NITROGEN MOVEMENT WITH FURROW IRRIGATION METHOD AND FERTILIZER BAND PLACEMENT

Alternate-furrow irrigation has been proposed as a method to increase irrigation water use efficiency, increase capture and storage of rainf all during the irrigation season, and decrease deep percolation of wat er. We hypothesized that less fertilizer leaching would occur if the a pplied fertilizer were spatially separated from the irrigation water i n a furrow irrigation system. A study was conducted on a Fort Collins loam (fine-Loamy, mixed, superactive, mesic Aridic Haplustalf) in 1994 and 1995 near Fort Collins, CO. Nitrogen uptake by corn (Zea mays L.) and N leaching were determined with alternate-furrow and every-furrow irrigation water applications, each with fertilizer bands of N-15-enr iched (NH4)(2)SO4 placed either in the row or in the furrow. In 1994 f ertilizer N leached to approximate to 1 m for the every-furrow irrigat ion with fertilizer placed in the irrigated furrow, but to 0.5 m or le ss for the other treatments. In 1995 the fertilizer leaching was simil ar among the treatments because of less irrigation and more rainfall d uring the growing season. There were no statistically significant diff erences for irrigation water placement effects on plant biomass or tot al N uptake, indicating that alternate-furrow irrigation is not detrim ental to crop production compared with every-furrow irrigation for sim ilar applications of water. This study showed that placing fertilizer in the nonirrigated furrow of an alternate-furrow irrigation system or placing fertilizer in the row with either alternate- or every-furrow irrigation has the potential to decrease fertilizer leaching without r educing crop productivity.