable, and socially acceptable. In the light of the elusiveness of the concept of sustainable farming, one can only hope that the rediscovery of traditional ways can be merged with modern technology to bring about food security for a fast-growing world population.