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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Agricultural Systems Research » Research » Publications at this Location » Publication #204990
Title: Preplant weed management and planting date influence yield, water use, and weed seed production in herbicide-free forage barley

Author
item Lenssen, Andrew

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/11/2008
Publication Date: 9/22/2008
Citation: Lenssen, A.W. 2008. Preplant weed management and planting date influence yield, water use, and weed seed production in herbicide-free forage barley. Weed Technology. 22:489-492.

Interpretive Summary: In semiarid regions, the adoption of zero tillage improves soil water conservation, allowing for increased crop intensification and diversification. Zero tillage crop production relies heavily on herbicides for weed management, particularly the herbicide glyphosate, increasing selection pressure for herbicide-resistant weeds. Barley is well adapted to the northern Great Plains, and may be a suitable herbicide-free forage crop in zero tillage systems. A field study was conducted to determine if planting date influenced crop and weed biomass, water use (WU), water use efficiency (WUE), and weed seed production of barley in three preplant weed management systems, 1) conventional preplant tillage with a field cultivator (TILL), 2) zero tillage with preemergence glyphosate application (ZTPRE), and 3) zero tillage without preemergence glyphosate (ZT). None of the systems included an in-crop herbicide. Planting dates were mid-April (early), late May (mid), and mid-June (delayed). Early planting of ZT barley resulted in excellent forage yields (4.0 tons/acre), similar to those from TILL and ZTPRE. Early planting resulted in a small accumulation of weed biomass, averaging 71 lbs/acre, and no weed seed production regardless of preplant weed management system. Early planting resulted in higher WU than delayed planting, averaging 11.4 and 8.7 acre/inches, respectively, across management systems and years. The WUE of crop and total biomass did not differ among preplant weed management systems at harvest from the early planting date. Delayed planting resulted in decreased forage yield with high amounts of weed biomass and seed production, especially in ZT. A preemergence glyphosate application was not necessary for early planted ZT forage barley. Early planting herbicide-free barley for forage can be an excellent addition to northern Great Plains cropping systems as part of a multi-tactic approach for improved weed and water management.

Technical Abstract: In semiarid regions, the adoption of zero tillage improves soil water conservation, allowing for increased crop intensification and diversification. Zero tillage crop production relies heavily on herbicides for weed management, particularly the herbicide glyphosate, increasing selection pressure for herbicide-resistant weeds. Barley is well adapted to the northern Great Plains, and may be a suitable herbicide-free forage crop in zero tillage systems. A field study was conducted to determine if planting date influenced crop and weed biomass, water use (WU), water use efficiency (WUE), and weed seed production of barley in three preplant weed management systems, 1) conventional preplant tillage with a field cultivator (TILL), 2) zero tillage with preemergence glyphosate application (ZTPRE), and 3) zero tillage without preemergence glyphosate (ZT). None of the systems included an in-crop herbicide. Planting dates were mid-April (early), late May (mid), and mid-June (delayed). Early planting of ZT barley resulted in excellent forage yields (7.2 Mg ha-1), similar to those from TILL and ZTPRE. Early planting resulted in a small accumulation of weed biomass, averaging 0.08 Mg ha-1, and no weed seed production regardless of preplant weed management system. Early planting resulted in higher WU than delayed planting, averaging 289 and 221 mm, respectively, across management systems and years. The WUE of crop and total biomass did not differ among preplant weed management systems at harvest from the early planting date. Delayed planting resulted in decreased forage yield with high amounts of weed biomass and seed production, especially in ZT. A preemergence glyphosate application was not necessary for early planted ZT forage barley. Early planting herbicide-free barley for forage can be an excellent addition to northern Great Plains cropping systems as part of a multi-tactic approach for improved weed and water management.