Breaking Bread - The Harvest
This is part one of the Breaking Bread Footprint Focus series.
Cereal grain* forms around 50% of bread mixture and is the material that consumes considerable natural resources to produce. Their versatility as crops and food ingredients has made these grass varieties the world's most widely produced plant. Cereals are cultivated on a massive scale using industrial agricultural processes to maximise crop yields grown on millions of hectares of land.
This article describes the grain production process and its material resource inputs, activities and potential environmental impacts. It finds that the conversion of natural land for intensive, chemical assisted agriculture contributes to human induced climate change, natural resource depletion and biodiversity loss.
*As a product in its own right, grain could be the subject of its own Footprint Focus but it is covered here in the bread lifecycle due to its major contribution to the bread product footprint.
Ingredients
The basic materials and equipment needed to produce a cereal grain crop can be loosely summarised as: land with fertile and hydrated soil; protective supplements, machinery and fuel. The specific forms and makeup of these materials affect the environmental footprint of the production process.
Intensive crop farming methods, known as monocropping, is based on the continuous application of chemical fertilisers chemical pesticides. Thus the materials can be expanded out to the list in Table 1.
Table 1 - list of raw materials used to produce cereal grains with roughly estimated quantities per hectare of land per crop year.
| Resource | Unit | Quantity per hectare | Total Occupied Land Area |
|---|---|---|---|
| Land | hectares | 1 | 220m |
| Grain | tonnes | 5 | 1.2 bn |
| Soil | m3 | 20,000 | 4.4tn |
| Water | m3 | 2000 | 440bn |
| Nutrients: | |||
| Nitrogen | kg | 13 | 2.8bn |
| Phosphorus | kg | 6 | 1.3bn |
| Potassium | kg | 9 | 2bn |
| Pesticides | kg | 5.2 | 1.1bn |
| Machinery fuel | litres | 30 | 6.6bn |
Directions for use
The main cereal crop farming are the conversion and cultivation of land, the hydration, nutrition, protection, harvesting and conditioning of crops.
Land conversion and cultivation
The starting point is the acquisition of land suitable for cultivation. Industrial farming requires large areas of suitable land to achieve economic viability. A standard wheat farm in the United States is 400 hectares or 4 square kilometres, which is the size of a small town.
To be suitable for cultivation, the land needs to be open, flat and contain adequate depth of fertile soil. Depending on its previous function, the land may need to be cleared and prepared for cultivation using chemical treatments and heavy farm machinery.
Crop hydration
Keeping the crops hydrated is essential for maintaining healthy crop growth, soil fertility and climate regulation. Industrial irrigation systems commonly provide a mixture of green water stored in soil and blue water sources extracted from large bodies of water such as lakes, rivers and aquifers.
Crop nutrition and protection
Alongside water, the supply of nutrients is vital for growing healthy crops. For bread cereals, nitrogen is the most important nutrient followed by phosphorus and potassium. Monocropping requires a continuous supply of these nutrients through organically or industrially produced fertilisers.
Manufactured fertilisers, which are the most widely used, are produced using fossil fuels before being packaged and transported to farms for application. Organic fertilisers are agricultural by-products - livestock manure or decomposed plant material.
Crops also need protecting from the potential damage caused by pests, weeds and disease. The primary agricultural method used to control these threats is the application of chemical treatments known as pesticides.
Crop harvesting and conditioning
Last but not least (yeast?) are the harvesting of the crop using combine harvester vehicles and the drying of the harvested grain so it can be stored and transported.
Footprint Notes
The environmental footprint of cereal grain production is considered in relation to the global growth of industrial agriculture that has severely depleted the planet's land supply and ecological services.
Industrial agriculture is dominated by the practice of monocropping where single crops are grown continuously and intensively on the same land in perpetuity. Designed to maximise crop yields, this approach depends on a range of techniques and supplements to provide the additional water, nutrients and protections monocrops require to maintain these yields over time. But while the end result is higher yielding crops, the practice of monocropping comes with a variety of environmental burdens.
To illustrate the scope and scale of grain production's footprint, the cultivation process is broken down into the main sources and summarised in Table 2.
Table 2 - environmental impacts of cereal grain cultivation on four categories of environmental condition.
| Means | Function | Climate change | Natural resource | Biodiversity | Air quality | |
|---|---|---|---|---|---|---|
| monocrops | maximise efficiency & yields | reduced carbon sequestion | land, soil, water depletion | loss of plant, insect, bird, mammal species | ||
| synthetic fertilisers | supplement and replace soil nutrients | nitrous oxide and carbon emissions (production & packaging) | land, soil, water degradation | exposure of organisms in soil and marine to harmful nitrates and eutrophication | release of ammonia, nitrous oxide | |
| pesticides | protect against pests, weeds and disease | emissions from (production and packaging) | exposure of soil organisms, insects, plants; birds, mammals to chemicals directly or in food chain | airborne spray drift | ||
| irrigation | supplement hydration | freshwater depletion | natural habitat loss from water scarcity | |||
| machinery | tillage of land, use of chemicals, harvesting and conditioning of crops | CO2 emissions from production and operation |
Global warming and climate change
Cereal monocrops release the greenhouse gas Nitrous Oxide, and to a lesser extent Carbon Dioxide, which has a short-term warming effect on the atmosphere.
The largescale conversion of land reduces nature's carbon sequestration capacity.
The manufacturing and operating of chemicals, machinery and buildings are sources of carbon emissions.
Natural resource depletion
Producing enough grain to satisfy global demand requires substantial occupation and conversion of land.[1] Land use change on a large scale degrades vital ecosystem services.[2]
Intensive farming consumes large volumes of freshwater which may contribute to water scarcity and imbalances.[3]
Biodiversity loss
The effects of land conversion and the practice of monocropping on biodiversity include the loss of natural habitats; and the degradation of soil composition, structure and organic content, all of which contributes to its capacity to renew, regulate and support itself and connected ecosystems.[4]
The widespread use of pesticides can contaminate soil and water sources causing potentially harmful effects on non-targeted plants and wildlife.[5]
Air quality
The fertilisation of crops releases ammonia, nitrous oxide and other gases, which combine with other air pollutants from transport and industry to create harmful particular matter.
In some parts of the world the practice of crop burning to clear residue is a periodic source of local air pollution.
Food for thought
The grain used to produce bread has a footprint consisting of land occupation, greenhouse gas emissions, soil degradation and the generation of water and air pollutants.
Intensive farming seems to be a double-edge sword for the environment as it reduces the land needed for a given quantity of grain but increases other environmental costs.
However, there is real potential to reduce the impact of intensive farming techniques while maintaining high yields. These include integrated Irrigation and Nitrogen Management[6] and developing sustainable farming policy frameworks[7]
Ritchie and Roser, ‘Half of the World’s Habitable Land Is Used for Agriculture’. ↩︎
Peng et al., ‘Land Conversion to Agriculture Induces Taxonomic Homogenization of Soil Microbial Communities Globally’. ↩︎
Abdelazez et al., ‘Impact Of Climate Change On Wheat Water Consumption In Some Egyptian Regions’. ↩︎
Rodríguez et al., ‘Costs and Benefits of Synthetic Nitrogen for Global Cereal Production in 2015 and in 2050 under Contrasting Scenarios’. ↩︎
Isenring, ‘Pesticides and the Loss of Biodiversity’, Pesticide Action Network Europe. ↩︎
Brunelle et al., ‘Reducing Chemical Inputs in Agriculture Requires a System Change’. ↩︎
‘Optimizing Water Use Efficiency and Yield of Wheat Crops through Integrated Irrigation and Nitrogen Management’. ↩︎
