Agronomy and Horticulture, Department of

 

First Advisor

Humberto Blanco

Date of this Version

5-2021

Comments

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, 2021

Copyright 2021 Lindsey Anderson

Abstract

Re-integrating crop and livestock production through cover crop (CC) and corn residue grazing could efficiently utilize resources and ensure profitability while improving environmental quality, but how this integration affects soils and crops is not well understood. We conducted two studies to address this. In the first study, we evaluated the impact of cattle (1.3-3.7 head ha-1) grazing an oat (Avena sativa L.) CC on soil and crop yields in two adjacent irrigated no-till corn (Zea mays L.)-soybean (Glycine max L.) fields on silt loam soils in eastern Nebraska. Field I was grazed twice, while Field II was grazed thrice during a 5-yr study. Cover crop grazing reduced CC biomass by 47 to 87% without impacting soil penetration resistance, bulk density, aggregate stability, hydraulic properties, organic matter fractions, microbial biomass, and crop yields compared to non-grazed CC. In the second study, we evaluated the impact of cattle grazing of corn residue [717-807 animal unit days (AUD) ha-1] and an oat CC (1354 AUD ha-1) on soil compaction parameters including bulk density, penetration resistance, and initial infiltration under two rainfed no-till systems (I and II) on a silty clay loam in eastern Nebraska. System I had one year of corn residue grazing under soybean-corn without horse manure, while System II had one year of CC grazing and another year of corn residue grazing under soybean-wheat (Triticum aestivum L)-corn with horse manure. Dry horse manure application rate in System II averaged 3.92 Mg ha-1. Oat CC was planted following wheat. Corn residue grazing did not impact bulk density, penetration resistance, and infiltration in both Systems. Cover crop grazing in System II did not impact penetration resistance and infiltration but increased bulk density (1.43±0.04 vs 1.38±0.04 Mg m-3), although the increase was below values that affect root growth. Overall, grazing of CC and corn residue has little to no impact on soil properties and crop production and, thus, it could be a viable practice to re-integrate crop with livestock production.

Advisor: Humberto Blanco

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