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 has had a major growth during contemporary times, one third of the world's population still relies upon traditional, small-scale farming practices. Though a declining population in the rural 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 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.
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 external 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.
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.
For agroecologists, weeds can actually be a way that helps decrease inputs while still growing healthy crops. Agroecology’s understanding of the role of weeds is that they help regulate nutrient cycling and protect soils from exposure to direct sunlight. Weeds retain some of the nutrients that crops that have been planted cannot absorb. When weeds die or dry out, the nutrients in their biomass are broken down providing nutrients for long-cycle crops and help maintain soil quality for short-cycle crops. The death and regeneration of roots help maintain the structure of soils, allowing easy entry of water and oxygen. What to be sure to avoid with weeds is the competition for the sun and preventing any unnecessary shade.
Soil Recovery 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 on hillsides, terracing, and riparian buffers.
Check out this video about using reduced-tillage systems for organic production.
Tillage is the agricultural preparation of soil by various mechanical or non-mechanical methods, such as shallow stirring or deep plowing and raking of fragmented soil particles. 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 helps manage 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, preventing the nutrients from leaching to deeper soil substrates. 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 rainwater 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 regulate the quantity of 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 biological 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 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 organic material such as dead plant or animal material, best if composted first, 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, sanitation and industrial purposes, a water management program is required to meet different needs in a balanced way and to avoid potential conflicts over disproportionate use and pollution.
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 the formation of mineral deposits and salinization in the superficial zone of soil. 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 seeping drips at an appropriate depth through a network of valves, hoses, 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: polycultures. More diversified plantings and intercropping can help maintain soil fertility, because different plants use different amounts of micro and macronutrients from the soil.
Perennial crops are particularly useful if they can be planted with annual crops. Perennial plants are alive year-round and can be harvested multiple times before completing its life cycle. When perennial plants are harvested, the soil fertility is left undisturbed. This increases the nutrients available to intercropped annual plants (Figure 30).
Balance and Management of Microorganism, Insect, and Pollinator Populations
Crop diversity reduces the likelihood of disturbing the balance of microorganism and insect ecosystems so as to not cause significant damage of the planted crops from these populations. Plant diversity also invites a greater variety of insects, some of which are natural enemies to plant pests and others that are helpful pollinators. Crop diversity reduces the likelihood that one insect can destroy an entire crop. These insects and other arthropods are critically important to agricultural ecosystems.
In addition to intercropping with plant species that attract insects that can do damage to the crop, trap plots can be planted. Trap plots are areas of mixed crop species planting placed near crops that attract predatory insects. Trap plots lure harmful insects into areas with more predators in order to prevent their spread to larger crop plantings. For example, corn or yellow flowering crops such as marigold or sunflowers attract insects. These can be planted on the borders of plot areas as trap plants to protect the crops.
To promote quality 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 approaches, we could significantly improve food and care for 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 can be studied and adapted 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?