Masters Theses

Orcid ID

https://orcid.org/0000-0002-2956

Date of Award

5-2024

Degree Type

Thesis

Degree Name

Master of Science

Major

Environmental and Soil Sciences

Major Professor

Nutifafa Adotey

Committee Members

Daniel Yoder, Lori Duncan, Debasish Saha, Frank Yin

Abstract

The efficiency of urea-based fertilizers is substantially reduced through nitrogen (N) losses via ammonia volatilization. Soil pH, clay content, soil organic matter (SOM), and field capacity can affect ammonia loss. Incubation experiments were conducted on eight soils using a controlled environment system to study the effects of soil properties on ammonia volatilization from urea and urea ammonium nitrate (UAN) applied at 134.5 kg N/ha. Each experiment was set up as a randomized complete block design with four replicates. Ammonia loss was measured on 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, and 16 DAF (days after N application). Cumulative losses of ammonia from UAN and urea ranged from 1.4 - 18.1 % and 10.5 - 26.5 % of total N applied, respectively. Cumulative ammonia losses from urea were higher than UAN in six soils, but the losses were similar for both urea and UAN in the remaining soils. Stepwise regression analysis predicted soil pH and clay content as the most parsimonious model for ammonia loss from both urea and UAN applications. The same experimental setup was used to evaluate the efficacy of different enhanced efficiency N fertilizer (EENF) products in mitigating ammonia volatilization losses in two soils highly susceptible to ammonia volatilization losses. The EENF sources included Urea+ANVOLTM, UAN+ANVOLTM, ESN®, SUPERU®, and urea+Excelis® which were surface-applied at 134.5 kg N/ha. Cumulative ammonia loss from the EENF products ranged from 3.3 – 10.6 % in soil 1 and 2.2 – 16.1 in soil 2 (% of applied N). Treated urea products were effective in reducing ammonia volatilization loss (% of applied N) by 60.63 – 87.62 and 32.26 – 90.96 % for soils 1 and 2, respectively, when compared to untreated urea. Similarly, the treated UAN reduced ammonia volatilization loss by 26.90 and 69.51 in soils 1 and 2, respectively when compared to untreated UAN. The effectiveness of the EENF treatments in both soils was: ESN® > UAN+ANVOLTM > urea+ANVOLTM > urea+Excelis® > SUPERU®. Reliable EENF products are a viable tool to reduce N losses as ammonia, regardless of soil properties.

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