Joint International Conference on Long-term Experiments ...

The a*cos(2π*i/12) periodic component value was 0,000131776, while b*sin(2 π
i*i/12) periodic component value was 2,80205E-05 between 2001-2006. Pi periodic
component and substances are demonstrated by Figure 3.
c
0,2
0,15
0,1
0,05
0
-0,05
-0,1
-0,15
-0,2
1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69
p ′ ′ + V ′
′ i = c1
∗ pi−1
1
N −1
1
N
N −1
∑
i=
1
′ 1 = r1
=
N
∑
i=
1
p
p
i
2
i
p
i−1
i
a*cos(2π*i/12)
b*sin(2π*i/12)
Figure 3. Time steps of biomass production periodic component and substances
After the isolation of the periodic component from the data source the autoregressive
and random components are remained.
During the interpretation of the prepared model the autoregressive component expressed
the connecting effect of biomass periods (year by year) which are written in plant
production practice as year effect while random component determines the uncertainty
of model.
Then analyzes was continued with determination of pi random component supposing the
trend and periodic component effects are not exist anymore. So there is only
autocorrelation between time series values. The one step autoregressive sub-model is
the following:
Pi
(eqv. 7.)
where t refers time step and Vi is autoregressive component, the c1is constant of the
above function.
c1’equal to autocorrelation factor, which is rj (Eqv.8):
49
(eqv. 8.)