Control of Weeds in Narrow‐Row Soybeans¹

Abstract

Improved weed control systems in the absence of row cultivation were researched in order to take advantage of higher yields of soybeans [Glycine max (L.) Merr.] grown in narrow rows. Weed control systems, utilizing 13 pre‐emergence and two postemergence herbicides or herbicide combinations and the rotary hoe, were devised for the production of narrow‐row soybeans at two locations in eastern Nebraska during 1972–74. Experiments were conducted on a Sharpsburg silty clay loam (Typic Argiudoll) at Lincoln and on a Judson clay loam (Cumulic Hapludoll) at Concord, Neb. Research was undertaken to reduce labor, energy, and production costs while attempting to achieve better weed control, earlier ground cover, and higher soybean yields. Selective control of grass weeds in soybeans was more readily accomplished than the control of such large‐seeded broadleaf weeds as Pennsylvania smartweed (Polygonum pensylvanicum L.), sunflower (Helianthus annuus L.), and valvetleaf (Abutilon theophrasti Medic.). Reduced application rates of grass herbicides were used successfully in narrow‐row soybeans. Weeds were controlled in soybeans, with a number of herbicide treatments, with only minor early crop injury and no stand reduction. Average weed yields from all herbicide treatments were markedly lower than those on weedy check plots, but were not significantly different from the hand‐weeded plots. All herbicide treatments except one produced average soybean yields that were equivalent to those on the hand‐weeded plots. Available weed control systems can eliminate the need for cultivation in narrow‐row soybean production. Such systems of weed control should increase soybean yields, reduce production costs, require less labor and fuel, and improve ground cover needed to protect our soil from wind and water erosion.

High Planting Rates Improve Weed Suppression, Yield, and Profitability in Organically-Managed, No-till–Planted Soybean

“…Congruent with previous research showing that weed interference in soybean reduces the number of pods per plant and negatively impacts other yield components (Burnside and Moomaw 1977; Harris and Ritter 1987; Knake and Slife 1969; Krausz et al 2001; Monks and Oliver 1988; Young et al 1982), soybean yield decreased as weed biomass increased in our experiment (Figure 4). However, we cannot completely separate the effects of increasing weed biomass and decreasing soybean density on soybean yield.…”

Identifying Soybean Traits of Interest for Weed Competition

“…If larger seeds experienced a germination delay this may have ultimately resulted in reduced soybean stand density. Investigations of soybean seeding rate effects on weed competition show that a reduced stand density would be a disadvantage for ability to compete with weeds (Burnside and Moomaw, 1977; Légère and Schreiber, 1989; Nice et al, 2001, Place et al, 2009). Such a reduced stand count disadvantage may suggest a slight competitive ability trade off with the larger seed size that could be offset by a higher seeding rate.…”

Effect of Soybean Row Width and Population on Weeds, Crop Yield, and Economic Return

“…However, advances in herbicides and equipment have allowed growers to plant soybean in narrow rows and rely on herbicides to control weeds. Weed control is generally improved in narrow compared with wide rows due to more rapid canopy closure (Burnside and Moomaw 1977;Chandler et al 2001;Dalley et al 2004a; Légère and Schreiber 1989;Mickelson and Renner 1997;Mulugeta and Boerboom 2000;Nelson and Renner 1999;Nice et al 2001;Young et al 2001).…”