Wallaces Farmer

Statewide soil tests indicate a deficiency of potash and phosphorus, costing some farmers an average of $20,000.

Compiled by staff

April 13, 2016

3 Min Read

Soil tests show that 40% of Iowa farm fields are critically deficient in two key soil nutrients, which is decreasing both crop yields as well as farmer income throughout the state. These are the findings of the International Plant Nutrition Institute (IPNI), which recently collected more than 4 million soil samples from farms across North America including 719,000 in Iowa and had them analyzed by both public and private laboratories.

“This landmark study shows that 40% of Iowa farms are critically deficient in phosphorus, while 45% are critically deficient in potassium,” says Dr. Robert Mullen, director of agronomy at PotashCorp, the world’s largest producer of crop nutrients.

Interactive map shows results of this study
Mullen, who oversees PotashCorp’s eKonomics research program, has created a state-by-state breakdown of the study coupling the data with historic nutrient balance trends in Iowa. You can see it by clicking on Interactive Map Shows Results of Study. The company’s eKonomics program is an agribusiness resource focusing on crop nutrients.

“At PotashCorp-eKonomics.com, farmers can view the results of the IPNI study in an easy-to-use interactive map. Plus, we’re adding critical state-specific data that Iowa farmers need to see,” says Mullen. “For example, we’re comparing fertilizer application rates to fertilizer removal rates over the last 40 years. And the emerging ‘nutrient balance’ trendline suggests Iowa’s problem could worsen over time.”

The downward trend is staggering in Iowa. While the “critically below” figures show some improvement in phosphorus, and even more so for potassium in the last five years, historically, potassium nutrient balances in the state are down 434%, and phosphate nutrient balances are down 874%.

Average farmer leaving thousands of dollars in the field
Given the importance of potash and phosphorus to crop health and yields, these figures should paint a sobering picture for Iowa farmers.

“Under current conditions, 40% of Iowa farmers are losing money because they are potassium deficient and almost half are losing out by shorting the soil of phosphorus,” Mullen adds. “When times get tough and crop prices are down, the natural tendency is to pull back on your P and K applications, but more often than not, cutting back on crop nutrients means cutting back on profits.”

The problem of this practice, experts say, is that it leaves a lot of potential yield and profit lying dormant in the field.

Use online calculator to figure your return on investment
Mullen uses the eKonomics ROI calculator to illustrate his point. “Let’s say you’re growing $3.60 corn on 350 acres with a yield potential of 200 bushels per acre. If you are below the critical level of potassium and you apply university recommended rates at today’s potash prices, you could increase your net profit by an average of $20,000.

Potash (K) is a major source of potassium and helps plants develop strong root systems giving crops greater resistance to drought, disease and insects. Phosphate (P) is the major source of phosphorus, the energizer of plant production, which increases yields.

As the world’s largest crop nutrient company, PotashCorp plays an integral role in global food production. 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,” notes Mullen.

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