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by KeAi Communications Co.

The study shows that the right policy to reduce the use of pesticides is critical to food security.

Modeling the impact of Shanghai’s pesticide reduction policy on the environment and food security. Credit: Youquan Zhang

The term “suburban agriculture” is commonly used to describe the cultivation of plants and livestock on the outskirts of large population centers. However, factors such as urban growth, rising labor costs and limited labor supply are putting increasing pressure on suburban agriculture. As a result, agribusinesses are looking for ways to minimize workload and increase yields; for example, many rely more on pesticides; a step that could negatively affect the urban environment and its inhabitants.

In a study published in Basic Research, researchers from China and the United States studied the agri-food and environmental impacts of a policy to reduce the use of agrochemicals (pesticides) introduced in metropolitan Shanghai, east China. The policy aims to reduce the use of agrochemicals by 20% by 2020 compared to 2015. Official statistics show that Shanghai has achieved this goal by reducing pesticide use by just over 40% (from 4,415 to 2,644 tons). However, the cultivated area decreased by almost 25% over the same period (from 340,200 to 255,200 ha), with production of major crops falling by 18% and vegetable production by 31%. This is despite the municipality’s stated goal of keeping suburban agriculture as intact as possible while guaranteeing food security.

While other factors, such as urbanization, have contributed to the reduction of the city’s suburban hectares, questions remain about the extent to which pesticide reduction policies have played a role, said Yuquan Zhang, co-author of the article, from Shanghai Jiao Tong University in China. . To measure the impact of policy, he and his colleagues worked with Bruce McCarl, professor and specialist in GAMS (General Algebraic Modeling System) at Texas A&M University in the US. Together, they developed a new optimization model that mimics Shanghai’s suburban agricultural sector, rich in crop and area-specific input use data, including pesticides. They then examined the impact of a number of pesticide use reduction scenarios, including the Shanghai Municipality’s 20% target.

The team found that applying existing reduction policies at the district and regional levels led to significantly different results. When all districts followed the 20% reduction order, both rice and vegetables (leafy greens and cabbage) experienced a marked reduction in planted area, resulting in lower production levels. However, for areas such as Chongming (northern island) and Qingpu (western island), this reduction in area and the use of pesticides also had a positive effect, reducing the pollution of the mouth of the Yangtze River and Dianshan Lake. The latter is an important source of drinking water.

At the regional level, the requirement for a 20% reduction has led to a significant reduction in the area under cultivation of peri-urban farmland in pesticide-intensive areas such as Chongming and Qingpu, and marked changes in crop composition, which has greatly affected rice. The team also found that the introduction of equipment for more precise application of the pesticide had a positive effect on the results of the model.

Zhang concludes that “although Shanghai cannot currently feed itself, given its huge population (over 24.87 million) and limited available land, residents’ strong appetite for leafy vegetables means the city must be able to grow enough vegetables to meet about 85% of this demand. However, the disadvantage is that vegetables usually require significantly more agrochemicals than field crops. And the crop mix in Shanghai is dominated by non-grain crops, which often require large amounts of pesticides.”

“Surface runoff from this suburban agriculture has been a major source of water pollution. Our research shows that when use quantity control policies are implemented at the regional level rather than the one-size-fits-all district level, both can achieve improved agri-food impacts and improved environmental outcomes, rather than the drastic trade-offs we so often see.” .


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Additional Information:
Yuquan W. Zhang et al. Operational Reduction of Pesticide Use in Suburban Food Security Framework, Basic Research (2022). DOI: 10.1016/j.fmre.2022.04.003

Provided by KeAi Communications Co.

Quote: Study Shows Good Pesticide Reduction Policies Are Critical to Food Security (2022 June 23), retrieved June 23, 2022 from https://phys.org/news/2022-06-pesticide-reduction- policies-crucial-food.html.

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