Improving publicly available corn nitrogen rate recommendation tools with soil and weather measurements. (17th March 2021)

• Record Type: Journal Article
• Authors: Ransom, Curtis J.; Kitchen, Newell R.; Sawyer, John E.; Camberato, James J.; Carter, Paul R.; Ferguson, Richard B.; Fernández, Fabián G.; Franzen, David W.; Laboski, Carrie A. M.; Myers, D. Brenton; Nafziger, Emerson D.; Shanahan, John F.
• Is Part Of: Agronomy Journal. Volume 113:Number 2(2021)
• Page Start: 2068
• Page End: 2090
• Publication Date: 2021-03-17
• Subjects: Agronomy -- Periodicals; 630
• DOI: 10.1002/agj2.20627
• Languages: English
• ISSNs: 0002-1962

Abstract

Abstract: Improving corn ( Zea mays L.) N fertilizer rate recommendation tools is necessary for improving farmers' profits and minimizing N pollution. Research has repeatedly shown that weather and soil factors influence available N and crop N need. Adjusting available corn N recommendation tools with soil and weather measurements could improve farmers' ability to manage N. The aim of this research was to improve publicly available N recommendation tools with site‐specific soil and weather measurements. Information from 49 site‐years of N response trials in the U.S. Midwest was used to evaluate 21 rate recommendation tools for a single (at‐planting) and split (at‐planting + sidedress) N application. Using elastic net and decision tree algorithms, the difference between each tool's N recommendation and the economically optimum nitrogen rate (EONR) was modeled against soil and weather measurements. The model's predicted values were used to adjust the tools. Unadjusted the best performing tool had r 2 = .24; after adjustment, the best performing tool had r 2 = .57. Overall tool improvement was modest and sometimes required many additional inputs. Using weather measurements (e.g., evenness of rainfall or abundant and well‐distributed rainfall) helped increase N recommendations by accounting for N loss while soil measurements (e.g., pH and total C) helped decrease N recommendations when there was sufficient available soil N. This investigation showed that incorporating soil and weather measurements is a viable approach for improving corn N recommendation tools regionally; but even with adjustments, tools still have room for additional improvement. Core Ideas: Tested two methods for improving 21 different corn N recommendation tools. Majority of tools improved by incorporating weather and soil measurements. Best unadjusted tool had an r 2 = .24, with adjustments best tool had r 2 = .57.