Co-Cultures: Growing together gives more rice and aquatic food
Allowing aquatic organisms to grow in rice fields – a practice called co-culture – increases rice yields while maintaining soil fertility and reducing weeds.
-
Download
A two-part list of links to download the article, or parts of the article, in various formats.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
Co-Cultures: Growing together gives more rice and aquatic foodeLife 11:e77202.https://doi.org/10.7554/eLife.77202 - Cite
- CommentOpen annotations (there are currently 0 annotations on this page).
- School of Environment and Sustainability, Global Institute for Water Security, University of Saskatchewan, Canada
- Department of Biosystems and Technology, Swedish University of Agricultural Sciences, Sweden
When you eat rice with fish – or rice with crab or shrimp – you probably do not think about where the food came from. And if you do, you probably think that the rice grew in a paddy field, while the fish, crab or shrimp were caught in the sea. However, this may only be partially true. Systems for growing rice and various aquatic animals together have existed for over 1,200 years, but the practice of ‘co-culture’ has only recently gained the attention of the major rice-producing nations and the scientific community (Xie et al., 2011).
Rice is one of the most widely consumed grains in the world and is grown in more than 100 countries. It is a staple food source for over half of the world’s population and of upmost importance for lower income countries in Asia, Latin America and Africa (Bashir et al., 2020). Climate change, declining natural resources and an ever-growing population put immense pressure on both increasing yields and reducing the environmental footprint of rice (Hu et al., 2016; Ahmed and Turchini, 2021). Global trends are thus moving towards sustainable and organic management of biological resources (Chen et al., 2014; Muller et al., 2017). Strategic coupling of terrestrial and aquatic ecosystems, such as growing crops and aquatic animals together, could help meet this target (Ahmed and Turchini, 2021).
Previous research has shown that co-cultures can boost yields, improve soil health and enhance ecosystem services (Mueller et al., 2012; Campanhola and Pandey, 2019). But even though co-culture systems would help optimise the use of land and water resources to produce food – while reducing the environmental impacts associated with rice monocultures – large-scale and long-term data are lacking (Bashir et al., 2020).
Now, in eLife, Xin Chen and colleagues at Zhejiang University and Bioversity International – including Liang Guo and Lufeng Zhao as joint first authors – report new evidence in support of co-cultures with aquatic animals and rice crops (Guo et al., 2022). Between 2017 and 2020, the team conducted three separate field experiments in which rice was grown with either fish, crabs or soft-shelled turtles. Each set-up also included a control experiment, where rice was grown as a monoculture. No agrochemicals were used to control weeds, pests or diseases during the field trials.
Over the four years, the co-cultures demonstrated multiple benefits (Figure 1). Rice yield was consistently higher in fields containing aquatic animals (between 8.7% and 12.1%). Moreover, the team was also able to harvest significant amounts of fish, crab and turtle as food (between 560 and 2660 kg/ha). Co-cultures also had fewer weeds and maintained consistent levels of mineral nutrients (nitrogen and phosphorus) in the soil. Moreover, the breakdown of organic matter happened faster in the co-cultures.
Figure 1
The benefits of co-culture for growing rice.
Guo et al. showed that growing rice with aquatic animals (fish, crabs or turtles) increases rice yield, suppresses the growth of weeds, and maintains the levels of nitrogen and phosphorus in the …
Animals are instrumental in moving elements, such as carbon, nitrogen and phosphorus, in the environment (Schmitz et al., 2018). To find out whether the biology of a co-cultured animal would affect the growth of rice, Guo et al. carried out three additional, controlled experiments to trace the movement of nitrogen from feed (labelled with stable isotopes) to aquatic animals and the environment.
Analyses of the animal’s food intake revealed that fish and crabs obtained up to half of their diet (50% and 35%, respectively) from the rice fields, consuming algae, phytoplankton or weeds. Turtles relied more on additional feed, and only derived 16% of their food intake naturally. The animals’ wastes and any uneaten feed also increased the nutrient availability for the rice plants: rice plants used up to a third of the nitrogen from the animal feed.
