Document Type

Dissertation - Open Access

Award Date

2016

Degree Name

Doctor of Philosophy (PhD)

Department / School

Plant Science

First Advisor

Sharon A. Clay

Keywords

corncob, cultivation, flaming, grit, organic

Abstract

Weed management is one of the most challenging production problems in organic cropping systems because of limited weed control methods. Grits, derived from agricultural residues, have been demonstrated to control weed seedlings selectively in corn. This research examined weed efficacy and crop yield of an integrated air-propelled abrasive corncob grit (for in-row weed control) at varying timings and frequencies and flame-weeding or cultivation (for between-row weed control) system in two corn production systems. In the first study efficacy of weed control was assessed with this approach in an organic corn silage production system established in Morris, MN in 2013 and 2014. The second study examined efficacy of weed control with this method in a transitioning corn production system established in Aurora, SD in 2013 and 2014. A third study compared efficacy of weed control in both production systems. Measurements included: weed identification, weed density by species, weed biomass (total, broadleaf, grass, in-row, and between-row), plant height, and corn yield (silage and grain). Early applications of abrasive corncob grit resulted in the decrease of 68% and 52% of the total weed biomass in two years of evaluation, and it increased corn silage yield up 26 % when compared to the season long weed control. Late application of corncob grit at the V7 corn growth stage resulted in less weed control. One application at V1 increased corn yield. Additional treatments with or after the V1 treatment improved weed control and may increase yield. Waiting until V5 for grit application resulted in 80% in-row weed biomass reduction, however, there was no positive effect on corn yield. In the second study, in-row weed control resulted in the decrease of 61% of total weed biomass in the transitioning corn production system. Between-row weed control reduced total weed biomass up to 31% for cultivation and 51% for flaming. Even though the application of corncob grit as well as cultivation and flaming at the V5 corn growth stage reduced the total weed biomass, an application of these treatment-combinations at early stages of corn development may potentially achieve better weed control. A treatment combination of in-row weed control and between-row weed control reduced grass biomass. Between-row weed control treatments alone reduced grass weed biomass up to 68% and 61% with flaming treatments. Application of abrasive corncob grit increased corn yield up to 9% compared to the season long weed control. The comparison of these two systems determined that abrasive corncob grit for in-row weed control can reduce weed biomass in both weed control systems and increase silage and corn grain yield.

Library of Congress Subject Headings

Corn -- Weed control

Corn -- Organic farming

Corn -- Residues

Description

Includes bibliographical references (pages 135-149)

Format

application/pdf

Number of Pages

164

Publisher

South Dakota State University

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Included in

Weed Science Commons

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Rights Statement

In Copyright