Agriculture Reference
In-Depth Information
sustainability of the production of a crop or a
particular cropping or management system is
essential for future food security. Quite a few
studies have been attempted to measure the
sustainability and thereby compare the different
competitive methods or processes in agriculture.
Some of the works to mention, though not exhaus-
tive, are of Soni et al. (
1988
), Narayan et al.
(1990), Singh (1990), Katyal et al. (
1998
,
2000
),
Gangwar et al. (
2003
), Sahu et al. (
2005
), and
Pal and Sahu (
2007
), etc. To frame a measure
for sustainability, well-planned long-term experi-
ments of different crops, cropping systems, or
farming systems under a given situation are very
useful. But such planned experiments for a long
period of time are very rare in literature except a
few like the long-term experiments conceived and
continued in Rothamsted Experimental Station,
UK. In India, experiments have been started
during the late 1980s of the twentieth century to
study the long-term behavior of crop, cropping
system, nutrient management system, etc. Let us
discuss some of the indices of yield sustainability
under the above long-term setup.
Let us suppose that we have an experiment
conducted with
consecutive
years on the same crop/cropping system. Then
we have the yield sustainability indices:
i
treatments for
j
Þ¼
y s
Sustainability index SI
ð
1
y
max
ð
Singh et al
:
1990
Þ
,
where
y; s; y
max
are the average
;
standard deviation and maximum yield respective
of a particular crop
=
cropping sequence or nutrient treatment over a period of time
:
The higher the value of the index, the higher
the sustainability status but with no definite
range:
;
1
b
i
Sustainability index SI
ð
2
Þ¼
where
b
i
is the regression coefficient in
y
ij
¼ a þ b
i
y
j
; ð
ICARDA 1994
Þ
where
y
ij
is the yield corresponding to the
i
th
In an attempt to improve the above measure
of ICARDA (
1994
) and Katyal et al. (
2000
)
introduced a time coefficient in the above regres-
sion. Thus, the regression takes the shape of
y
ij
¼ a þ b
i
t þ c
i
y
j
is the
treatment in the
j
th time period, and
y
j
overall mean yield for
the
j
th time period.
According to this method,
b
i
value, the lower the sustainability and vice
versa. In this method also,
the higher the
and is
the
time period
(Katyal et al. 2000).
According to this method sustainability index
is given as
the sustainability
index does not have any limit.
;
1
c
i
y
j
Sustainability index SI
ð
3
Þ¼
where
c
i
is the regression coefficient in
The decision rule is similar to that of index 2.
