Study shows soil nutrient decline nationwide

Study shows soil nutrient decline nationwide

New analysis reveals significant decline in soil nutrient levels nationwide over past 10 years.

Although yields have been great over the past couple of years, farmers should avoid being lulled into a false sense of security and recognize that a lack of soil nutrients must be addressed to ensure sufficient yields in future growing seasons.

As farmers across the country look for the most economical ways to feed a growing population, they need to recognize the importance of soil fertility in maximizing crop yields and their business's return on investment. That observation comes from Dr. Robert Mullen, chief agronomist for PotashCorp. 


Studying trends in fertilizer use over the past 10 years
Soil nutrient data shows that over the last decade, more and more soils across the country are testing below the critical level for phosphorous and potassium as nutrients are removed faster than fertilizer nutrients are added. Although yields have been great over the past couple of years, farmers should avoid being lulled into a false sense of security and recognize that a lack of soil nutrients must be addressed to ensure sufficient yields in future growing seasons.

To demonstrate the decline in soil nutrient levels, eKonomics from PotashCorp, an online resource dedicated to providing farmers with relevant, easy-to-understand agricultural information, released a nationwide nutrient balance analysis highlighting the nutrient application deficit across the United States. Led by Mullen, the analysis looked at key fertilizer statistics to help farmers understand what conditions are like in their area and what they should be prepared for in the future.

Nutrient balance: an overview for the state level
To dig further into nutrient trends, eKonomics analyzed USDA numbers for crop acreage and yield, AAPFCO (American Association of Plant Food Control Officials) fertilizer sales numbers and USDA animal production numbers to account for manure. While this information has been accessible for years, yet never analyzed on an annual basis, eKonomics has created the first aggregated resource with the ability to draw relevant conclusions about nutrient balance at the state level.


It's critical to test soil regularly, and fertilize for high yields
In Iowa, for example, the leading producer of corn and second-largest producer of soybeans in the U.S., USDA harvest information shows potassium removal trends have increased 35% since 1975. Combining this number with AAPFCO fertilizer sales, which have decreased 7%, reveals that potassium balance has decreased 434%. This continual decrease in potassium balance aligns with data released by the International Plant Nutrition Institute (IPNI), revealing the percentage of Iowa soils testing below the critical level for potassium has grown from 47% in 2005 to 55% in 2010.

"If you're not prioritizing soil testing and fertilizer, it's not a question of if your yields and bottom line will be impacted by decreased nutrient levels, but when," says Dr. Mullen. "As nutrient balances trend downwards across the country, it's important to conduct soil tests on a regular basis to ensure your fields are above the critical levels for key nutrients, and to be mindful of your higher yields when making fertilizer decisions."

Understand the numbers behind nutrient balance trends
To clearly illustrate this newly aggregated research and give farmers actionable data helpful in their regions, eKonomics has displayed the data in an interactive map that features regional data for 40 individual states and seven Canadian provinces. To view the in-depth state-by-state analysis, visit the eKonomics site at and join the discussion on Twitter @eKonomics_PCS.

Nutrient management should meet the needs of each field
Soil testing and nutrient balance information presented is statewide and can differ within regions of every state and province, notes Mullen. Nutrient management should occur on a site-specific basis where management objectives and the needs of individual fields and, in many cases, areas within fields, are recognized. Therefore, a general soil test summary like this one cannot reflect the specific needs of individual farms.

Its value lies in calling attention to broad nutrient needs, trends, and challenges, and in motivating educational and action programs that are in turn relevant to growers and their advisers.

As the world's largest crop nutrient company, PotashCorp plays an integral role in global food production, he adds. The company produces the three essential nutrients required to help farmers grow healthier, more abundant crops. "With global population rising and diets improving in developing countries, crop nutrients such as potash, phosphates and nitrogen offer a responsible and practical solution to help produce the food we need, from the land we have."

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