How big is the orchard footprint?

The galvanized wire used for trellises might contribute significantly to the environmental footprint of an orchard because of the large amount of energy used in its manufacture.

Washington State University researchers are assessing the environmental impact of the typical Washington apple orchard.

Dr. Usama Zaher, biological systems engineer, is developing a life cycle assessment, which will look at every impact of producing apples in Washington, from the raw materials (including nursery trees) to removal of the trees.

Apples and other tree fruit crops inherently have a minimal environmental footprint, says David Granatstein, WSU sustainable agriculture specialist.  To grow apples, you could simply plant a seed, water it from a bucket as necessary, remove weeds by hand for the first few years, pick the fruit, and throw away the core. In fact, the process might have a positive environmental impact because trees remove carbon dioxide from the air and store it in the wood.

It’s when you add management to make the orchard more economically viable and raise productivity that the footprint increases, Granatstein says. Inputs such as fertilizer, irrigation systems, trellis materials, and the use of equipment all affect the environment.

A footprint is simply a measure of the effect of a system on one or more environmental factors, and it’s not very useful unless you have something to compare it to, Granatstein says. Plus, it only measures negative impacts on the environment.

Food miles

Food miles are an even more simplistic measure of environmental impact, focusing specifically on ­transportation distance of the product to market.

“Food miles don’t account for the form of transportation (truck vs. train) nor the energy used in production of the food,” Granatstein said. “In some regions, it takes less energy to grow a particular crop, even though it may be further from a market.”

Washington apples might clock up more food miles than local fruit when shipped to the East Coast, but if they’re produced and stored using hydropower rather than fossil fuels, their real environmental impact might be lower.

A valid comparison of food miles should consider the consumers driving to the grocery store to buy the food, Granatstein said. A semi-truck uses about one-tenth of the fuel per ton-mile that a shopper driving a GMC Suburban to the grocery store uses, and a train uses a tenth of the fuel that a truck uses.

“With a car, most of the energy goes to moving the car; the groceries are a fraction of that. It might be that walking to the store for groceries is one of the larger positive impacts a person can have on the carbon footprint of their food,” Granatstein said. “Growers can reduce their footprints, too, but consumers need to understand their role.”

Science-based

A life cycle assessment, a science-based process developed initially for manufacturing industries, can be used to assess all the different impacts of a production process, such as growing apples, to get a more complete picture. It uses hard numbers and covers a wide range of potential impacts relating to human health, the quality of the ecosystem, change of climate, and resources, such as nonrenewable energy.
Researchers at Lincoln University in New Zealand took this approach in response to food miles criticism about apples imported into the United Kingdom. Their calculations showed that fresh crop New Zealand apples exported to the United Kingdom resulted in lower energy use and carbon dioxide emissions than apples grown in the United Kingdom and stored for five months. But a similar study done in Germany by Michael Blanke and Bernhard Burdick, found the opposite, with imported fruit requiring 27 percent more energy than German fruit stored for six months.

Granatstein said the devil is in the details. Each study has its assumptions, and those must be made clear before any conclusions can be drawn.

A life cycle assessment can show how two different systems compare or can document how a system changes over time, but might be most useful for identifying where changes can be made to reduce impacts while improving profitability, Granatstein said.

For example, it might show that switching to electric machinery would greatly reduce the carbon footprint, but an LCA also could look at the energy required to build electric equipment versus a traditional tractor, which is known as the embedded energy. WSU’s LCA for apples will be linked to a database showing what the impact might be for a certain size of tractor, for example.

One of the bigger impacts of modern high-density orchards might be the manufacture of the galvanized wire used in the trellis, which has a big LCA footprint because of the high energy use, Granatstein said. “None of us thought about this when we switched to that system.  An LCA tool can help evaluate alternatives, such as a nylon wire, to see if they improve things.”

Corporate sustainability

There’s been a push for corporate sustainability and for large companies, such as Walmart, to ask suppliers to demonstrate how the products they are buying fit into the sustainability goals they’re trying to achieve. Sustainability is beginning to merge with food safety in that food safety auditors can also do some sustainability audits.

As more members of the food system require this type of information, the LCA will provide them with defensible information on the sustainability of their products, Granatstein said. It’s a way to balance the positive attributes of fruit production against the footprint. LCA procedures are defined under the International Organization for Standards’s ISO 14040 and can be certified.

Zaher said that as he compiles the apple LCA, he is looking at three phases in the life of the orchard: establishment, training, and the productive years. He’s trying to take a global view and will include the production of nursery trees before they are transferred to the orchard, as well as removal of the orchard at the end.

“The idea is to go into this detail to see what’s the really sensitive part that contributes most to the footprint or emission,” he said.

The three main greenhouse gases, other than water vapor, are carbon dioxide, methane, and nitrous oxide. Agriculture is responsible for only 2 percent of U.S. carbon dioxide emissions, but it emits 80 percent of the nitrous oxide.

Zaher said the greatest environmental impact in apple production is likely to be nitrous oxide emissions from fertilizer applications because nitrous oxide has a far more serious effect than carbon dioxide on global warming. The second greatest impact in orchards is likely to be carbon dioxide generated by equipment use.

Zaher hopes to complete the LCA by July this year and will make it available initially as an Excel spreadsheet that is easy for growers to use. The one-year project is funded by WSU’s Center for Sustaining Agriculture and Natural Resources.