| dc.description.abstracteng | 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. | de |