by MEGAN WINSLOW, UF/IFAS
Applying fertilizer requires a careful balancing act between using too little — which can be insufficient to support plant growth — and applying too much, which wastes money and can hurt the environment.
A newly published UF/IFAS review explains how enhanced efficiency fertilizers (EEFs) like controlled-release and slow-release varieties can help farmers maximize their yields while reducing their chances of hurting their pocketbooks or the planet.
Hardeep Singh, a UF/IFAS assistant professor of cropping systems, is the corresponding author of the document, a product of the institute’s ongoing Nutrient Management Program. It was published in the Journal of Plant Nutrition and Soil Science.
“Enhanced efficiency fertilizer technology is not a one-size-fits-all solution, but it’s an important tool in a broader nutrient management strategy,” Singh said. “Long-term success depends on matching the right fertilizer to the crop, soil and climate conditions.”
Although the human population has more than doubled since 1960, food production has been able to keep up thanks to fertilizer inputs, according to the review. Fertilizers provide essential nutrients plants need to grow, including nitrogen, phosphorus and potassium.
But overall agriculture nutrient-use efficiency, a measure of how well plants use nutrients relative to yield, is low, ranging from 10% to 55%, depending on crops and conditions, according to the review. That’s because conventional fertilizers deliver nutrients quickly, so they can’t support the different stages of plant development over time.
Singh and his co-authors describe how controlled-release fertilizers (CRFs) and slow-release fertilizers (SRFs) provide nutrients gradually as plants need them. These fertilizers accomplish this through features like polymer coatings and microbial induced nutrient release, which limit water solubility and reduce losses.
The UF/IFAS researchers cite previous studies demonstrating the power of EEFs, including one study that equated EEF use with an increased nutrient-use efficiency of between 45.9% and 53.8% in wheat and between 36.2% and 45.4% in maize compared to conventional fertilizer. Other studies showed EEFs could increase tomato yields by 28.58% and rice yields by 20% compared to conventional fertilizers.
EEF use has also been shown to minimize the environmental risks sometimes associated with conventional fertilizers, including nutrient leaching, toxic nutrient concentrations and acidification of soils, according to the review. The UF/IFAS researchers reference 10 studies demonstrating the ability of EEFs to reduce nitrous oxide emissions, including by 90% in sugarcane, by 70% in sorghum and by 30% in cabbage.
Despite the many benefits of EEFs, barriers, such as grower concerns about return on investment, slow their widespread adoption: CRFs and SRFs cost about four times more than conventional fertilizers, according to the review. However, the added expense is offset by greater crop yields and lower labor costs because nutrients are sustained throughout the growing season, and fewer fertilizer applications are necessary.
Some growers are also discouraged by a lack of guidance for incorporating EEFs into their existing practices, Singh said. Florida has varied weather and soil conditions, and laboratory testing of EEFs does not always reflect field data.
“For growers who have access to localized recommendations and support, EEFs often prove to be a valuable tool,” he said. “Continued field-based research and demonstration are essential to help determine where and when the benefits truly outweigh the disadvantages.”
Based on Singh’s knowledge of Florida agriculture operations, he estimates between 20% and 30% of growers in the state use EEFs.
“Grower perceptions are gradually shifting from skepticism to cautious acceptance,” Singh said. “This change is driven by increased educational outreach, more cost-share opportunities and evidence from local trials showing improved nutrient-use efficiency and crop responses under certain conditions.”
Future work from Singh and his team includes comparing yield, nutrient-use efficiency and the different ways nitrogen is lost from soil across various fertilization rates and soil types in row crop production systems in Florida.