ARS | Publication request: Comparison of nitrogen fertilization methods and rates for sub-surface drip irrigated corn in the semi-arid Great Plains.

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 18, 2008
Publication Date: N/A

Interpretive Summary: In semi-arid areas such as western Nebraska, interest in subsurface drip irrigation for corn is increasing due to restricted irrigation allocations. However, crop response quantification to nitrogen applications with SDI and the environmental benefits of multiple in-season subsurface drip irrigation nitrogen fertigation applications instead of a single broadcast surface application close to planting time are lacking. Comparisons between the two nitrogen application methods and three nitrogen application rates were assessed in a study conducted in 2004, 2005, and 2006 at the University of Nebraska-Lincoln West Central Research and Extension Center in North Platte, NE. No grain yield or biomass response to the nitrogen application rates was observed in 2004. In 2005 and 2006, corn grain yield and biomass production increased with increasing nitrogen rates, and when nitrogen was split applied in-season grain yield, total plant nitrogen uptake, and gross return after nitrogen application increased compared to when the nitrogen was all applied close to planting time. Greater losses of nitrate-nitrogen below the root zone may have occurred when all the nitrogen was applied close to planting compared to when nitrogen was split applied in-season. Under subsurface drip irrigation systems, fertigating a recommended rate of nitrogen at various corn growth stages can increase yields, GRN, and reduce NO3-N leaching in soils compared to concentrated early-season applications.

Technical Abstract: In semi-arid areas such as western Nebraska, interest in subsurface drip irrigation (SDI) for corn is increasing due to restricted irrigation allocations. However, crop response quantification to N applications with SDI and the environmental benefits of multiple in-season (IS) SDI N applications instead of a single early-season (ES) surface application are lacking. The study was conducted in 2004, 2005, and 2006 at the University of Nebraska-Lincoln West Central Research and Extension Center in North Platte, NE, comparing two N application methods (IS and ES) and three N rates (128, 186, and 278 kg N per ha) using a randomized complete block design with four replications. No grain yield or biomass response was observed in 2004. In 2005 and 2006, corn grain yield and biomass production increased with increasing N rates, and the IS treatment increased grain yield, total N uptake, and gross return after N application costs (GRN) compared to the ES treatment. Chlorophyll meter readings taken at the R3 corn growth stage in 2006 showed that less N was supplied to the plant with ES compared to the IS treatment. At the end of the study soil NO3-N masses in the 0.9 to 1.8 m depth were greater under the IS treatment compared to the ES treatment. Results suggested that greater losses of NO3-N below the root zone under the ES treatment may have had a negative effect on corn production. Under SDI systems, fertigating a recommended N rate at various corn growth stages can increase yields, GRN, and reduce NO3-N leaching in soils compared to concentrated early-season applications.