Abstract:
Big onion (Allium cepa L) is utilized as a main condiment in Sri Lankan dishes, where it is
considered as an important cash crop grown in dry zone of Sri Lanka. Success of onion cultivation
is largely depending on the optimum cultural and management practices such as application of
organic manure and chemical fertilizers, optimum irrigation schedule, proper weed management
and time of planting. Mulching is a smart management practice, in which has been reported to be
influence on soil moisture conservation, control of soil erosion and compaction and regulating soil
temperature. Since application of mulching has not been extensively studied in big onion
cultivation under Sri Lankan conditions; a study was carried out to find out a suitable mulching
material which can increase the bulb yield. An experiment was conducted at the Agriculture
Research Station, Weerawila, which belongs to DL5 agro ecological zone and the experiment was
laid out in randomized complete block design (RCBD) with three replications in three consecutive
seasons (2015 Yala, 2017 Yala, 2018 Yala). Treatments were comprised of seven mulching
materials (black polythene, White polythene, paddy straw, saw dust, paddy husk, wood creeper
and partially burned paddy husk (PBPH). Results indicated that the bulb yield has shown
significant difference (P=0.05) between each mulching treatment, in which the PBPH has shown
25% increase in bulb yield in comparison to the control. In addition, all the mulching materials
have shown yield advantage during the tested seasons. Further, soil temperature with the
application of artificial and natural mulching materials have shown a variation although not
statistically tested. Interestingly, paddy husk mulch has recorded the lowest soil temperature
while the highest was recorded in the white polythene mulch. Analysis of the economic returns of
the mulching suggests that the partially burn paddy husk and black polythene mulching is
superior and thus dominant over other mulching materials. Considering the availability of paddy
husk in Hambantota district and considering the environment issues, the partially burned paddy
husk can be recommended for the big onion cultivation.
