Soil Enzyme Activity Behavior after Urea Nitrogen Application.

Area of Science:

• Soil Science
• Agronomy
• Microbial Ecology

Background:

• Optimizing nitrogen (N) fertilizer management is crucial for sustainable agriculture and food production.
• Understanding the interaction between N fertilizers and soil microbial activity, specifically enzyme function, is essential for developing effective agricultural practices.

Purpose of the Study:

• To investigate the impact of urea nitrogen (N) rate and application timing on soil enzyme activity in maize (Zea mays).
• To assess how single (fall/spring) versus split N applications influence key soil enzymes under different environmental conditions.

Main Methods:

• Soil enzyme activities, including fluorescein diacetate (FDA) hydrolysis, ß-glucosidase, acid-phosphomonoesterase, and arylsulfatase, were measured.
• Field experiments were conducted over three years (2014-2016) in Minnesota, USA, comparing different N application strategies under irrigated and rainfed conditions.

Main Results:

• Split N applications increased FDA activity by 10% at Waseca compared to single applications.
• Fall or spring N application decreased arylsulfatase activity by up to 19% at Becker and Lamberton.
• ß-Glucosidase and acid-phosphomonoesterase activities were not significantly affected by N application timing or rate.
• Sampling time and year significantly influenced enzyme activity, with location-specific variations observed.

Conclusions:

• Urea N application demonstrated limited effects on the measured soil enzyme activities across the studied sites.
• The findings suggest that organic nitrogen sources might be more influential on soil enzyme activity than the ammonium from urea.
• Soil enzyme activity is highly influenced by temporal factors (sampling time, year) and site-specific conditions.