Impact of the quality of organic amendments on size and composition of the weed seed bank

Abstract

Running head: Effect of fertilizer quality on weed seed bank

Weed community composition after 43 years of long-term fertilization in tropical rice–rice system

“…Manure has also reported as a potentially important source of weed seeds (Miyazawa et al, 2004) but reports on the subsequent weed infestation in fields vary from no or little impact (Menalled et al, 2005;De Cauwer et al, 2011) to significant increase (Miyazawa et al, 2004).…”

Weed seed decay in conventional and diversified cropping systems

“…The variability of S. faberi and A. theophrasti seed decay results in this study suggests that other factors, which were not measured, might be also involved in the seed decay process. Those factors may include: the effect of soil bacteria on the seed coat and embryo (Chee‐Sanford et al ., ), the presence of antimicrobial compounds on seeds that prevent microbial colonisation (Davis et al ., ), the C:N ratio in the soil (De Cauwer et al ., ), the existence of ‘safe‐sites’ in the soil that prevent the decay of certain seeds (Conn & Werdin‐Pfisterer, ), spatial heterogeneity and patchiness in microbial population distributions (Chee‐Sanford, ), the effect of the competition for light, water and N by the crop on nutrient composition of the weed seed (Cardina & Sparrow, ) and seed damage by insects and vertebrates (Kremer & Spencer, ; Schutte et al ., ). It is important, therefore, that future research on seed decay takes a broad view of the biological interactions that weed seeds, and the weed plant itself, encounter during weed life cycles.…”

“…Weed seed decay rates can vary substantially among crops and crop management systems (Chee‐Sanford et al ., ; Davis et al ., ). Beneficial effects of diversified cropping systems on soil physical and chemical characteristics, such as increased organic matter content, greater aggregate stability, higher water retention in drought conditions and slower nutrient release (Buyer & Kaufman, ; Chee‐Sanford et al ., ), can impact the soil microbial population distribution and community structure (De Cauwer et al ., ), potentially influencing the colonisation and decay of weed seeds by soil microorganisms. Several studies have addressed the potential of agricultural systems that are less dependent on external, non‐renewable resources to reduce the weed seedbank through enhanced weed seed decay or reduced seedling recruitment (Liebman & Davis, ; Ullrich et al ., ).…”

“…De Cauwer et al . (), on the other hand, determined that ambient seedbank density was lowest in plots amended with compost with a low C:N ratio, whereas Kremer and Li () associated higher proportions of weed‐inhibiting bacteria with cropping systems with soils containing high levels of organic matter.…”

“…Ullrich et al (2011) did not find a consistent system effect on weed seed decay when they compared conventional cropping systems to organic systems receiving greater amounts of organic amendments and exhibiting higher soil microbial biomass. De Cauwer et al (2011), on the other hand, determined that ambient seedbank density was lowest in plots amended with compost with a low C:N ratio, whereas Kremer and Li (2003) associated higher proportions of weed-inhibiting bacteria with cropping systems with soils containing high levels of organic matter.…”