Nitrogen Recalibration for Corn in North Dakota

The nitrogen (N) recommendations for corn in North Dakota (ND) need to be updated using actual field results from ND. Existing recommendations are based on Minnesota data, and older ND field calibration data. There have been many changes in cropping systems especially conservation tillage adoption, weed control, and corn hybrid genetics. Many of the newer hybrids are more resistant to water limiting conditions experienced in parts of ND. The study will consist of N response research experiments at a number (8 to 10) of sites depending on resources and locating suitable field research sites. This study will be conducted for two years to generate data for up to 20 site-years of research results.


16 Apr 2014

2013 Annual Interpretive Summary

This was the final year of a three-year project initiated in 2010 with the objectives to a) build a data base of N application rate trials across important corn-producing regions of North Dakota with the goal of improving N fertilizer rate recommendations for corn growers, and b) develop algorithms with active optical sensors with the purpose of directing in-season N application rates for corn. Each research site had six N fertilizer application rates (0, 40, 80, 120, 160, and 200 lb N/A) with four replications. In the individual plot to which treatments were imposed, measurements taken and harvest was made from subplots (10 feet wide and 20 feet long). At the end of 2013, there have been 77 harvested locations. Crop measurements were made with the Greenseeker (Trimble) and the Holland Scientific Crop Circle sensors at the V6 leaf stage at all the eastern sites and in the western sites only in 2013. Corn yield was compared with total known available N (i.e., residual nitrate before planting + previous crop credit+ added N fertilizer). An economic production function is being imposed with the data to determine the economic N rate.

The field work for constructing the data set has been completed. Additional site-years of recent N rate trials from southern Manitoba, northwest Minnesota and northern South Dakota have been added to the data set for a total of 117 site-years. The statistical relationship between N application rate and corn yield improved greatly by including soil nitrate concentrations to a 2 ft. depth. There will be a separate rate structure based on the MRTN model for west-river, eastern high-clay soils, eastern medium-texture soils, and eastern long-term no-till soils. Active-optical sensor algorithms for all areas are currently being developed to help direct in-season N fertilizer application. The new N fertilizer rate recommendations and the algorithms will be available in the summer of 2014.