Nitrate Leaching from Grassed Lysimeters Treated with Ammonium Nitrate or Slow‐Release Nitrogen Fertilizer

Publisher Website
Google Scholar
Abstract
Nitrate leaching is a potential in humid regions when crops and forages are fertilized. This study was conducted to compare NO3 leaching with two different N fertilizer formulations applied to forages. For 11 yr, ammonium nitrate (AN) was applied to a large (8.1 m2 surface area), undisturbed, monolithic lysimeter Y101B at an annual rate of 168 kg N ha−1, and methylene urea (MU), a slow‐release fertilizer, was applied to a similar lysimeter (Y101D) at the same rate. Nitrate‐N concentrations in the percolate from these 2.4 m‐deep lysimeters were measured weekly. Even though NO3‐N levels increased steadily with the AN applications, the greatest increases occurred during the eighth year of treatment and reached levels above 20 mg L−1. With the MU, NO3‐N concentrations remained relatively constant until after 8 yr of treatment, reaching concentrations of 6 mg L−1. The highest rates of annual NO3‐N transport in percolate were 42.3 and 12.1 kg ha−1 from lysimeters treated with AN and MU, respectively. (Losses from NH3 volatilization were measured at 12.0 and 44.8 kg N ha−1 for AN and MU, respectively.) Nitrate‐N transport in percolate varied seasonally with the greatest amounts being moved during the late winter‐early spring. Following 11 yr, the NO3‐N concentrations in each lysimeter declined to approximately 1 mg L−1. Based on this study with a 168 kg N ha−1 annual application rate, less NO3‐N leaching will occur when a slow‐release N fertilizer, such as MU, is applied to forages than when AN is applied.

This publication has 0 references indexed in Scilit: