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Published on: March 21, 2016
Synthesis of artificial humic acid-urea complex improves nitrogen utilization
Yongxu Jin1, Xi Zhang1, Yue Yuan1
1School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin, 150030, China; Heilongjiang Provincial International Joint Laboratory of Smart Soil, Harbin, 150030, China.
This study developed a novel artificial humic acid urea fertilizer that improves nitrogen (N) use efficiency. The new fertilizer releases N effectively in early stages and retains it long-term, reducing agricultural N pollution.
Area of Science:
- Agricultural Science
- Soil Science
- Environmental Chemistry
Background:
- Conventional nitrogen (N) fertilizers cause soil N enrichment and loss through runoff, volatilization, and leaching.
- Artificial humic acid (AHA) can enhance fertilizer efficiency, but its heterogeneity hinders analysis and utilization.
- Developing novel N fertilizers is crucial for sustainable agriculture and mitigating environmental pollution.
Purpose of the Study:
- To fractionate artificial humic acid (AHA) to improve its structural analysis and utilization efficiency.
- To prepare and evaluate novel AHA-urea complex fertilizers for enhanced nitrogen (N) release and retention.
- To assess the impact of these fertilizers on soil microbial communities and N sequestration.
Main Methods:
- Fractionation of AHA using a continuous dissolution method at varying pH levels.
- Preparation of AHA-urea complex fertilizers (A-HAU) at specific pH conditions (e.g., pH 3-4).
- Soil incubation experiments to measure N release (NH4+-N, NO3--N), N content over time, and analyze soil microbial community structure.
Main Results:
- Four AHA fractions with distinct aromatization degrees and molecular weights were obtained, with the highest aromatization at pH 3-4.
- AHA-urea fertilizer prepared at pH 3-4 (A-HAU3-4) significantly improved NH4+-N release (38.32% on day 7) and NO3--N release (10.30% on day 14) compared to urea.
- A-HAU3-4 provided sustained inorganic N supply (days 3-14) and maintained higher soil N content (day 70), increasing beneficial soil bacteria (Proteobacteria, Actinobacteriota) and enhancing N utilization and sequestration.
Conclusions:
- Artificial humic urea fertilizers with high aromatization or low molecular weight are effective for improving initial N utilization and long-term N fixation in soil.
- This strategy offers a promising approach to mitigate agricultural nitrogen pollution and promote soil health.
- The developed method for AHA fractionation and fertilizer preparation has significant ecological implications for sustainable agriculture.
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