What is nitrogen use efficiency (NUE)?
Nitrogen use efficiency in crops refers to the crop’s ability to convert applied nitrogen (N) into harvested grain. A higher NUE means a greater proportion of the N applied is taken up and utilised by the plant, resulting in improved growth, reduced wastage, and lower emissions.
In maize, NUE typically ranges between 30% and 50%, meaning nearly half of the N applied is lost to the environment.
NUE can be further broken down into two core components:
- Nitrogen uptake efficiency (NUpE) – the amount of applied N that the plant absorbs from the soil.
Formula: NUpE = Total N in plant / Total N applied - Nitrogen utilisation efficiency (NUtE) – how efficiently the absorbed N is used to produce grain.
Formula: NUtE = Grain yield / Total N in plant
Together, these components make up N nitrogen use efficiency:
NUE = NUpE × NUtE
What influences NUE?
NUE is affected by plant, soil, climate, and management-related factors. Certain maize hybrids naturally absorb and use N more efficiently. A more extensive or deeper root system can access more N in the soil.
Soil properties such as texture, organic matter content, pH, and CEC (cation exchange capacity) all influence NUE. Excessive rainfall can cause N losses through leaching or denitrification.
Temperature affects microbial activity, nitrification, and N uptake rates, while drought stress restricts N uptake by limiting root activity and water availability. Over-application results in wastage, while under-application restricts yield potential.
Applying N closer to the crop’s peak demand period, such as side-dressing at the V6–V8 growth stages, improves efficiency. The type of fertiliser used, along with inhibitors and stabilisers, also plays a significant role.
Other practices such as tillage systems, crop rotation, and the use of cover crops influence N use efficiency as well.
How can NUE be improved?
- Split N applications to align more closely with crop demand and reduce losses from leaching or volatilisation.
- Use enhanced efficiency fertilisers like Kynoplus Pro to reduce volatilisation losses.
- Leverage GPS-guided equipment and variable-rate technology to apply nitrogen precisely where it’s needed.
- Implement cover crops to capture and retain residual nitrogen, reducing losses.
- Practise crop rotation, especially with legumes, to increase nitrogen availability in the soil.
- Select maize hybrids bred for high nitrogen use efficiency.
- Reduce tillage to help maintain soil structure and preserve organic matter.
- Conduct soil testing to monitor available nitrogen and organic matter content.
How does Kynoplus Pro impact NUE?
Kynoplus Pro represents the latest generation of urease inhibitors and plays a direct role in reducing N losses through volatilisation. More N remains in the soil in plant-available forms (ammonium/NH₄⁺), making it accessible to the crop when needed most.
This enhances the plant’s N uptake efficiency (NUpE), reduces the likelihood of other N losses, and ensures less wastage, ultimately giving you a higher yield per unit of N applied.
Beyond just protecting your N investment, Kynoplus Pro also offers greater flexibility in N management, allowing for more options in timing, rates, and application methods. It further supports environmental sustainability by reducing greenhouse gas emissions and N movement into water systems.
Conclusion
NUE is influenced by numerous factors, but by applying the right practices and using advanced solutions like Kynoplus Pro, significant improvements can be achieved. Research shows that Kynoplus Pro increases N uptake in plants, with a clear link to improved yields.
For more information, reach out to the expert team at www.kynoch.co.za.
