Latest INREC survey shows 142% growth in cover crops and steady conservation gains since 2017.

Iowa farmers continue to make steady gains in utilizing conservation practices such as no-till and cover crops that improve water quality, according to the most recent report of conservation practice adoption levels in Iowa.

Since 2017, the Iowa Nutrient Research and Education Council’s (INREC) Nutrient Reduction Survey has tracked on-farm conservation practices implemented by farmers across the state, providing one of the strongest datasets in the country, says Ben Gleason, INREC executive director. 

The 2024 survey shows adoption of cover crops has grown nearly 142% statewide since 2017. 

“Even through challenging years, more farmers are finding ways to fit cover crops into their field management systems and keep soil covered year-round,” says Gleason.

No-till acres have increased by 22% since 2017, totaling over 9.4 million acres, the survey found. Benefits of no-till include improved soil structure, increased organic matter, and reduced erosion and phosphorus loss.

Phosphorus (P) use and management also continue to show strong farmer commitment, with almost 95% of farmers applying P only when at or below optimum soil test levels.

“The 2024 survey results reinforce Iowa’s leadership in both agricultural production and conservation. We continue to see a steady increase in cover crop use and no-till soil management practices, even in a tough ag economy,” said Iowa Secretary of Agriculture Mike Naig. “IDALS will continue working alongside our public and private partners to support new rural and urban conservation practices, and build upon existing projects, to advance the Iowa Nutrient Reduction Strategy. We’ll continue looking for ways to break down barriers, reduce red tape and explore new approaches to streamline the process and make it easier for farmers to say yes to conservation.” 

INREC compiles the report using a statistically sound survey of farms across Iowa with help from ag retailers and certified crop advisors to measure and demonstrate progress in conservation practices.

“The year-to-year results have never shown dramatic jumps up or down due to other variables like weather and economics. Instead, they show a steady adoption of conservation practices revealing farmers’ and landowners’ commitment to Iowa’s soil and water quality,” said Gleason. 

Gleason


Cover crop growth

Iowa farmers planted more than 3.87 million acres of cover crops in 2024, a gain of about 32,000 acres from the previous year. Prior to the 2013 adoption of the Iowa Nutrient Reduction Strategy, Iowa’s cover crop acreage was estimated at only around 10,000 acres.

Cover crops now cover about 16.7% of Iowa corn and soybean acres. Rye remains the primary cover crop planted by Iowa farmers with 3.46 million acres. 

Cover crops protect soil from erosion, hold nutrients and build organic matter, aligning with goals of the Iowa Nutrient Reduction strategy. Research from Iowa State University shows that rye cover crops can reduce nitrate losses by around 60% compared to no cover crop in a corn-soybean rotation over a period of four years. 

The survey found that commercial nitrogen rates in Iowa have remained relatively steady since the survey began even as per acre yields continue to grow, reaching a record 211 bushels per acre in 2024.

“That tells us farmers are applying what the crop needs,” said Gleason. “It also shows a good balance between keeping yields up and protecting water quality.” 

The average commercial rate in 2024 was 179.2 pounds per acre for corn following soybeans and 205 pounds per acre on continuous corn, in line with Iowa State University’s optimum economic returns to nitrogen recommendations.

Efficiency of nitrogen usage has also improved, with recommended rates equaling about 0.7 pounds of nitrogen per bushel of corn today compared to 1.2 pounds per bushel 30 years ago, according to ISU agronomy professor Mike Castellano.

Trends indicate farmers are also applying nitrogen responsibly in terms of timing and application methods, utilizing split and in-season applications to deliver nutrients when crops need them. Year-to-year variability in application practice reflects larger factors, such as fertilizer price swings, yield expectations, soil tests and weather challenges.

Spring application of manure is also slowly increasing as farmers look to better match nutrient release with crop needs, according to the INREC report.

Soil testing remains central to phosphorus management, with nearly 80% of fields tested for phosphorus and 95% of applications occurring when soil-test levels are at or below optimum levels, ensuring efficient use of nutrients and minimizing environmental impact. 

Regarding tillage practices, the survey found the trend continues toward less intensive tillage practices as farmers look to improve soil health, protect water quality and support long-term productivity. 

No-till is especially common before soybeans, with 55.3% of soybeans planted in a no-till system, the highest mark since the survey began. More than 50% of corn acres were planted using either no-till or conservation tillage.