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Use BMPs to protect the environment

Overall, potatoes do not contribute much in the way of greenhouse gas emissions even though it is an intensively grown crop requiring multiple passes with equipment. Nevertheless, because the crop most often grows on sandy or high drainage soil, and often under irrigation, the environment can be affected by nitrogen losses due to leaching, and excess nitrogen can lead to increased nitrous oxide emissions.


April 6, 2009
By Rosalie I. Tennison

Topics

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Sound crop management and optimum fertilizer management minimizes the carbon footprint per pound of potato produced.


 

Overall, potatoes do not contribute much in the way of greenhouse gas emissions even though it is an intensively grown crop requiring multiple passes with equipment. Nevertheless, because the crop most often grows on sandy or high drainage soil, and often under irrigation, the environment can be affected by nitrogen losses due to leaching, and excess nitrogen can lead to increased nitrous oxide emissions. Diligent growers can minimize these issues with careful use of products and adopting Best Management Practices (BMPs), according to industry researchers.  “A fertilizer program that reduces the application of excess nitrogen is considered helpful in reducing nitrous oxide emission,” states Dr. Tom Bruulsema, director, northeast region of North America for the International Plant Nutrition Institute. “Potatoes are heavily dependent on all three major nutrients and without them you can’t sustain production.”

However, adds the Guelph-based researcher, using those nutrients carefully, particularly nitrogen, will still result in a good crop and minimize problems in the environment.

Bruulsema explains that turning forested land into agricultural land results in less storage of carbon dioxide, but the world need for food does not support returning agricultural land to forest land. Therefore, he suggests that growers need to be diligent in their efforts to reduce emissions and prevent other negative environmental effects that could result from agricultural operations. “Growers need to apply the right source of nutrients at the right rate, at the right time and in the right place,” Bruulsema continues. “Perhaps growers could consider using a controlled release product as a nitrogen source. It could potentially reduce the amount of excess nitrogen added to the soil. There will also be less chance of leaching because the nitrogen is delivered to the plant slowly through the growing season.”

While Canadians may not always welcome the first signs of winter, the country’s cold climate gives growers an unexpected bonus when it comes to environmental protection. “In general, Canadian soils can contribute to fixing and holding carbon because of the cold climate,” explains Dr. Kim Polizotto, senior agronomist with the Potash Corporation of Saskatchewan. “The shorter growing season, cold climate and long winters make it easier for soils to hold onto carbon. The potato crop captures a lot of carbon dioxide from the air and turns it into valuable starch, while the other crops in the rotation contribute more carbon to the soil.”

“A good crop rotation managed with best practices maintains as much organic matter as possible in the soil,” adds Bruulsema. “Building and maintaining soil organic matter keeps carbon dioxide out of the atmosphere, and supports high potato yields. Combining sound crop management with the right fertilizer management minimizes the carbon footprint per pound of potato produced.”

Bruulsema advises growers to follow recommended guidelines on plant nutrition from universities, provincial departments of agriculture and their crop input dealer. Also, it is worthwhile to ask annually if there are new recommendations because ongoing research continually fine-tunes recommendations and what was recommended a decade ago may no longer be valid. “Every nutrient should be used at the optimum and not in excess,” he continues. “The goal is to minimize nitrate leaching and nitrous oxide emissions, while supporting high-yield crop production.” He adds that properly maintained and calibrated equipment will ensure the recommended amount is applied. He also reminds growers to match rates specific to the needs of the cultivar.

Polizotto echoes the advice about ensuring accurate incorporation with properly maintained and calibrated equipment. “Consider split applications or controlled release products,” he suggests. “Higher rates can cause potential losses, but too low a rate can lead to yield reductions, so growers should set realistic goals and then do the best they can to balance the needs of the crop keeping the needs of the environment in mind as well.”

The downside he sees to controlled release products is their dependence on moisture to allow for availability of nitrogen to the plant, meaning a dry year with little rainfall could leave little nitrogen available.

Technology continues to improve and, as it does, more tools are available to growers to improve crop production. Polizotto suggests using the available tests that measure plant nutrition and soil nutrition because they give a good benchmark for how the crop is progressing and alert growers to areas that can be improved on in following crops.

“I’d like to emphasize that it is to growers’ advantage, industry’s advantage and the environment’s advantage to get this right,” Polizotto stresses. “The fertilizer industry supports research to learn how to use its products more efficiently and everything we do as growers or industry should be science-based. I don’t doubt farmers want to do their part to preserve the environment so I encourage them to seek out the latest research.” He says his company’s five key points for fertilizer BMPs hinge on environmental protection as much as proper use of nutrients. The points are: minimize environmental impact, choose the right product, apply the right amount, apply at the right time and apply nutrients in the right place to avoid run-off. In fact, BMPs are all about environmental protection.

While potatoes are only a small part of Canadian crop production, the use of BMPs contributes to minimizing nutrient losses to both water and air, while supporting a reduced carbon footprint for the production of food, fibre and fuel. These experts agree that continuous improvement in management practices depends on potato producers keeping up with recommendations based on the latest research.