Influence of tillage and crop residue on postdispersal predation of weed seeds

Abstract

Field experiments were conducted from 1995 to 1997 in southern Ontario to determine the influence of tillage and ground cover on the quantity of postdispersal seed predation of common lambsquarters and barnyardgrass. Ground-dwelling invertebrates were the dominant seed predators and were responsible for 80 to 90% of all seeds consumed. Predation was highest in no-till and moldboard-plowed environments (averaging 32% in both) and lowest in chisel-plowed environments (averaging 24%). This indicates that the relationship between the level of disturbance and predation is nonlinear and that other factors, such as the mobility of invertebrates and food availability, may also play important roles in determining the quantity of seed predation. In no-till, the type of crop residue also influenced the quantity of predation, with highest seed predation found in plots with corn residue (averaging 31%) and lowest in those with soybean and wheat residue (24 and 21%, respectively). It is apparent that there is an optimum combination of residue quantity and quality that maximizes the quantity of seed predation. Based on the experimental design used in this study, no feeding preference by seed predators was detected between common lambsquarters and barnyardgrass. Density-dependent feeding, however, was evident for both species. Most biological control efforts have centered around predators with specific feeding habits. We contend that invertebrates with opportunistic feeding strategies that feed on weed seeds may be the most significant broad spectrum and natural form of biological weed control affecting weed population dynamics. Populations of beneficial arthropods should be conserved, and management strategies that augment the size of their natural populations should be encouraged.

Weed dynamics and conservation agriculture principles: A review

“…Other studies have found no difference (Cardina et al, 1996;Cromar et al, 1999), but both of these studies were conducted in plots less than 0.3 ha in size which may not have been large enough to detect differences due to the mobility of predators . The reported increases in numbers of predators may be due to both increased habitat (Díaz, 1991;Kromp, 1999;Cunningham et al, 2004;Baraibar et al, 2009) or decreased tillage-induced mortality (Thorbek and Bilde, 2004;Shearin et al, 2007).…”

“…Studies have shown residue effects on predation rates depend on the type of residue, surrounding landscapes, and the type of native predator populations (Bommarco, 1998;Cromar et al, 1999;Liebman, 2001). Some studies report extended season ground cover is correlated with increased predation (Gallandt et al, 2005;Heggenstaller et al, 2006) while others have found no effect (Harrison et al, 2003;Jacob et al, 2006;Chauhan et al, 2010).…”

Precise tillage systems for enhanced non-chemical weed management

“…Although the no-till type seems best suited to expose weed seeds at the soil surface and sustain predator populations (Brust and House, 1988;Harrison et al, 2003), Cardina et al (1996) and Cromar et al (1999) did not find different predation rates in mouldboardploughed and no-till crop fields. Mice, beetles and birds may consume large amounts of weed seeds, but the amounts vary with species, time and space (Lutman et al, 2002;Harrison et al, 2003;Westerman et al, 2003).…”

Weed Problems, Ecology, and Management Options in Conservation Agriculture: Issues and Perspectives

“…The predation might occur either pre-dispersal while the seeds were still attached with the weed plants or post dispersal ("choke point" period in the weed life cycle), a form of biological means of keeping weeds under check could contribute significantly to weed population regulation (Ward et al, 2011) under NT. Nonlinear relationship between the level of disturbance and predation was observed and the predation of common lambsquarters and barnyardgrass was highest in NT (32%) at southern Ontario. Predation inclination of crop residues in NT viz., corn residue, soybean, and wheat were akin to the other (Cromar et al, 1999). Baraibar et al (2009) also found that NT increased seed predation in cereal production.…”

“…Ground-dwelling invertebrates (Shearin et al, 2007) were the dominant seed predators and were responsible for 80-90% of common lambsquarters and barnyardgrass seeds consumed at southern Ontario (Cromar et al, 1999) and these beetle banks contribute to conservation of biodiversity in agroecosystems (MacLeod et al, 2004). Bohan et al (2011) have found that carabids can elicit regulatory effects on moncotyledon and total weed seedbanks from fields undergoing management by farmers.…”