In a field experiment, a clay-and-biopolymer fertilizer used with two nutrient-releasing bacteria lowered nitrous oxide emissions compared with conventional urea.
Researchers tested two urea-loaded materials made from nanoclay, acrylic-based polymers and either maize flour or mango kernel flour. The materials were used with cultures of Lactococcus lactis and Pseudomonas aeruginosa, which the study used to help release phosphorus and zinc for plant uptake.
In a randomized field experiment with 10 treatments, the microbe-containing composites supplied 75% of the recommended nitrogen dose and were compared with conventional urea supplying the full recommended dose. The combined treatments maintained more sustained soil nitrogen levels, increased phosphorus and zinc in wheat and maize grain and straw, and reduced nitrous oxide emissions in both crops.
What the fertilizer changed
Treatments combining the composites with both bacterial cultures maintained higher and more synchronized levels of ammoniacal and nitrate nitrogen in the soil than conventional urea. They also significantly increased phosphorus and zinc content in the grain and stover of both wheat and maize.
Compared with the full recommended dose of conventional urea, these treatments reduced cumulative nitrous oxide emissions by 17–29% in wheat and 21–24% in maize. The maize-flour-based composite showed the greatest emissions-mitigation potential. The composites absorbed about 68 grams of water per gram of material for the maize-flour version and about 62 grams per gram for the mango-kernel-flour version after 24 hours.
Why the results matter
Conventional prilled urea can lose nitrogen through leaching, denitrification and ammonia volatilization, reducing how much reaches crops and contributing to environmental pollution. In this field study, combining a lower nitrogen application with the clay-based material and bacterial cultures was associated with better plant nutrient content and lower nitrous oxide emissions than the full conventional urea treatment.
The results point to a possible way to coordinate nitrogen supply with crop needs while also improving phosphorus and zinc uptake in two important cereal crops. The study does not establish how the composites would perform across different soils, climates, seasons or farming systems.
Evidence and caveats
The evidence comes from a randomized complete block field experiment comparing 10 treatments in a maize–wheat cropping system, along with laboratory analyses confirming the materials' structure and water absorption. The abstract reports significant differences in nutrient content and emissions, but does not give the field location, experiment duration, number of replicates or detailed effect sizes for nutrient uptake.
The findings therefore support the performance of these treatments under the tested field conditions, not a universal result for all farms. The abstract also does not report longer-term effects on soil health, repeated-season performance, economic costs or other nitrogen losses such as ammonia volatilization and nitrate leaching.
