Information on the general features of farms, farm operations
and energy utilization from 59 questionnaires (or farms) shows
a wide range of the amount of resource inputs (Table 2). Such
variations are reflected in the difference between the median and
the mean values. In most cases median of the data set is smaller
than the mean value. Questionnaire results show that the average
farm size of sugarcane growers in this region was 27 17.7 ha
(meanstandard deviation from 59 questionnaires). The farm
sizes can be further divided into a small (1.6e10 ha) with 15%,
medium (>10e30 ha) with 47%, and large farms (>30e96 ha) with
38% of the total sugarcane area (Table 2). The yield ha1 varies with
the farm size; the smaller farms had a lower yield in general but did
not have any statistical significant difference. The cane yield was
not statistically related to the amount of fertilizer application. The
overall yield range was 32e120 ton ha1, and about 40% of farms
had the yield less than 60 ton ha1. The low sugarcane productivity
is partly due to the low soil fertility associated with sandy soil and
with the long period of land use for sugarcane cultivation (Land
Development Department, 1993). From the interviews, most of
the farmers have continued growing their sugarcane for more than
20 years. Thus, the emissions from land used changed to sugarcane
was not accounted for in this study.
Sugarcane yield was sent as feedstock to sugar mills located
within eastern Thailand. On average, the farms were located about
2014.7 km (meanstandard deviation from 59 questionnaires)
away from the sugar mills. Average diesel consumption for transportation
was 2.5 km per liter. There was no obvious difference
among farm sizes in terms of distance to the sugar mills, but the
amount of fertilizer, herbicide and insecticide varied with the farm
size (Table 2).
It is worth noting that the N fertilizer application rate varied
significantly (a factor of 18) from 19 to 938 kg-N ha1, while the
yield varied by merely a factor of 3. In addition to the dependence of
yield on nature of soil and its fertility level, it may also indicate that
some improvements in fertilizer application may be possible so
that less fertilizer is used and the yield is not significantly affected.
Greenhouse gas emissions from excessive use of fertilizer could also
be reduced.
Irrigationwas usually carried out during the start of the growing
season, since sugarcane was planted in March before the rainy