Nitrification Inhibitor Effects on Nitrous Oxide Emission, Nitrogen Transformation, and Maize (Zea mays L.) Yield in Loamy Sand Soil in Thailand

ABSTRACT

The nitrification inhibitors (NIs) effects on soil nitrogen (N) fates and maize yields were investigated in a loamy-sand soil in Thailand. The treatments were chemical fertilizer (CF) and CF with dicyandiamide (DCD) or neem oil at two rates of 5% and 10%. Compared to the CF plot, DCD and neem oil reduced the cumulative nitrous oxide (N₂O) emission by the equivalent of 26% and 10%, respectively (P < 0.05). DCD and neem oil had a positive effect in slowing ammonium (NH₄⁺)-conversion and prolonging NH₄⁺-N in the soil with a maximum efficiency of 45% and 30%, respectively. NO₃^–N was higher in the NI plots (P < 0.05), but the effect was less pronounced later in the growing season. Adding the NIs increased maize yields and N uptake, but was only significant (P < 0.10) for neem oil. Results indicate that applying NIs is an effective method to mitigate soil N losses and enhancing N use efficiency in a tropical, agricultural field.

KEYWORDS:

• Maize
• nitrification inhibitor
• soil inorganic N
• soil N₂O emission
• tropics

Acknowledgments

We are very thankful for the instrumental support provided by the Department of Biology, Chulalongkorn University. Additional assistance was also provided by Dr. Tassanee Prueksasit, Mr. Teera Somwang, Ms. Nipawan Sananwai, and Mr. Punlop Wimolsoponkitti.

Additional information

Funding

We wish to acknowledge funding by the Kasetsart University Research and Development Institute (KURDI) and the Science Research Fund (ScRF) of the Faculty of Science, Kasetsart University, for supporting this research.