Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 16, 1997
Publication Date: N/A
Interpretive Summary: Nitrate leaching into the groundwater can be a problem in irrigated corn fields. We examined the possibility of reducing leaching by restricting irrigation water to alternate furrows with fertilizer placement in the non-irrigated furrow. For such a scheme to work root growth in the non-irrigated furrow must be great enough to take up the applied fertilizer rThis study looked at root production under a combination of water and fertilizer placements. In this two year study, spring rains were greater than normal providing adequate moisture for early season root growth in both the irrigated and non-irrigated furrows. When the non-irrigated furrow began to dry, root growth increased compared to the wet furrow in both years. In only one of the two years, however, did root growth increase in the fertilized compared to the unfertilized furrow. When early season rains were present fertilizer uptake was not limited by a lack of roots in the non-irrigated furrow.
Technical Abstract: Proper management of water and fertilizer placement in irrigated corn (Zea mays L.) has the potential to reduce nitrate leaching into the ground- water. Potential management practices tested in a two year field experiment included row or furrow fertilizer placement combined with every or alternate furrow irrigation. To understand how fertilizer availability to plants could be affected by these management practices, root growth and distribution in a Ulm clay loam soil were examined. Spring rains were greater than normal in both years providing adequate moisture for early root growth in both irrigated and non-irrigated furrows. As the non-irrigated furrow began to dry, root biomass increased as much as 126% compared with the irrigated furrow. The greatest increase was at lower depths, however, where moisture was still plentiful. When early season moisture was available, roots proliferated throughout the soil profile and quickly became available to take up fertilizer N in both irrigated and non-irrigated furrows. Root growth responded positively to fertilizer placement in the furrow in 1996 but not in 1995. Excessive N leaching in 1995 may have limited the response to fertilizer N.