Advancing A Tool For Cover Crop And Soil Organic Matter Adjusted Nitrogen Fertilizer Recommendations In Agronomic And Horticultural Production Systems
Open Access
- Author:
- Colin, Anthony
- Graduate Program:
- Agronomy
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- October 05, 2021
- Committee Members:
- Charlie White, Thesis Advisor/Co-Advisor
Curtis Dell, Committee Member
Erin Connolly, Program Head/Chair
Heather D Karsten, Thesis Advisor/Co-Advisor - Keywords:
- cover crop
nitrogen
adaptive N management
corn
maize
cabbage
winter cover crop
fertilizer
mineralization
immobilization
manure - Abstract:
- Increased knowledge of the environmental and economic drawbacks to intense nitrogen (N) fertilizer usage has led to the development of better theoretical frameworks and cropping practices. The cover crop (CC) is one such practice that, in addition to tertiary benefits like building soil organic matter (SOM), promises utility in scavenging fertilizer N applied in excess, and fixing atmospheric N2 into crop-available N. The extent to which this CC-N becomes more or less available to a following crop during SOM-mediated N cycling can be predicted through the use of a decision support tool previously developed in corn grain and silage. In addition to testing the predictions and increasing the practical usability of this tool, our first study aims to evaluate its novel SOM- and CC-N adjusted fertilizer recommendation equation in a range of corn cropping systems common to the U.S. In comparing the yields and N-status of this tool’s recommendation to regional yield-based and adaptive N recommendation systems, the Penn State Agronomy Guide and Pre-Sidedress Nitrate Test, we found that the N supply tool under-yielded in all but one cropping context. However, the results of N Status along with ancillary evaluations of the tool’s performance and internal parameters revealed both promising avenues for further development of such vital decision support tools, and a habitual overapplication of N by other systems that underlines the need for such tools. A second study utilized developments in horticultural systems N management to adapt and test our tool for white cabbage production. Although yields were limited by multiple factors, including our most optimistic N supply tool recommendation rate, our exploration of N utilization efficiency in this system once again yielded promising avenues for the continued development of such tools in horticultural production systems.