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Impact of urease and nitrification inhibitor on NH 4 + and NO 3 − dynamic in soil after urea spring application under field conditions evaluated by soil extraction and soil solution sampling
Author(s) -
Kirschke Tobias,
Spott Oliver,
Vetterlein Doris
Publication year - 2019
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/jpln.201800513
Subject(s) - nitrification , urease , urea , chemistry , spring (device) , nitrogen , physics , biochemistry , organic chemistry , thermodynamics
The application of mineral nitrogen (N) fertilizers is one of the most important management tools to ensure and increase yield in agricultural systems. However, N fertilization can lead to various ecological problems such as nitrate (NO 3-) leaching or ammonia and nitrous oxide emissions. The application of N stabilizers ( i.e ., inhibitors) combined with urea fertilization offers an effective option to reduce or even prevent N losses due to their regulatory effect on ammonium (NH 4+) andNO 3-release into the soil. The present field experiment therefore aimed at soil N speciation dynamics after urea spring fertilization (225 kg N ha −1 ) in the presence of a urease inhibitor (UI), a nitrification inhibitor (NI), both inhibitors (UI+NI) or when no inhibitor was applied at all. The study focused on the distribution of N species among soil matrix and soil solution. Plant cultivation was completely omitted in order to avoid masking soil N turnover and speciation by plant N uptake and growth dynamics. Application of UI clearly delayed urea hydrolysis in the top soil, but a complete hydrolysis of urea took place within only 10 days after fertilization (DAF). Nitrification was significantly reduced by NI application, leading to higherNH 4+- N and lowerNO 3-- N concentrations in treatments with NI. Due to sorption ofNH 4+to the soil matrix a significantly larger fraction ofNH 4+was always detected in the soil extracts compared to soil solution. However, while in soil extracts the impact of NI application was less apparent and delayed, in soil solution a quick response to NI application was observed as revealed by significantly increased soil solution concentrations ofNH 4+. Because of the “asymmetric” soil phase distribution soil solutionNH 4+was predominant overNO 3-only initially after fertilization even in inhibitor treatments (≈ 8 to 10 DAF). Nevertheless, inhibitor application tended towards closer ratios ofNH 4+toNO 3-concentration in soil solution and hence, might additionally affect concentration dependent processes like plant N uptake and root development. Despite cold spring conditions urea application along with UI and/or NI did not indicate a limited supply of plant availableNH 4+andNO 3-.