Diversity of rice weeds vegetation and its potential as local forage resource in Java, Indonesia

Dissertation N. Kumalasari, betreut durch Prof. Dr. E. Bergmeier und Prof. Dr H. Behling

 

Projektlaufzeit

2011-2014

 

Zusammenfassung

The  ecosystems  around  paddy  fields  in  Java  are  varied,  owing  to  differences  in  climate, altitude  and  traditional  farming  varies  across  villages.    The  main  objectives  of  the  present study were 1) to examine the diversity and composition of weed communities in paddy fields and their relation to environmental factors, agricultural practice and cultivation season; 2) to examine  the  effects  of  different  types  of  surrounding  vegetation  on  the  plant  diversity  in paddy  fields;  and  3)  to  evaluate  the  productivity  and  nutrient  potential  of  rice  weeds  as ruminant feed.  

We  studied  sites  in  six  areas  in  the  island  of  Java,  Indonesia,  i.e.  Cugenang, Karanganyar, Malang (400–850 m asl), Karawang, Brebes and Gresik (10–50 m asl). Samples of  vegetation  were  taken  in  a  period  from  October  2011  through  to  June  2012.  Each  site comprised 33 plots of paddy fields, 20 m²  in size and bunds 10 m²  in size.  The weeds were collected in cultivated paddy fields, fallows and on paddy field bunds.

In this research studies, the peak of rice cultivation in Java is around the wet season between October and February.  In the examined 198 paddy field plots we recorded 14 crop species  and  221  non-crop  plant  species  (weeds),  of  which  171  species  occurred  in  paddy fields and 190 on bunds.  Poaceae, followed by Asteraceae, were most common.  In the mid elevations we found higher mean number of species in each plot. Weed cover and diversity was higher in fallowed plots than cultivated plots. Six plant communities were identified by means  of  multivariate  analysis,  with  species  combinations  related  to  altitude,  herbicide application, water level and cultivation season. Elevation and water level gradients were the most important factors controlling species composition in paddy fields.

Weed management corresponds to water seasonality because farmer used water to flood their fields in order  to  control  weed  growth.  Flooding suppresses  the  growth  of  grass and certain broadleaved weeds. In fallows, twice as many species as in cultivated rice fields were found.    In  contrast,  the  presence  of  semi-natural  vegetation  within  short  distance  had  no significant effect on weed species numbers in paddy fields. Altogether, differences in weed species numbers and composition between areas are more pronounced than the effects of local environmental complexity.

Weed biomass in mid elevation areas was largest on bunds as a result of intensive weed control  in  paddy  fields.  In  the  lowlands  most  weed  biomass  was  on  fallows.  Fresh  weed biomass in the first rice growing season (after dry season) yielded 891–2369 g/m². Nutrient content  revealed  a  proportion  of  crude  protein  between  11.9–16.6%,  crude  fiber  between 31.6–39.6%, and crude fat 0.8–1.1%.

In  conclusion, a high variation in the diversity of weed was found across the studied paddy field types.   Mid-elevation paddy field is highly diverse in weeds than lowland paddy field.   Results show that altitude as well as water availability may support species richness.  Some  effects  differed  between  regions  correlated  with  different  agricultural  management, such  as  weeding  habits,  plant  cropping  and  cultivation  time.    However,  environment complexity  by  semi  natural  vegetation  did  not  influence  weed  number  in  paddy  fields.  Accordingly,  weed  biomass  and  nutrient  content,  thereby  abundance  of  rice  weeds  has considerable  potential  as  ruminant  feed.    Consequently,  to  conserve  and  support  species diversity and ecological function in paddy field and farming system, we suggest to enhance the integrated farming system included animal husbandry. Further, varied condition of semi natural  vegetation,  fallows  and  bunds  should  maintain  to  support  plant  diversity  and ecosystem functioning in paddy field.

 

Publikationen im Rahmen des Projekts

Kumalasari, N. (2014): Diversity of rice weeds vegetation and its potential as local forage resource in Java, Indonesia. Dissertation 70 S.

Kumalasari, N.R., Abdullah, L. & Bergmeier, E. (2014): Nutrient assessment of paddy weeds as ruminant feed in Java. Livestock Research for Rural Development 26, 59.

Kumalasari, N.R. & Bergmeier, E. (2014): Effects of surrounding crop and semi-natural vegetation on the plant diversity of paddy fields. Agriculture & Food Security 2014 3:15