Influence of Tillage, Crop Rotation, and Weed Management on Giant Foxtail (Setaria faberi) Population Dynamics and Corn Yield

Abstract

A long-term integrated pest management study initiated in 1980 and continued through 1991 was conducted to determine interactions of tillage, crop rotation, and herbicide use levels on weed seed populations, weed populations, and crop yield. This paper presents giant foxtail seed population and stand along with corn yield in continuous corn, corn rotated with soybean, or corn following wheat in a soybean-wheat-corn rotation. Increasing herbicide use levels above the minimum reduced giant foxtail seed in the 0- to 2.5-cm depth of soil. Reducing tillage from conventional moldboard plowing to chiseling to no-tilling increased giant foxtail seed in only the top 0 to 2.5 cm of soil. No-tilling increased giant foxtail seed over conventional tillage in each year data were collected. Growing corn in a soybean-corn or soybean-wheat-corn rotation reduced giant foxtail seed from corn grown continuously in all three soil depths sampled: 0 to 2.5 cm, 2.5 to 10 cm, and 10 to 20 cm. Although stands of giant foxtail tended to follow soil weed seed counts, crop rotation significantly reduced giant foxtail stand with maximum reduction in the soybean-wheat-corn rotation in all tillage systems. Giant foxtail stands were reduced following wheat in no-tilling, probably because of the allelopathic influence of wheat straw. Corn yields showed weed management levels above minimum control are not justified regardless of tillage and crop rotation.

Weed dynamics and conservation agriculture principles: A review

“…Other studies show medium-disturbance tillage enhances control of certain weeds compared to NT + Res (Schreiber, 1992;Blackshaw, 1994;Cardina et al, 2002;Legere et al, 2011). Interestingly, of the studies showing more weeds in NT + Res compared to CT + Res, ones that report both yield and weed densities show that despite having more weeds, yields in rotated NT + Res are either equal to or higher than those in the rotated CT + Res systems (Schreiber, 1992;Legere et al, 2011). This may be because weed density may not be representative of weed biomass, which is more important when considering crop competition and yield reductions.…”

“…In a study done in the mid-western US, researchers compared the maize phase of a two-(maize-soybean) and three-year (maize-soybean-wheat) rotation (Schreiber, 1992). Although the weed seedbank size did not differ between the rotations, regardless of tillage the maize in the three-year rotation had had lower weed densities compared to the maize-soybean rotation, meaning less of the seedbank germinated.…”

“…Some studies show NT works synergistically with rotations to further reduce weed densities compared to tilled systems (Kegode et al, 1999;Anderson, 2005;Murphy et al, 2006). Other studies show medium-disturbance tillage enhances control of certain weeds compared to NT + Res (Schreiber, 1992;Blackshaw, 1994;Cardina et al, 2002;Legere et al, 2011). Interestingly, of the studies showing more weeds in NT + Res compared to CT + Res, ones that report both yield and weed densities show that despite having more weeds, yields in rotated NT + Res are either equal to or higher than those in the rotated CT + Res systems (Schreiber, 1992;Legere et al, 2011).…”

“…Yields notwithstanding, in all rotation-tillage interaction studies the treatment with the highest weed densities was a monoculture grown in NT + Res (Schreiber, 1992;Blackshaw, 1994;Anderson et al, 1998;Kegode et al, 1999;Blackshaw et al, 2001;Cardina et al, 2002;Sosnoskie et al, 2006). Utilizing crop rotation in NT + Res systems is crucial for weed control.…”

Weed Seed Bank Dynamics

“…Ridging the soil just before canopy closure stiinulated germination of weed seed. The resulting weed population roduced up to 1000 seeds/in2 in continuous Schreiber (1992) found that growing corn in a soybeadcorn or soybeadwheat (Piticurn aestivimz L.)/corn rotation greatly reduced giant foxtail seed in thc soil compared to corn grown continuously, regardless of herbicide use or tillage system. The effects of crop rotation and environmental conditions associated with years and locations were larger than tillage effects on weed species coinposition and abundance in two separate studies in Canada (Derksen et al, 1993;Thoinas and Frick, 1993 Ball (1992) reported that cropping sequence was the most dominant factor influencing species composition in weed seed banks.…”