Growing Rice Alongside Aquatic Life Reduces Need for Pesticides

Food and Agriculture
A local carp living with rice plants
A local carp living with rice plants in the co-culture experiment. Lufeng Zhao (CC BY 4.0)

While rice is an important staple in global diets, rice cultivation and production are not so eco-friendly. Most rice agriculture relies on pesticides and chemical fertilizers for higher yields and less issues with insects and weeds. Now, researchers have found a way to minimize pesticide use for rice fields, instead using aquatic animals to help stifle weeds and improve crop yields.

Conventional farming involves planting large monocultures, or fields of the same crop. That makes each crop vulnerable to pests and weeds, which could wipe out most of one field. As such, farmers use pesticides to prevent weeds, pests, and diseases from taking over the crops and to boost yields.

But some farmers are testing ways to grow their crops while using natural methods to keep away pests and weeds.

“One example includes farmers experimenting with growing aquatic animals in rice paddies,” said Liang Guo, study author and postdoctoral fellow at the College of Life Sciences at Zhejiang University in Hangzhou, China. “Learning more about how these animals contribute to rice paddy ecosystems could help with producing rice in a more sustainable way.”

The research, published in eLife, analyzes three experiments and four years of study. In each experiment, the study authors considered rice grown alone or alongside carp, mitten crabs, or softshell turtles. According to the study, growing rice alongside these aquatic animals helped prevent weed growth. 

The animals also improved decomposition of organic matter and ultimately provided better yields compared to the rice that was grown alone. The researchers found yields that were 8.7% to 12.1% higher than the control crop grown without the aquatic animals.

Lufeng Zhao, author of the study and a Ph.D. student at the College of Life Sciences at Zhejiang University, added that the nitrogen levels in the soil remained stable with the aquatic animals present, so less chemical fertilizers were needed for the rice. The animals were given feed, but they scavenged for up to half of their diet. In turn, the rice plants absorbed 13% to 35% of nitrogen from leftover feed that the animals didn’t eat.

“These results enhance our understanding of the roles of animals in agricultural ecosystems, and support the view that growing crops alongside animals has a number of benefits,” said Xin Chen, co-senior author of the study and an ecology professor at Zhejiang University. “In terms of rice production, adding aquatic animals to paddies may increase farmers’ profits as they can sell both the animals and the rice, spend less on fertilizer and pesticides, and charge more for sustainably grown products.”

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