On complex rice systems

Abstract

Uma Khumairoh, 2019. On complex rice systems. With summaries in English, Dutch, and Indonesian, 178 pp.The escalating global rice consumption has put great pressure on rice production systems which have been challenged by increased variability in weather conditions and concerns about environmental impacts. Meanwhile, current innovations in rice production systems confirm that there are no single solutions that comprehensively address those complex challenges. Therefore, integrated solutions are required to improve and stabilize current rice production levels and their environmental sustainability. To this end, this thesis aimed to develop bio-diversified rice-based farming systems by combining diverse plant and animal species as well as traditional and modern rice cultivation methods. This approach is referred to as complex rice systems (CRS), which have the ultimate goal to improve rice yields and their stability along with the whole farm productivity in an ecological way. This led to the selection of azolla, fish, ducks, and border plants for generating ecosystem services of weed and pest suppression as well as nutrient recycling. These were integrated using three selected cultivation methods: (i) the system of rice intensification (SRI), (ii) 'jajar legowo' and (iii) organic rice production. Jajar legowo is planting rice in straight rows at certain intervals, allowing more rice plants to receive sunlight. We hypothesized that a combination of these cultivation methods and finetuning of biodiversity management could lead to high and stable rice yields with additional extra benefits from various secondary products.To test this hypothesis, we conducted on-farm field experiments and perform action research in four districts of East Java, Indonesia, from 2010 to 2016. In 2010, we conducted an experiment with nine treatment combinations along a gradient of complexity to investigate their effects on attainable rice yields. We found that rice yields improved with increasing level of complexity and that the highest yield was obtained under the most complex system comprising all components (i.e. rice, azolla, ducks and border plants). Consistently, high yields under CRSs across four locations and throughout three rice cropping cycles were observed in an experiment performed between 2014 and 2016. CRSs showed both static and dynamic stability, had the highest reliability index, and were therefore outperforming the conventional and organic monoculture systems.The mechanisms underlying the established high and stable rice yields of CRSs were elucidated in a multi-year experiment over five rice cropping cycles conducted from 2013 to 2016. The results demonstrated that increasing the level of complexity resulted in lower levels of weed and pest infestation. Analysis of duck behaviour and their gizzard composition showed that ducks foraged intensively on weeds, insects, snails and azolla. Furthermore, nutrient cycling was accelerated by ducks via feeding and excretion as well as by their movement in the field. Altogether, the...

Groundwater-Extracting Rice Production in the Rejoso Watershed (Indonesia) Reducing Urban Water Availability: Characterisation and Intervention Priorities

“…Current agricultural practices lead to high methane (CH 4 ) and nitrous oxide (N 2 O) emissions, high intensity of pest and diseases and low agricultural yield. Water-saving techniques are expected to be financially and environmentally beneficial to smallholders by enhancing their resilience to shocks and improving the capacity of the production landscape to generate ecosystem services [23]. Nevertheless, introducing sustainable paddy cultivation beyond the current, conventional practices is a challenge, as behavioural changes and biophysical conditions vary.…”