ARS | Publication request: Use of 15N labeled Urea to Study Nitrogen Use Efficiencies in a Forage Corn-Oat Rotation Grown on Clay and Sandy Clay Loam Soils of Mexico

Submitted to: Soil and Water Conservation Society
Publication Type: Abstract Only
Publication Acceptance Date: May 7, 2009
Publication Date: July 11, 2009
Citation: Cueto-Wong, J., Delgado, J.A., Figueroa, U.V., Quiroga-Garza, H.M., Trucios-Casiano, R. 2009. Use of 15N labeled Urea to Study Nitrogen Use Efficiencies in a Forage Corn-Oat Rotation Grown on Clay and Sandy Clay Loam Soils of Mexico. Soil and Water Conservation Society.

Technical Abstract: Nitrogen (N) is applied in large amounts to sustain high forage yield and quality to feed a dairy cattle population surpassing 440,000 heads in Comarca Lagunera, Mexico (25° 32´ N, 103° 14´W and 1150 masl). Traditional farm practices across this region overaplly organic (manure) and fertilizer N. We need additional information about the fate and transport of the applied N. 15N-labeled fertilizer was used to evaluate N recovery of fertilizer applied at planting and during the first irrigation with N fertilizer used alone or in combination with manure applications. The total N rate from fertilizer applications or from combinations of N fertilizer and manure were 300 kg N ha-1 for each treatment combination. The recovery of the 15N fertilizer was also monitored in the subsequent forage oat crop. There were no significant dry matter yield changes due to either N fertilizer application or N source in forage corn or oats. Isotopic analysis results show that average N fertilizer recoveries were 35% for the forage corn. All recovery data will be presented. These studies show that manure applications can sustain higher yields, but that more than 300 kg N ha-1 will only increase the losses of reactive N to the environment. These results show that traditional practices need to be modified to apply less N if underground water quality is to be conserved across the region.