Effects of Tillage on Vertical Distribution and Viability of Weed Seed in Soil

Abstract

The effect of different levels of tillage and weed management on population, distribution, and germination of weed seed was evaluated in three tillage systems at Arlington and Hancock, WI, in 1989 and 1990. Over 60% of all weed seed in the top 19 cm of soil were found in the top 1 cm in no-tillage at both sites. As depth increased, concentration of weed seed declined logarithmically in no-tillage. In chisel plowing, over 30% of seed were in the top 1 cm and seed concentration decreased linearly with depth. Moldboard plowing had uniform distribution of weed seed in the top 19 cm of soil. Preemergence metolachlor plus atrazine decreased weed seed population by 50% compared with no treatment over all tillage systems. One year of the herbicide treatment plus handweeding to assure weed-free conditions did not reduce seed numbers in chisel plowing or moldboard plowing compared to herbicide alone. Seed numbers with no-tillage and weed-free conditions decreased by 40% relative to herbicide alone. Common lambsquarters germination was 40% greater in moldboard plowing and chisel plowing compared with no-tillage. Germination was highest in seed taken from 9 to 19 cm deep in moldboard plowing and from 0 to 9 cm deep in chisel plowing.

Weed spectrum in different wheat-based cropping systems under conservation and conventional tillage practices in Punjab, Pakistan

“…Indeed, tillage changes the horizontal and vertical distribution of weed seeds in the soil (Yenish et al, 1992;Buhler et al, 1997;Chauhan et al, 2006) and determines weed emergence and species composition (Buhler, 1997;Sosnoskie et al, 2006;Murphy et al, 2006). In this study, weed density in ZT was higher (Tables 3-6) owing to a higher abundance of weed seeds in the upper soil layer (Dessaint et al, 1997;Feldman et al, 1997;Barberi and Lo Cascio 2001;Torresen et al, 2003).…”

Alternative Strategies for Transitioning to Organic Production in Direct-Seeded Grain Systems in Eastern Washington I: Crop Agronomy

“…Maxwell et al (2007) suggest, however, that some weed escapes may be tolerable in organic systems, since densitydependent mortality events, such as seed predation and decay, will help slow weed proliferation. In our reduced tillage system, weed seed burial is likely to be considerably less than what would occur under conventional and other reduced tillage systems (i.e., chisel plow) (Yenish et al, 1992), thereby leaving the seeds more prone to predation (Cromar et al, 1999;Menalled et al, 2007). Clearly, successful weed management in organic dryland wheat systems will require the integration of well targeted mechanical control strategies with cultural measures such as enhanced crop competition and enhanced biological mortality factors.…”

Weed dynamics and conservation agriculture principles: A review

“…The effect of tillage on the distribution of seeds in the soil profile is simpler than the effect on seed bank size; regardless of soil type, tillage redistributes seeds throughout the soil profile. In NT soils, seeds infiltrate the soil via very slow processes (cracks, fauna, freeze-dry cycles), resulting in an accumulation of weed seeds (60-90%) in the top 5 cm of the soil (Yenish et al, 1992;Hoffman et al, 1998;Bàrberi et al, 2001). Common tillage regimes have generalized patterns of seed distributions (Ball, 1992;Mohler, 1993;Dorado et al, 1999;Fig.…”