Effects of nitrogen rates and tillage treatments on irrigated corn yields and nitrogen budgets, cycling, and use efficiencies

Authors: Delgado, Jorge; HALVORSON, ARDELL - Retired ARS Employee; VILLACIS, ALEXIS - Arizona State University; Stewart, Catherine; D Adamo, Robert; Del Grosso, Stephen - Steve; Manter, Daniel; Floyd, Bradley; ALWANG, JEFFREY - Virginia Polytechnic Institution & State University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/16/2021
Publication Date: N/A
Citation: N/A

Interpretive Summary: Abstract only

Technical Abstract: Management factors such as nitrogen fertilizer rates and tillage intensity could affect grain yields and nitrogen cycling, uptake, budgets, and use efficiencies in cropping systems such as corn, the most nitrogen-fertilized crop in the United States. Our presentation will cover results from two studies that are currently being prepared for submission to peer review. Long-term nitrogen and tillage studies were conducted at the Halvorson plots located at the Colorado State University Agricultural Research, Development and Education Center (CSU-ARDEC) in Fort Collins, Colorado. One study covers the effects of several nitrogen rates on aboveground biomass, grain yields, and nitrogen uptake, budgets, and use efficiencies of irrigated no-till (NT), conventional till (CT), and strip-till (ST) corn. The other study conducts a detailed nitrogen mass balance of the no-till system, monitoring soil nitrogen pools and plant compartments. Our results suggest greater nitrogen cycling in the conventional tillage plots than the no-till plots. The nitrogen rates to maximize yield and nitrogen uptake will be presented as well as maximum yields and biomass production for these irrigated corn systems. The detailed nitrogen balance conducted for the no-till plots suggests that no-till contributes to an accumulation of total N in the soil system and that carbon is also accumulating in the top 7 cm. The system is losing organic carbon in the baseline soil depth of 120 cm. However, the data suggest that fertilizer under no tillage contributes to reduced losses of C from the system. In the no-till plots with high rates of fertilizer application, inorganic nitrogen is accumulating and moving to the lower depths. The data also suggest that although nitrogen inputs increase the losses of this nutrient to the environment, there is significant deposition of nitrogen into this irrigated corn system and the absence of inorganic nitrogen fertilizer application for nearly two decades has not reduced the yields of the control plots, which are about 48% lower than the yields of the fertilized plots. A detailed discussion of the effects of tillage on yields and nitrogen use efficiencies will be presented in conjunction with a nitrogen balance for the no-till system and a discussion of potential pathways for losses and inputs into these irrigated corn systems.