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Take a look at the above interactive map (courtesy of the World Bank) which shows the percentage of land area in agriculture for different countries (2010-2014 data). In 2012, 44.7% of the United States land area was agricultural. In China, 54.8% of the land was in agricultural use. Even small changes in how we farm are important because agriculture takes up such a massive chunk of terrestrial Earth. For large countries with lots of agricultural land, policies impacting farmer education and management practices are particularly important. That’s why it’s interesting to see this new paper by Zhang et al. (2015) in the journal Science of the Total Environment. They surveyed 246 Chinese farmers from the Guangdong, Jiangxi, and Hebei provinces to get an idea of farmer knowledge about pesticides, and to find out what they used and how much. They looked at corn, rice, cotton, and wheat crops.There were a lot of interesting findings, but generally they found cases of both “overuse” and “underuse” of pesticides. What they mean by overuse is basically that the farmers often used way higher rates than the labeled amount, particularly for insecticides. For example, if you exclude cases where farmers used zero pesticides, the average dose of active ingredient used against wheat armyworm was 14-fold higher than the highest labeled rate. There was a lot of inappropriate mixing of pesticides too.
The authors also indicate that in as many of 20% of cases, farmers “underused” pesticides, which indicates that yields could be increased substantially with better IPM practices. However, the authors did not incorporate scouting to verify pest densities in fields, so it’s unclear if the lack of spraying truly represents sub-optimal (economically speaking, of course) pest management.
Overall, they found a lack of education among farmers about the proper use of pesticides. They attribute this in part to commercialization of the Chinese agricultural extension system in the mid- to late-1980s (see also Hu et al. 2009 China Economic Review). Only 3.3% of farmers surveyed get their information from the extension service, while 56.7% rely on vendors with obvious conflicts of interest.
There is so much great agricultural research that comes out of China, but it’s hard for me to always understand the context of experiments based on Materials and Methods alone. Zhang et al. (2015) give me a better idea of what Chinese agroecosystems are really like.
Image: Graphical abstract from Zhang et al. (2015) Sci Total Environ