Agriculture Reference
In-Depth Information
summers of 1993 (at the onset of the experiment), 1995 and 1997 (at the
end of the first and second rotation cycles, respectively). Thanks to a low
soil heterogeneity, four soil sub-samples were taken in each plot down to a
30 cm depth (0-7 and 7-30 cm layers) by means of a 2-cm diameter probe,
and then pooled to obtain a bulk sample. Total soil organic matter content
(Walkley-Black method) and aggregate stability (Malquori method) were
measured at each sampling date, whilst total N (Kjeldahl method) and
assimilable P
2
O
5
(Olsen method) were measured in 1993 and 1997. To
reduce variance heterogeneity, soil organic matter and total N percentage
data were transformed to
√
(
x
+ 0.5) while P
2
O
5
data were transformed to
arcsin
(
x
) prior to statistical analysis. Data were then subjected to analysis
of variance according to a split plot experimental design. The analysis of
variance was carried out separately for each year and, after carrying out
Bartlett's test, a combined analysis over years was performed using the time
factor as a random variable. ANOVA results are shown in Table 3.8.2.
√
Results
Soil organic matter was affected significantly and differently by the
management systems during the experimental period as shown in Table
Fig. 3.8.1.
Soil organic
matter: 'year
management
system' interaction.
×
Search WWH ::
Custom Search