Comparison of Fallow Tillage Methods in the Intermediate Rainfall Inland Pacific Northwest

Abstract

Winter wheat (Triticum aestivum L.) is usually grown in the Pacific Northwest (PNW) intermediate rainfall zone following tilled or chemical summer fallow. Studies were conducted near Davenport, WA and Helix, OR over two fallow–winter wheat cycles to evaluate the efficacy of reduced or no‐tillage fallow compared to conventional fallow and compare the efficacy of herbicides applied using a light‐activated sensor‐controlled (LASC) applicator to broadcast applications. Six treatments included conventional primary tillage followed by rodweeding; sweep‐tillage followed by rodweeding, broadcast, or LASC herbicide application; and no‐tillage followed by broadcast or LASC herbicide application. Broadcast and LASC herbicide applications controlled weeds similarly in no‐tillage treatments. However, LASC applications used from 45 to 70% less herbicide than broadcast applications to attain similar weed control. No‐tillage or sweep‐tillage systems with herbicide application had from 15 to 30% greater surface residue cover than the conventional tillage system. Available soil moisture in both the root‐zone and seed‐zone soil profiles at time of planting was similar among tillage systems. There were no differences in wheat quality parameters across treatments. The conventional tillage system had similar wheat grain yield as sweep‐tillage systems followed by rodweed or broadcast herbicide application, but yields were up to 21% greater than sweep‐tillage with LASC applied herbicides and no‐tillage systems. Reduced tillage systems using sweep‐tillage and broadcast herbicide application could potentially replace more tillage intensive fallow systems in the PNW.

Yield, water productivity and economic return of dryland wheat in the Loess Plateau in response to conservation tillage practices

“…Additionally, no statistical differences in grain yield were detected in the first 2 years, because the effect of tillage on grain production might require a long period of time (>2 year) before it can be detected (Halvorson et al 2002). Previous studies also suggested that traditional winter wheat cropping systems (winter wheat followed by summer fallow using conventional tillage) could be replaced by no-till or sweep-tillage practices followed by herbicide application, which should provide increased WP and comparable grain yield (Riar et al 2010; Machado et al 2015). The current results indicated that conservation tillage practices consistently provided comparable or lower yield than conventional tillage practices, as NT and NTS treatments had lower yield than T, a result that is quite different from many studies conducted in the dryland areas of North China (He et al 2007 a ; Su et al 2007; Zhang et al 2013; Shao et al 2016).…”

The influence of soil tillage system on Salsola kali L. emergence during the fallow period within cereal fields

“…These seeds then enter the soil seed bank and can even germinate earlier than crops depending on environmental conditions (Cardina, Herms, Doohan, Cardina, & Doohan, 2002; Schillinger, 2016). Out of control weeds will negatively affect the soil water and nitrogen content counteracting the effects of leaving the soil to fallow (Riar, Ball, Yenish, Wuest, & Corp, 2010).…”

“…It is agreed that the physical disturbance of the soil caused by the tillage and residue management are crucial factors in the determination of the diversity of weed species in the agro‐ecosystem (Sosnoskie, Herms, & Cardina, 2006; Tuesca, Puricelli, & Papa, 2001). Soil tillage techniques (Aboudrare, Debaeke, Bouaziz, & Chekli, 2006; Riar et al., 2010), as weed control methods (Blackshaw, Larney, Lindwall, Watson, & Derksen, 2001; Rahman, 2017; Streit, Rieger, Stamp, & Richner, 2003; Tørresen & Skuterud, 2002), are of particular importance during the fallow period because more than 95% of seeds entering the seed bank in arable land come from annual weeds growing on the same land (Albrecht, 2005; Ekeleme, Akobundu, Isichei, & Chikoye, 2000). If we do not control weeds at the fallow stage, we need to rely on herbicides, and it will increase the probability of herbicide‐resistant and hard‐to‐kill weeds (Chauhan et al., 2012).…”

Scouringrush (Equisetum spp.) control in dryland winter wheat

“…When tillage is removed from the system, weeds are managed through a chemical fallow strategy that has successive selective and nonselective herbicide applications replace conventional tillage (Jemmett et al 2008;Wicks and Smika 1973). Fall-planted crops are then direct seeded into previous crop residue, omitting preplant tillage (Riar et al 2010). Where chemical fallow has been integrated as the standard practice, a weed species composition shift has taken place in which scouringrush and a sterile hybrid, intermediate scouringrush have invaded production fields.…”