On complex rice systems

Abstract

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, these phenomena explained why the rice yields increased along the gradient of complexity and this was consistent over time. As the last step, action research was carried out from 2014 to 2016 in four districts of East Java by modifying and simplifying the farmer field school (FFS) approach. Focus point was the selection of adaptation measures for CRS implementation in various socio-biophysical conditions. By modifying the FFS method, feedback from farmers was generated and used for adaptation of CRSs to the contextual conditions. Meanwhile, simplifying the procedures improved the cost-effectiveness of the FFSs. In summary, this thesis provides insights regarding the essential role of biodiversity as the basis for important agro-ecosystem services such as nutrient cycling and weed and pest suppression. This supports the development of knowledge and innovation of CRSs which result in highly stable rice yields and thus can contribute to safeguarding food security while the additional products potentially improve dietary and income diversity of rice farmer households. The fact that extreme weather conditions occurred during the experiments confirmed the high resilience and adaptive capacity of CRSs. Finally, the case study in this thesis can be used to guide CRS adaptation, but needs to be supported by active communication with stakeholders and appropriate training for farmers which are key drivers for large-scale implementation of these CRSs.