Placement of Nitrogen Fertilizers for No‐Till and Conventional Till Corn1

Abstract

AbstractHigh rates of N loss have been observed from N fertilizers applied directly on the surface in no‐till corn (Zea mays L.) production systems. Field experiments were conducted at four locations over a three‐year period to determine what effects N source and N placement had on N losses in both no‐till and conventional till corn production systems. Soils used were: Stoy loam, an Aquic Hapludalf; Clermont silt loam, a Typic Ochraqualf; Avonberg silt loam, an Aeric Fragiaqualf; Chalmers silty clay loam, a Typic Argiaquoll; and Lyles fine sandy loam, a Typic Haplaquoll. Nitrogen sources used were anhydrous ammonia (NH3), urea‐ammonium nitrate solutions (UAN), solid urea and solid ammonium nitrate (NH4NO3). Placement variables used were injection of NH3 and UAN 20 cm below the soil surface and broadcasting UAN, urea and NH4NO3 on the soil surface with no incorporation. Nitrogen rates used were 0 and 165 kg N/ha.Injecting NH3, or UAN below the surface resulted in consistently higher corn grain yields than applying UAN, NH4NO3 or urea directly on the soil‐residue surface. Percent N in leaf and grain also reflected an increase in N use efficiency with subsurface N placement. Percent N in leaf was significantly higher where NH3 or UAN were injected as compared to UAN or urea surface applied.