Weed Seedbanks of the U.S. Corn Belt: Magnitude, Variation, Emergence, and Application

Abstract

Seedbanks and seedling emergence of annual weeds were examined in arable fields at eight locations in the Corn Belt. Seed densities were estimated by direct seed extraction from each of several soil cores in each sampled plot. Average total seedbank densities ranged from 600 to 162 000 viable seed m-2among locations. Coefficients of variation (CV) typically exceeded 50%. CV for seed densities of individual species usually exceeded 100%, indicating strongly aggregated distributions. CV were lower for species with dense seed populations than those with sparse seed populations. Variance of total seedbank densities was unstable when < 10 cores were examined per plot, but stabilized at all locations when ≥ 15 cores were analyzed, despite a 12-fold difference in plot size and 270-fold difference in seed density among locations. Percentage viable seed that emerged as seedlings in field plots ranged from < 1% for yellow rocket to 30% for giant foxtail. Redroot pigweed and common lambsquarters were the most frequently encountered species. Emergence percentages of these species were related inversely to rainfall or air temperatures in April or May, presumably because anoxia and/or high temperatures induced secondary dormancy in nondormant seed. From 50 to 90% of total seed in the seedbank were dead. This information can be employed by bioeconomic weed management models, which currently use coarse estimates of emergence percentages to customize recommendations for weed control.

Effect of Weed Emergence Time and Intervals of Weed and Crop Competition on Potato Yield

“…Forcella et al (2000) reported that soil temperature, soil water, soil quality, and light quality are the main environmental factors affecting seed germination and seedling emergence in arable soils. The variation in timing of emergence depends on cultural practices and location (Forcella et al 1992).…”

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

“…Seed size also determines the extent of density-dependent predation and the exploitation of buried seed. Dormancy (Forcella et al, 1992) is a common attribute of many weed seed populations and tillage can modify it by exposing seeds to short pulses of light needed as germination triggers (Milberg et al, 1996) as the interaction between soil thermal and hydric conditions decide its modification , which might be a factor in CT. It hampers the task of predicting timing and extent of emergence of weeds under NT (Batlla and BenechArnold, 2007).…”

“…Knowledge of seedling emergence is critical for improving weed management strategies (Buhler et al, 1996;Forcella et al, 1992Forcella et al, , 2000Myers et al, 2004). This includes determining the effect of tillage and crop canopy formation on seedling emergence (Jha and Norsworthy, 2009).…”

Weed Seed Bank Dynamics

“…These seeds result in new plants that may reduce crop yields if not controlled. Sporadic germination in time and space (Forcella et al, 1992(Forcella et al, , 1996b) is a characteristic allowing weeds to survive despite our efforts to eradicate them. Dormancy is a primary mechanism regulating these variable germination patterns.…”

“…For coinmon annual species in cultivated soil, approximately 1 to 40% of the seed bank will emerge in a given year (Roberts and Ricketts, 1979;Forcella et al, 1992Forcella et al, , 1996bWilson and Lawson, 1992) with great variation both within and among weed species. The most cotmionly reported range of emergence under agronomic conditions is 3 to 6%.…”