Agronomy and Horticulture, Department of

 

First Advisor

Amit Jhala

Second Advisor

Humberto Blanco

Third Advisor

Stevan Knezevic

Date of this Version

Spring 5-4-2023

Citation

Stephens T (2023) Evaluating Planting Green and Herbicides for Integrated Weed Management and Their Effect on Soil Properties in Corn and Soybean in Nebraska. M. Sc thesis. Lincoln, NE: University of Nebraska-Lincoln. 143 p

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 Amit J. Jhala. Lincoln, Nebraska: May, 2023

Copyright © 2021 Trey Parker Stephens

Abstract

Producers across the Midwest are finding new ways to implement cover crops into cropping systems and the practice of “Planting Green” is one of the newest uses of cover crops. When planting green, producers plant their row crops into actively growing cover crops and terminate the cover crop at time of planting or shortly after planting. This practice would allow for higher biomass accumulation of the cover crop and could aid in weed management of herbicide-resistant weeds. The objective of the first two studies was to evaluate planting green and its effect on soil-applied residual herbicides, weed management, dicamba/glyphosate-resistant soybean yield, soil chemical and physical properties and economics in soybean. Treatments consisted of two different cover crop termination timings, three different herbicide application timings, and three different herbicides within each application and termination timing. All soil-applied herbicides controlled giant foxtail 79% to 99% in 2021 and 2022, and controlled Palmer amaranth 99% in 2021 and 53% to 73% in 2022. Thus, we can conclude that soil-applied herbicides are not affected by planting green. Pyroxasulfone/sulfentrazone fb dicamba and imazethapyr/saflufenacil/pyroxasulfone fb dicamba both consistently controlled Palmer amaranth above 90% in both years when paired with Planting Green in soybean. In 2021, soybean yields varied among termination timings and herbicide programs but PRE fb LPOST treatments provided the most consistent yields (3,324 kg ha-1 to 4,613 kg ha-1). In 2022 due to compounding weather factors, all planting green treatments yielded higher than earlier terminated treatments. The second study was conducted in corn and in 2022 PRE fb Late POST herbicide programs combined with Planting Green provided the highest amount of Palmer amaranth control at 28 days after Late POST application: 92% to 97% control. Treatments that contained glyphosate or a residual grass-killing herbicide were most effective on giant foxtail in corn and soybean. In 2021, all planting green treatments yielded lower than earlier terminated treatments in corn. In 2022, a starter fertilizer application was made, and yields were significantly higher than the year before and the highest yielding treatment was acetochlor/clopyralid/mesotrione fb dicamba/mesotrione with planting green at 14,189 kg ha-1.

Advisor: Amit. J Jhala

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