Response Of Irrigated Corn To Nitrogen Fertility Level Within Two Tillage Systems

Irrigated farmers generally utilize intensive tillage to manage crop residues and prepare a seedbed for com. Nitrogen fertilizer management practices have been developed for conventional-till (CT) irrigated com production. Little information is available for no-till (NT) and reduced-till (RT) irrigated com production systems. This paper compares the response of irrigated continuous com to N fertility level under CT and NT or RT production systems on a Fort Collins clay loam soil from 1999 through 2001. Grain yields increased similarly with increasing available N level [soil NO3-N (0-3 ft) plus fertilizer N added] in 1999,2000, and 2001 for both tillage systems. The CT com yields were greater than the RT or NT com yields in 1999 and 2001, respectively. Based on the results from this study, similar N levels were required. for optimum com yields in all tillage systems. Additional years of data are needed to determine if NT will require a higher level of N fertilizer input than CT to optimize com grain yields. Current N fertilizer recommendations for CT irrigated com production would appear to be adequate for irrigated NT com production