full paper - THE BIOSCAN

U. K. SAHOO et al.,
community (i.e. 300). The dominance index (Simpson, 1949) of the community was calculated as: C=” {(n i
/
N) 2 }, where C=dominance index, n i
and N are same as for Shannon’s index. Pielou’s (1966) evenness index
(e) was calculated as: e= H’/logS, where H’= Shannon’s index of diversity, and S= Total number of
species. Sorenson’s similarity index (Sorenson, 1948) was calculated as, [2C/(A+B)] x 100], where, A and
B are the total species content (trees, shrubs or herbs) in stand A and B respectively, while C is the number
of species common to both stands.
Soil analysis
Five cores (6.5 cm inner dia) from 0-15 cm and 15-30 cm depth were collected from each selected homegarden
in the month of March. All the soils collected were pooled garden-wise and depth-wise and sieved through
2mm mesh screen. The soil moisture content (SMC), pH, ammonium-N and nitrate-N were determined
within 36 hours of sampling following standard procedures given in Anderson and Ingram (1993). Rest of the
soil samples were air-dried and analyzed for total kjeldahl nitrogen (TKN) using Kel Plus (Pelican model),
while available phosphorous and soil organic carbon (SOC) was estimated by molybdenum blue method and
rapid titration method respectively as given in Allen et al. (1974). Water holding capacity (WHC) was
determined using Keen’s box and the SOC values were multiplied by a constant (1.724) to obtain the soil
organic matter (SOM) values (Allen et al., 1974). Soil texture was determined by Boucous hydrometer
method (Anderson and Ingram, 1993).
Microclimatic variables
The microclimate in the home gardens were studied by measuring light intensity, relative humidity and air
and soil temperatures. The light intensity was measured using a digital lux meter. The air temperature and
relative humidity were measured using a thermo-hygrometer. Soil temperature was measured using a soil
thermometer.
Energy input/output
A process analysis was used to measure energy flow (Fluck, 1992) adding human work contributions (Odum,
1996). Internal and external inputs were measured in Mega Joules (MJ). These were estimated by extrapolating
standard energy values (Mitchell, 1979; Mittal and Dhavan, 1989 and Gopalan et al., 1982). The input of
energy through seeds was calculated on the basis of total energy expended to produce that fraction of the
crop yield. The economic yield per hectare in all cases was calculated on the basis of the entire plot. For
calculating the output of energy the total economic yield of various crops was converted into mega joules of
energy by multiplying with similar standard values. The energy efficiency of each system was calculated as
the output/input ratio.
Input of household labour is a component that needs to be factored to an economic valuation. For the purpose
of this study, opportunity cost of household labour is calculated as a function of time, OC HL
=ƒ (t * labour
rate), where t is the time spent in the garden. The opportunity costs of land have been assigned values
equivalent to the rate at which farmers were able to lease out all or parts of their lands. This rent was
calculated to be an average of Rs. 9500 per hectare of the land per year. For monetary input/output analysis,
labour charge was calculated on the basis of prevailing daily rates of Rs 70. The monetary returns in terms
of crops, feed, milk, egg and organic manure were calculated based on prevailing market price for each
commodity.
RESULTS AND DISCUSSION
Garden size, vegetation composition and dynamics
The size ranged from 144 m 2 to 0.9 ha with a mean of 0.3 ha area. The average homegarden size in small
category was 1152 m 2 , 3895 m 2 in medium and 8500 m 2 in large gardens in the three different villages. The
altitudinal range varies from 56 m asl to 960 m asl. The location of the homegarden in the three villages
ranged from 23º48´58.2½ N to 23º54´53.5½ N latitude and 92º29´41.9½ E 92º25´27.4½ E longitude.
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