Some experts believe that Europe is furthest ahead in developing nation-wide plans for sustainable agriculture in the 21st century. You will read about this in the upcoming Action Section.
The heavy equipment, irrigation technologies, chemical fertilizers and pesticides, and genetic modification of crops and livestock characteristic of Industrial agriculture have increased agricultural yield and the conventional calculation of economic efficiency. Yet, as we have noted, these benefits have come with environmental and human health costs.
At the beginning of this Science section, we noted that even though the industrial food system is a major feature of the contemporary world, one third of the world's population still relies upon traditional, small-scale farming practices. Though a declining population on the world stage, many traditional farmers and fishermen possess intimate knowledge of the natural world that is important for the future of life on Earth. In many ways, sustainable food systems are attempts to join the wisdom of people working inside traditional food systems with new knowledge from environmental science and technology in order to create a food system that is ecologically sound. Here, we will only touch upon five techniques characteristic of sustainable food education and practice today.
It will take courage to transition from an industrial food system to a sustainable food system. In the upcoming Ethics Section there is a discussion about how the moral virtue of courage relates to food.
There are many programs around the world today dedicated to recovering and promoting the wisdom of traditional agriculture for the next generation of farmers. One successful example is the organic agriculture program at the Sekolah Dasar Pangudi Luhur Kalirejo Primary School in the Yogyakarta District of Indonesia. Watch this short video on the school program.
Practitioners of sustainable agriculture seek ways to reduce the amount of external inputs needed to maintain long-term crop production and food distribution. This is because minimizing the inputs (fertilizers, pesticides, water, energy) decreases many of the negative environmental impacts of industrial agriculture, such as nutrient run-off; toxicity in crops, soils and water run-off; and production of greenhouse gases. Minimizing inputs is a central principle of sustainable agriculture practices with each annual planting and growing plan.
Soil Building and Maintenance
One of the most important components of soil management is erosion control and prevention. Methods commonly used to prevent erosion include: reduced tillage agriculture, cover cropping, contour planting, terracing, and riparian buffers.
Check out this video about using reduced-tillage systems for organic vegetation production.
Tillage is the agricultural preparation of soil by various mechanical or non-mechanical methods, such as digging, stirring, and overturning. Most tilling methods use a plow to turn a field’s soil over before planting. This can help control weeds, aerate soil, and break up compacted soil, allowing for better water penetration and absorption. In colder climates, plowing the soil kills many pest insects that normally overwinter in plant residues. However, plowing also exposes the soil to the erosive forces of wind and water. As we have noted above, this has led to a massive loss of fertile soils around the world.
An alternative to plowing is called reduced-till agriculture. This farming method leaves the soil structure intact, decreases compaction and allows a crop’s roots to persist in the soil after harvest. It also holds soil in place and allows for greater accumulation organic matter over time as plant roots are decomposed. Reduced-tillage is achieved by cutting small slits in the soil’s surface to plant each crop, so that the majority of the soil is left undisturbed. Soil erosion is usually reduced substantially by reduced-tillage agriculture.
A successful example of reduced-tillage techniques is one that has been employed in the Indian states of Haryana and Begusarai (Figure 25). In 2003, a comprehensive survey of farmers who ploughed their fields compared to those who minimized tillage showed that reduced-tillage methods helped rice and wheat farmers lower the cost and labor that went into preparing the fields for planting. Additionally, diesel fuel use was reduced by 60 liters/hectare. Because pre-seeding irrigation was unnecessary, water use decreased 20%. With the reduced-tillage method, planting could begin earlier. This allowed for a longer growing season that increased the average wheat yield by 8%.
Cover Cropping and Contour Planting
Planting cover crops on fields that are not actively growing food crops can help prevent soil exposure and improve soil health (Figure 26). Cover crops also help hold nutrients near the soil surface, keeping the nutrients from leaching out. When used as cover crops, legumes fix atmospheric nitrogen, greatly enhancing soil fertility.
Contour planting (Figure 27) is a method used to decrease erosion when crops are planted in hilly areas. By planting horizontal rows that follow the natural contours of the land, soil that might be carried downhill by rain water is intercepted and captured on the shelf of the adjacent downhill row. This practice is more effective when a mixture of crops is planted in strips, preferably with some strips being composed of grasses that act as filters that are very effective at trapping soil run-off.