The work of Guo et al. demonstrates clearly how co-cultures could make agriculture more sustainable, by increasing soil fertility and reducing the need for fertilizers or pesticides. Moreover, these coupled systems could also help fight the spread of malaria by introducing natural, co-culturing predators, such as frogs (which eat the mosquitos) and fish (which eat the mosquito larvae), and so contribute towards several ‘Sustainable Development Goals’ of the United Nations (Khatiwada et al., 2016; Campanhola and Pandey, 2019).
More research is needed to better understand the impact of co-culture on greenhouse gas emissions and nutrient pollution (Bashir et al., 2020). Nevertheless, these experiments provide a good foundation for further studies to explore how agriculture can be made more sustainable.
References
-
The evolution of the blue-green revolution of rice-fish cultivation for sustainable food productionSustainability Science 16:1375–1390.https://doi.org/10.1007/s11625-021-00924-z
-
Co-culture of rice and aquatic animals: An integrated system to achieve production and environmental sustainabilityJournal of Cleaner Production 249:119310.https://doi.org/10.1016/j.jclepro.2019.119310
-
Can the co-cultivation of rice and fish help sustain rice production?Scientific Reports 6:28728.https://doi.org/10.1038/srep28728
-
Frogs as potential biological control agents in the rice fields of Chitwan, NepalAgriculture, Ecosystems & Environment 230:307–314.https://doi.org/10.1016/j.agee.2016.06.025
-
Animals and the zoogeochemistry of the carbon cycleScience (New York, N.Y.) 362:eaar3213.https://doi.org/10.1126/science.aar3213
Article and author information
Author details
Acknowledgements
The authors would like to thank SLU Aquaculture and Jordbruksverket for financial support.
Publication history
Copyright
© 2022, Liu et al.
This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 1,340
- views
-
- 143
- downloads
-
- 4
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
Further reading
-
- Ecology
Global change is causing unprecedented degradation of the Earth’s biological systems and thus undermining human prosperity. Past practices have focused either on monitoring biodiversity decline or mitigating ecosystem services degradation. Missing, but critically needed, are management approaches that monitor and restore species interaction networks, thus bridging existing practices. Our overall aim here is to lay the foundations of a framework for developing network management, defined here as the study, monitoring, and management of species interaction networks. We review theory and empirical evidence demonstrating the importance of species interaction networks for the provisioning of ecosystem services, how human impacts on those networks lead to network rewiring that underlies ecosystem service degradation, and then turn to case studies showing how network management has effectively mitigated such effects or aided in network restoration. We also examine how emerging technologies for data acquisition and analysis are providing new opportunities for monitoring species interactions and discuss the opportunities and challenges of developing effective network management. In summary, we propose that network management provides key mechanistic knowledge on ecosystem degradation that links species- to ecosystem-level responses to global change, and that emerging technological tools offer the opportunity to accelerate its widespread adoption.
-
- Ecology
- Evolutionary Biology
Eurasia has undergone substantial tectonic, geological, and climatic changes throughout the Cenozoic, primarily associated with tectonic plate collisions and a global cooling trend. The evolution of present-day biodiversity unfolded in this dynamic environment, characterised by intricate interactions of abiotic factors. However, comprehensive, large-scale reconstructions illustrating the extent of these influences are lacking. We reconstructed the evolutionary history of the freshwater fish family Nemacheilidae across Eurasia and spanning most of the Cenozoic on the base of 471 specimens representing 279 species and 37 genera plus outgroup samples. Molecular phylogeny using six genes uncovered six major clades within the family, along with numerous unresolved taxonomic issues. Dating of cladogenetic events and ancestral range estimation traced the origin of Nemacheilidae to Indochina around 48 mya. Subsequently, one branch of Nemacheilidae colonised eastern, central, and northern Asia, as well as Europe, while another branch expanded into the Burmese region, the Indian subcontinent, the Near East, and northeast Africa. These expansions were facilitated by tectonic connections, favourable climatic conditions, and orogenic processes. Conversely, aridification emerged as the primary cause of extinction events. Our study marks the first comprehensive reconstruction of the evolution of Eurasian freshwater biodiversity on a continental scale and across deep geological time.
