systems (consistent with substrate
diversity and availability). Likewise,
differences in community metabolic diversity between spring
2008 and summer 2010 may have
been due to higher soil organic
matter turnover rates in summer
compared to spring.
The higher summer community
metabolic diversity in T2 (work
rows seeded with cover crops each
winter), compared with T1 (weedcovered work rows) may have
been due to carry-over from the
work rows into the tree rows,
across the drip line from which the
samples were taken. If so, the win-
ter cover crop, which was chemically controlled in spring, may
have stimulated community metabolic diversity by releasing a greater variety of carbon compounds
into the soil through root exudation and decomposition, than did
the uncontrolled weeds, which
persisted into summer.
Table 2: Effect of conventional (CON) and organic (ORG) management on community metabolic diversity,
indicated by positive wells (carbon sources utilised) on Biolog Eco Plates™, in a ‘Cripp’s pink’/M7 apple
orchard. Values within the same column followed by the same letter do not differ significantly at p < 0.05.
Community metabolic diversity (%)1
Treatment
1
2008
2009
2010
Mean
spring
spring
summer
T1 (CON)
70.97e
71.77de
70.16e
70.97