Fertilizer Nitrogen and Corn Plants: Not all Volatilized Ammonia is Lost

Core Ideas Corn plants absorb volatilized ammonia from urea. Foliar area controls ammonia absorption. Not all N‐fertilizer emitted as ammonia can be considered lost.Plants can absorb NH 3 from the atmosphere through the foliage, potentially recovering part of the volatilized N from N fertilizers. To measure the extent of corn ( Zea mays L.) foliar uptake of NH 3 derived from surface applied urea at different growth stages and study the relationship between the amount of NH 3 uptake and corn leaf area, a field experiment was set up during the 2011–2012 and the 2012–2013 growing seasons. The experiment was developed in a complete randomized blocks design with four replications. Treatments consisted of five sidedress N application times (growth stages V4, V6, V8, V10, and V12) using 15 N‐labeled urea. The percentage of volatilized N (VN), the percentage of volatilized N recovered by the plant (PVNP), and the leaf area (LA) at each N application time were evaluated. Using the tray method, the VN varied from 23 to 68% of the total N applied, given these differences mainly related to climatic conditions (i.e., rainfall occurrence). On average for the two growing seasons, measured PVNP values were 3.4, 5.5, 6.2, 9.0, and 14.8% at V4, V6, V8, V10, and V12 growth stages, respectively. Approximately 90% of the total N uptake ( 15 NH 3 , by the foliage) was allocated in the leaves and 10% in the stem. We found a high correlation between LA and PVNP ( r 2 = 0.92, p ≤ 0.05). Furthermore, corn plants can take up part of the surface applied fertilizer‐derived (urea) NH 3 , up to values of 15% of the volatilized N–NH 3 .