Abstract:
A living mulch system consists of growing a regulated cover crop
with an economic crop. Living mulches are often interplanted with
horticultural crops, but competition for water can adversely affect
crop production. Various management practices may limit the negative
effects.
Studies were conducted for two purposes: (1) to determine if
water use of perennial ryegrass (Lolium perenne L.) could be reduced
by mechanical or chemical suppression, and (2) to examine water-use
patterns and effects of a living mulch grown in strips between rows of
Douglas fir (Pseudotsuga menziessi M.) and grand fir (Abies grandis
D.) Christmas trees.
Small bucket-lysimeters were used to measure water consumption of
four treatments: bareground, and mechanically suppressed, chemically
suppressed, and unsuppressed perennial ryegrass, cv. Manhattan II.
Sublethal rates of fluazifop-P (butyl (R)-2-[4-[[5-(trifluoromethyl)-
2-pyridinyl]]oxy]phenoxy]propanoic acid) were applied to chemically
suppress the grass. Evapotranspiration (ET) calculated by the Food
and Agriculture Organization Blaney-Criddle method and actual ET data
were compared.
Unsuppressed ryegrass used 9% more water than ryegrass either
chemically or mechanically suppressed. Bareground used 61% less water
than the unsuppressed grass.
Results of the living mulch field trials indicated strips of
perennial ryegrass and indigenous vegetation grown between rows of
Christmas trees used more water than bareground, regardless of the
suppression treatment. Measurements taken during the study indicated
there were no significant differences in tree growth among treatments.
