Diversifying crop rotations with temporary grasslands - Université de ...

C.II.4 Discussion
C.II.4.1 Differences between crop treatments
Results of this 2.5-year field experiment show that weed populations reacted in contrasted
ways
to the compared crop treatments. At the end, differences in weed plant densities,
diversities, biomasses and species composition were strongest between the annual and
perennial crops (cf. summary in Table 11).
Differences between autumn and spring-sown
perennial crops and between annual crops with or without soil tillage after harvest came at the
second and third places, while the other factors (forage crop species, cutting frequency and the
mustard intercrop) resulted in lower differences (Table 11).
Table 11: Summary of results for five crop treatment comparisons (detailed in previous Figures and Tables).
Treatment comparison
Criteria Time
Crop type Species
Sowing
season
Cutting Tillage in
frequency intercrop
Annual vs. Dactylis vs.
Perennial Medicago
Spring vs.
3 vs. 5/year
Autumn
With vs.
without
Emerged weed plants
Density (Fig. 12A, Fig. 13)
Beginning P >> An
End An >> P
=
M > D
=
D: A > S
=
=
=
T+ >~ T-
Diversity (Fig. 12B)
Beginning P >> An
End An >> P
=
M >> D
S > A
S > A
=
C- >~ C+
=
=
Ratio richness/abundance (Fig. 12C)
Beginning An >> P
End P >> An
=
D > M
A >~ S
=
=
=
=
=
Biomass (Fig. 17)
Beginning
End
P > An
An >> P
D > M
=
S >> A
=
=
=
=
=
Species composition (Table 9)
Beginning
End
≠ ≠
≠ ≠ ≠
=
≠ ≠
≠ ≠
≠
=
M: ≠
=
≠
End; last months of the experiment; Beginning; first months of the experiment; An, Succession of annual crops;
P, Perennial crops; D, Dactylis glomerata; M, Medicago sativa;
S, Spring-sown; A, Autumn sown perennial
crops; C-, cut 3 times per year; C+, 5 cuts/year; T-, without soil tillage during intercrops; T+, with soil tillage;
>>, much higher than (white cells); >, higher than (light grey cells); >~, tends to be higher than (grey cells); S: /
D:, differences exist only for Spring-sown / Dactylis crops; ≠ ≠ ≠, very strong differences (white); ≠ ≠, strong
differences (light grey); ≠, medium differences (grey); =, no differences (black).
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