Agronomy and Horticulture, Department of

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research
First Advisor
Humberto Blanco
Committee Members
Haishun Yang, Jay Parsons, Chris Proctor
Date of this Version
5-2025
Document Type
Thesis
Citation
A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science
Major: Agronomy
Under the supervision of Professor Humberto Blanco
Lincoln, Nebraska, May 2025
Abstract
Sloping and sandy soils are highly susceptible to degradation. The health of these soils could be improved with cover crops (CCs). However, CC effectiveness in improving soil health mainly depends on CC biomass production, which is often low in temperate regions. The question is: how can we increase CC biomass production? Lengthening the CC growing window can be a potential strategy. This study assessed how 1) interseeded and terminated early (2-3 weeks before crop planting) CC, 2) interseeded and terminated late (at crop planting) CC, 3) drilled (after harvest) and terminated early CC, 4) drilled and terminated late CC, and 5) no CC affected CC biomass production, soil properties, and crop yields. The study was conducted in no-till corn-soybean systems in sandy and sloping sites in Nebraska for 4 yr. At the sloping site, drilled CC produced more biomass when terminated late (0.55 vs 0.18 Mg ha-1) than other CC treatments. At the sandy site, both interseeded and drilled CCs produced more biomass when terminated late (1.35 vs 0.27 Mg ha-1) than interseeded when terminated early across the 4 yr. Late-terminated (drilled and interseeded) CCs accumulated more N than the early-terminated CCs. Cover crop impact on soil properties (e.g., particulate organic matter, total C, wet aggregate stability) was small and inconsistent. Additionally, CCs had no effect on crop yields but generally reduced net income. Extending the CC growing window increased CC biomass production, but its soil, crop, and economic benefits were limited after 4 yr.
Advisor: Humberto Blanco
Included in
Agricultural Science Commons, Agriculture Commons, Agronomy and Crop Sciences Commons, Botany Commons, Horticulture Commons, Plant Biology Commons, Sustainability Commons
Comments
Copyright 2025, Noshin Ara Tunazzina. Used by permission