Agronomy and Horticulture Department

 

First Advisor

John Guretzky

Second Advisor

Walter Schacht

Date of this Version

Spring 5-2019

Citation

La Vallie, M.N. (2019). Establishment of Perennial Legumes with an Annual Warm-Season Grass as a Companion Crop (Master's Thesis). The University of Nebraska-Lincoln, Lincoln, Nebraska.

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 John A. Guretzky And Professor Walter H. Schacht. Lincoln, Nebraska: May, 2019

Copyright 2019 Martina N. La Vallie

Abstract

The yields of perennial forage legumes are often hindered during the establishment year due to slow germination rates and weed competition. This study was conducted to determine if sorghum-sudangrass (Sorghum bicolor x S. bicolor var. sudanese) is a compatible annual companion crop for increased forage production, weed suppression, and legume establishment. In 2016, sorghum-sudangrass was paired with alfalfa (Medicago sativa L. ‘Ranger’), birdsfoot trefoil (Lotus corniculatus L.), Illinois bundleflower [Desmanthus illinoensis (Michx.) MacMill. ex B.L. Rob. & Fernald], purple prairie clover (Dalea purpurea Vent.), red clover (Trifolium pratense L.), and roundhead lespedeza (Lespedeza capitata Michx.). We studied effects of a sorghum-sudangrass companion crop with a varying number of harvests (three vs. four harvests) collected per plot throughout the summer and compared yields to the yield of a weeded legume treatment, and a non-weeded legume treatment. In 2017, we studied effects of the application of four seeding rates for sorghum-sudangrass at 5 pure live seed per m2 (PLS/m2), 10 PLS/m2, 20 PLS/m2, and 40 PLS/m2 paired with only the alfalfa perennial legume and compared yields to the yield of an oat-alfalfa control treatment, a weeded alfalfa treatment, and a non-weeded alfalfa treatment. Total dry matter yields along with the yield of each legume, weeds, sorghum-sudangrass, and oats (second year only) were collected for each treatment. In both years, we found the addition of sorghum-sudangrass increased overall dry matter yield and significantly decreased weed abundance. The increase in total dry matter yield came at a cost to the legume yield; as treatments planted with sorghum-sudangrass or oats had lower legume/alfalfa yields than weeded legume/alfalfa treatments. These results suggest that sorghum-sudangrass is a viable option for weed suppression but is not ideal as a companion crop with an establishing legume stand for weed control as it decreases the success of legume establishment. These results demonstrate the importance of selecting a companion crop that is compatible with the crop of interest to achieve production goals.

Advisors: John Guretzky and Walter Schacht

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