Planting trees with grasses and other densely-growing vegetation near water edges produces riparian buffers which help capture soil and nutrients in runoff before they enter the stream and cause eutrophication (Figure 28). These features are also relevant to the preservation of biodiversity in agricultural landscapes because riparian habitats can support many plant species and act as corridors for animals and insects.
Organic Soil Additives
Many of the techniques used to decrease erosion also help increase soil organic matter, nutrient content, and overall fertility. Conversely, increases in soil organic matter can help soils adsorb more water and reduce erosion.
Read more about organic soil additives.
While it is ideal to minimize the amount of any inputs to a site, if the soil in an area has poor fertility to start with or has been degraded through intensive farming or industrial forming practices, it will need to be improved before it will be productive. In general, soil improvement can be accomplished by adding dead plant or animal material and allowing it to decompose. This increases the amount of carbon, nitrogen, phosphorus, and other macro and micronutrients at the site.
Efficient water usage and the control of water movement following rainfall is key to sustainable agriculture. Because water is also needed for drinking, cooking, sanitary, and industrial purposes, balancing water usage among these competing needs is critical to a good water management program.
Much cultivated land is currently in areas that do not have predictable annual rainfall. Due to global climate change, farmers in many parts of the world are finding their traditional expectations of rainfall frequency and intensity dramatically altered. As a result, irrigation from groundwater will probably be necessary for the near term. However, as discussed above, groundwater irrigation can lead to mineral deposits and salinization. These factors can be mediated by soil-based solutions, appropriate timing of water application, and the use of efficient modern irrigation technologies.
One of the most effective water conservation technologies is drip-line irrigation. This method delivers water to crops in slow, deep seeping drips through a network of valves, pipes, tubing, and emitters placed on the soil surface (Figure 29). Very little water is lost through evaporation in drip-line systems, as opposed to larger sprinkler systems.
The environmental problems associated with monoculture farming are addressed by the opposite: diverse crop farming. More diversified plantings and intercropping can help maintain soil fertility, because different crop species use different amounts of each micro and macronutrient.
Perennial crops are particularly useful if they can be planted with annual crops. Perennials plants are alive year-round and can be harvested multiple times before dying. When perennial plants are harvested, plant biomass in the soil is left undisturbed. This increases the nutrients available to intercropped annual plants (Figure 30).
Pest and Pollinator Management
Crop diversity reduces the likelihood that one pest can destroy an entire crop. Plant diversity also invites a greater variety of insects, some of which are natural enemies to plant pests and others that are helpful pollinators. These insects and other arthropods are critically important to agricultural ecosystems. Crop diversity reduces the likelihood that one pest can destroy an entire crop. Plant diversity also invites a greater variety of insects, some of which are natural enemies to plant pests and others that are helpful pollinators. These insects and other arthropods are critically important to agricultural ecosystems.
In addition to intercropping with plant species that attract insects that feed on pests, trap plots can be planted. Trap plots are areas of mixed crop species planting placed near crops that attract predatory insects. Trap plots lure pests into areas with more predators in order to prevent their spread to larger crop plantings.
For the sake of the food all abiotic creatures depend upon for life, it is wise for us to learn from 1) food data given in environmental science, 2) the wisdom inside traditional agricultural systems, and 3) the innovations of contemporary sustainable agriculture. By combining these three sources with environmentally sustainable technology, we could significantly improve food and its ultimate source: our Earth.
Nicholas Tete SJ, of St. Xavier’s University College in Jharkhand, India is a Healing Earth scholar and specialist in sustainable food systems. He has provided the following detailed studies of sustainable agriculture techniques. Though written in an Indian context, the basic ideas are transferable to any region of the world. To open the documents, click on the title.
As seen throughout this Food and Science section, the activities of food production, processing, distribution, consumption, and disposal raise serious ethical questions. We have already touched upon many of these in this section. We turn now to a more detailed discussion of these challenges in the Food and Ethics section.
Questions to Consider
- If you were to plant and maintain a garden where you live, what methods of sustainable agriculture from those discussed by Fr. Tete above would you try to use?
- If someone was admiring your garden, how would you explain the environmental and human health benefits of the sustainable methods you are using?