Abstract:
The agronomic potential of rubber factory effluents as a
source of N, P and K for rubber and paddy plants was
investigated. Rubber serum obtained from coagulation tanks of a
crepe rubber factory, was tested as the "rubber factory
effluent'. Different dilutions of effluent and fertilizereffluent
combinations were evaluated on plant growth, plant
nutrient composition, yield and soil parameters in a series of
investigations. Clone PB 86 of rubber was tested in one green
house trial and one large scale field experiment and variety of
BG 94 - 1 of paddy was tested in four green house experiments.
Attempts were also made to determine the effect of land
application of rubber effluent on soil moisture status at
different depths under the field conditions in mature rubber
plantations.
Significant increases in soil and plant nutrient contents
and soil pH, were observed due to effluent application, in all
experiments. Significant increases in plant growth and yield were
also recorded in green house experiments.
Experiment conducted on young rubber seedlings showed that
half dilution is more effective than other dilutions, with regard
to plant growth. The effects of recommended fertilizer and
effluent - fertilizer combination were observed to be similar in
most of soil and plant parameters.
Field experiment was carried out according to a randomised
block design and specially manufactured storage tanks and
electric pumps were used for land application trials. Application
of undiluted and diluted forms of effluent on mature rubber in
field trials appeared to be equally effective in increasing leaf
N, P, K, Mg contents and soil P, K, Mgrcontents. No significant
changes in soil organic carbon, nitrogen, sodium and iron
contents were evident even after one year of effluent application
on land. A slight increase in latex production was also observed
during this period.
It was clearly observed that even undiluted effluent has a
good potential as a fertilizer for paddy without any adverse
effects on growth. Plants treated with recommended fertilizer,
undiluted effluent and fertilizer-effluent combination gave
almost similar grain yields.
Possibility of substituting different fertilizer components
of recommended fertilizer mixture for paddy was investigated. A
better response was observed with recommended NPK level in the
early stages of growth. However, at latter stages all serum and
fertilizer treatments showed similar effects on plant growth.
The cumulative effects of previously applied effluent on
paddy Plants, were evaluated after the harvesting of previous
experiment. All effluent (serum) combinations were equally
effective as the recommended fertilizer, with regard to plant
height. 'Serum only1 and serum + PK treated paddy Plants gave
higher yields than the recommended NPK level. There were no
adverse effects on plant growth or soil characteristics even
after the continuous application of effluent during the two
seasons in paddy cultivation.
