Nitrogen source affects in-season nitrogen availability more than nitrification inhibitor and herbicide in a fine-textured soil

Nitrogen (N) fertilizer management continues to be challenging due to potential nitrogen losses under variable weather conditions. This study aimed to evaluate the performance of nitrification inhibitors, nitrogen sources, and herbicides on in-season nitrogen availability and agronomic indicators. A 2 site-year field experiment was conducted in silty-clay loam soil in the maize (Zea mays L.) phase of a maize-soybean rotation in Central Nebraska. The study included two herbicide treatments (Acuron and Resicore) and four nitrogen treatments: (1) anhydrous ammonia with a nitrification inhibitor, (2) anhydrous ammonia without a nitrification inhibitor, (3) urea with a nitrification inhibitor, and (4) urea without a nitrification inhibitor. Nitrogen sources had a more significant effect on NH4+-N retention (300%-340% higher in anhydrous ammonia vs. urea) than nitrification inhibitors (14%-50% higher with inhibitor vs. without inhibitor) and herbicides. Similarly, nitrogen sources significantly affected NO3--N formation (58%-64% lower in anhydrous ammonia vs. urea) compared with nitrification inhibitors (7%-27% lower with inhibitor vs. without inhibitor) and herbicides. Nitrification inhibitors did not affect agronomic indicators. However, anhydrous ammonia increased grain yield by 1.1 Mg ha-1, partial factor productivity by 6 kg grain kg-1 N, agronomic efficiency by 5.5 kg grain kg-1 N, aboveground biomass N-uptake by 34 kg N ha-1, grain N-uptake by 15 kg N ha-1, nitrogen recovery efficiency by 33%, and residual total inorganic N by 6-40 kg N ha-1 compared to urea. These findings suggest that using the right fertilizer source, followed by nitrification inhibitor and herbicide, can be an effective strategy for conserving nitrogen and improving nitrogen use efficiency in maize. Nitrogen source conserved nitrogen more than nitrification inhibitors and herbicides.Anhydrous ammonia retained four times higher soil NH4+-N than urea.Nitrification inhibitors did not affect agronomic indicators and maize grain yield.Anhydrous ammonia improved agronomic indicators and maize grain yield more than urea.Right nitrogen source can improve NUE, followed by nitrification inhibitors and herbicides.