Plant diversity in organic and conventional rice farming: a case study from Malsiripura, Kurunegala District, Sri Lanka
Date
2024-11-01
Authors
Premachandra, M. V. N.
Madawala, H. M. S. P.
Nanayakkara, B. S.
Abeysundara, H. T. K.
Boyagoda, S. H.
Gunaratne, A. M. T. A.
Journal Title
Journal ISSN
Volume Title
Publisher
Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka
Abstract
Use of chemical fertilizers in conventional farming contributes significantly to many environmental issues including biodiversity loss, whereas organic farming practices enhance
agro-biodiversity by promoting a healthier ecosystem and enhanced ecosystem services. This study investigates the effects of organic (using organic fertilizer and other organic
methods) and conventional farming (using chemical fertilizer, weedicides, pesticides and other conventional methods) on plant diversity in selected paddy fields in the intermediate
climatic zone of Sri Lanka, during “Maha season”. Vegetation sampling was conducted in rice fields (representing 12 quadrats per field, inside fields and along field bunds), covering
three growth phases of rice: vegetative (V), flowering (F), and ripening (R) using pin frame method. During V, F, and R stages, the organic paddy recorded a total plant abundance of
730, 1322, and 986 individuals, while conventional paddy recorded 429, 874, and 1349 individuals, respectively. Nearly 42%, 46% and 4% in organic paddy and 43%, 43% and 7%
in conventional paddy were of native, exotic and endemic plant species, respectively. Although 100% of plants belonged to weeds in conventional paddy, only 80% of plants in
organic paddy were weeds. The species richness was 13, 15, 15 in organic paddy and 7, 9 and 6 in conventional paddy for V, F and R stages, respectively. Shannon-Wiener diversity
indices were 0.44 ± 0.55, 0.68 ± 0.40 and 0.31 ± 0.42 in organic paddy, 0.35 ± 0.36, 0.57 ± 0.41 and 0.44 ± 0.49 in conventional paddy, for the three phases, respectively. Species
richness was significantly higher in organic than conventional farming in all phenophases. However, Shannon-Weiner Diversity Indices did not significantly vary among conventional
and organic fields for the Maha season. Conventional farming had greater evenness in all three phases (V = 0.178, F = 0.261, R = 0.191) than organic farming (V = 0.171, F = 0.258,
R = 0.103). The highest value of Simpsons’ Diversity index was reported in organic farming at F phase (5.07) followed by V (4.50) and R (3.45), and in conventional farming, the highest
was recorded for R (3.77), followed by F (3.75) and V (2.72). Cyperus rotundus was the most abundant species (excluding O. sativa) in both paddy fields during all phenophases.
The study underscores that while farming practices influence plant species richness, they do not significantly impact plant diversity.
Description
Keywords
Chemical fertilizer , Diversity indices , Organic fertilizer , Paddy field ecosystem , Paddy phenophases
Citation
Proceedings of the Postgraduate of Institute of Science Research Congress (RESCON) -2024, University of Peradeniya, P 172