Agriculture Reference
In-Depth Information
The changing cropping pattern was worked out assuming that it follows a fi rst
order Markov chain [8], as explained below.
A fi rst order Markov chain is characterized by the transition probability matrix
[Eq. (1)].
pp
...
...
p
⎡
⎤
n
11
12
1
⎢
⎥
pp
p
⎢
⎥
21
22
2
n
P
=
(1)
⎢
⎥
...
...
...
⎢
⎥
⎢
pp
p
⎥
⎣
⎦
n
1
n
2
nn
where:
p
ij
is the probability that an area under the classification '
i
' during the current
year changes into the classification '
j
' next year and '
n
' is the number of states. There-
fore,
p
ij
is defined by Eq. (2).
p
=
Pr{
X t
(
+
1)
=
j
/
X t
( )
=
i
}
(2)
ij
where:
X(t)
= State of the system at the year '
t
.' It is clear that
p
ij
³ o
,
i, j = 1,2….,n
and
jn
=
∑
p
=
1
, i = 1,2…,n
(3)
ij
j
=
1
The transition probability matrix for the study was 9 × 9 matrix resulting in 81 un-
known probabilities
p
ij
,
i, j
= 1, 2, …, 9, which were estimated using farm level data.
In this study, the structural change in cropping pattern after introduction of drip irri-
gation system was examined by using the Markov chain approach. The estimation of
the transitional probability matrix (
P
) was central to this analysis. The element
P
ij
of
the matrix indicated the probability that the area would switch from the
i
th crop to
j
th
crop over a period of time, that is, after the introduction of drip irrigation system. The
diagonal elements (
P
ij
)
indicated the probability that the area share of a crop would be
retained in the successive time periods.
2.3 THE STUDY AREA
2.3.1 DRIP IRRIGATION IN TAMIL NADU
Tamil Nadu state stands seventh in the country in terms of area under micro irrigation.
During 2008, a total area of 158,521 hectares was practiced under micro irrigation in
the Tamil Nadu state. Of the total area under micro irrigation, the drip accounted for
82.85% (131,335 ha) and sprinkler for 17.15% (27,186 ha). At the national level, the
area under drip irrigation was 36.82% and under sprinkler was 63.18% (Fig. 1). It is
clear that the drip method of irrigation is more popular among the farmers in Tamil
Nadu when compared to sprinkler method of irrigation. It is seen that the Tamil Nadu
state has only 9.2 per of the total drip area in the country where as the sprinkler irriga-
tion accounts for only 1.1% of total area in the country. The area under micro irrigation
accounts 4.1% of the total area under irrigation in the country.
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