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A Preliminary Assessment of Sustainability of Paddy Cultivation Exposed to Organic and Conventional Systems: A Case Study in Moneragala District
By Admin | July 1, 2009
At present due to escalation of cost and availability of artificial inputs, the sustainability status in paddy cultivation is facing negative trends. Moreover owing to continued adoption of conventional and intensive farming practices has lead to serious environmental, Ecological & health concerns in many parts of the country.
Ecological low external input and organic agricultural concepts have proved that increased productivity is possible with less or no environmental pollution and strengthened sustainability indices in paddy production both locally &internationally.
The present exercise explored the existing paddy cultivation systems adopting both traditional &improved varieties under organic and conventional farming techniques in the Badalkumbura Divisional Secretariat of Moneragala District during yala season 2008. Grain yield component analysis of field grown paddy & also soil biological & physical status were measured and compared. Shoot and root growth and dry matter production of early growth were studied in a glass house at TRI Talawakelle. Bio assay was done at TRI laboratory.
Field grown improved varieties showed significantly greater yields under conventional systems than in the organic systems. Interestingly, improved varieties exposed to organic cultivation also performed better than traditional varieties under both conventional and organic systems. Similar trends were observed in the bio assay findings. Irrespective of the system studied though no of tillers per plant and the no of seeds per panicle were low; traditional varieties showed a greater percentage of productive tillers & filled grains per panicle indicating that the less incidence of pest and disease attacks in traditional cultivars. Straw yield was higher in the improved varieties irrespective of the system.
Soil microbial activity measured as CO2 evolution rate was significantly greater under the organic paddy systems. However soil physical properties presented as soil strength did not shoe significant differences. Organic practices excluding artificial inputs and environment friendly cultural practices i.e. organic manure, mulches, non-chemical pest & disease management etc have resulted in improving biological properties of the soil, though the impacts on physical properties would take some time. However, the mean no of earthworm burrows in organic paddy systems were comparatively greater than in the conventional systems.
The Predator: Pest ratio under conventional paddy systems irrespective of the cultivar was comparatively low. Environmental friendly pest and disease management practices under organic systems have shown to benefits natural enemies of economically important insect pests. Also organic cultural systems exhibited a greater species diversity in weed composition; amongst weeds the broad leaf category was higher showing a significantly lower competition and also easy to control.
The results of the preliminary impact assessment of rice cultivations exposed to organic & conventional practices indicated satisfactory positive sustainability indices. However cost: benefit analysis would necessarily asses for the long term sustainability of these systems.
In addition to direct effects there are immense amounts of indirect long term benefits achievable through organic paddy cultivation. Hence long term impact assessment for at least 3-4 consecutive seasons is proposed for better impact assessments.
R. Sandamali 1, Keerthi Mohotti 2
1- Univeristy of Peradeniya, Sri Lanka
2- Tea Research Institute, Sri Lanka
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