Impact of nitrogen fertilizer timing on nitrate loss and crop production in northwest Iowa

Thumbnail Image
Waring, Emily Rose
Pederson, Carl
Major Professor
Committee Member
Journal Title
Journal ISSN
Volume Title
Sawyer, John
Contingent Worker Contingent Worker Contingent Worker Contingent Worker Contingent Worker
Research Projects
Organizational Units
Organizational Unit

The Department of Agronomy seeks to teach the study of the farm-field, its crops, and its science and management. It originally consisted of three sub-departments to do this: Soils, Farm-Crops, and Agricultural Engineering (which became its own department in 1907). Today, the department teaches crop sciences and breeding, soil sciences, meteorology, agroecology, and biotechnology.

The Department of Agronomy was formed in 1902. From 1917 to 1935 it was known as the Department of Farm Crops and Soils.

Dates of Existence

Historical Names

  • Department of Farm Crops and Soils (1917–1935)

Related Units

Organizational Unit
Agricultural and Biosystems Engineering

Since 1905, the Department of Agricultural Engineering, now the Department of Agricultural and Biosystems Engineering (ABE), has been a leader in providing engineering solutions to agricultural problems in the United States and the world. The department’s original mission was to mechanize agriculture. That mission has evolved to encompass a global view of the entire food production system–the wise management of natural resources in the production, processing, storage, handling, and use of food fiber and other biological products.

In 1905 Agricultural Engineering was recognized as a subdivision of the Department of Agronomy, and in 1907 it was recognized as a unique department. It was renamed the Department of Agricultural and Biosystems Engineering in 1990. The department merged with the Department of Industrial Education and Technology in 2004.

Dates of Existence

Historical Names

  • Department of Agricultural Engineering (1907–1990)

Related Units

Journal Issue
Is Version Of
AgronomyAgricultural and Biosystems Engineering
Nitrate in subsurface tile drainage from Midwestern USA corn (Zea mays L.)-soybean [Glycine max (L.) Merr] systems is detrimental to water quality at local and national scales. The objective of this replicated plot study in Northwest Iowa, 2015–2020, was to investigate the influence of nitrogen (N) fertilizer timing on crop production and NO3 load in subsurface (tile) drainage discharge. Four treatments applied to corn included fall anhydrous ammonia with a nitrification inhibitor (F), spring anhydrous ammonia (S), split-banded urea at planting and mid-vegetative growth (SS), and no N fertilizer (0N). Across crops and years, NO3-N concentration in subsurface drainage discharge was the same 11.7 mg L–1 for F and S applied anhydrous ammonia (AA). Concentration was statistically lower with SS urea (10 mg L–1) than F and S, and 0N was lower than SS at 8.3 mg L–1. Average annual NO3-N loads were not different between any treatments due to plot variability in drainage discharge. Corn responded to N application, with overall mean yield the same for F, S, and SS. There were no agronomic or water quality benefits for applying AA in the spring compared to fall, where the F included a nitrification inhibitor and was applied to cold soils. Split-applied urea had a small positive water quality impact but no crop yield enhancement. This study shows that there were improvements to NO3-N concentration in subsurface drainage discharge, but more nutrient reduction practices are needed than fertilizer N management alone to reduce nitrate load to surface water systems.
This is the peer-reviewed version of the following article: Waring, Emily Rose, John Sawyer, Carl Pederson, and Matt Helmers. Impact of nitrogen fertilizer timing on nitrate loss and crop production in northwest Iowa (2022), which has been published in final form at DOI: 10.1002/jeq2.20366. Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). Copyright 2022 American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. Posted with permission.