Weeds and the soil environment - Ecological Management of Agricultural Weeds - page 248

Figure 5.11 Number ofseedlings ofseven weed species that emerged through
various rates ofrye mulch in a field experiment conducted in New York,USA.
(After Mohler & Teasdale,1993.)
where MAI is mulch area index (i.e., mulch surface area per unit ground area)
and b is a fitted constant. The magnitude of the exponential parameter, b ,
depends on the plant species and type of mulch. Most of the differences in
weed emergence through the seven mulch materials investigated by Teasdale
& Mohler (2000) could be accounted for by the proportion of solid volume in
the mulch.That is, mulch materials with a high proportion of solid (e.g., bark
chips, maize stalks) were more suppressive for a given MAI than were mulch
materials with a low proportion of solid (e.g., oak leaves). This result may
relate to the diffusion of reflected light into the mulch mass since the fraction
of volume that was solid correlated with the light extinction coefficient of the
mulches. Despite the well characterized allelopathic properties of rye (see