Ph.D & Professor Nian-Feng Wan
Agricultural intensification, mainly due to the conversion of natural habitats into monoculture farming areas in which agrochemicals are intensively used, has been shown to do great damage to the environment and the resources on which we all depend. To alleviate these negative effects, ecologists have proposed the idea of “ecological intensification”.
The idea behind ecological intensification of agriculture is to use resource more efficiently, and to reduce agrochemical inputs by using natural ecological processes in agricultural production, which will benefit the environment. After several years of research and exploration, ecologists have found several potential ways to do this. It has been shown that increasing species diversity in agricultural fields through the use of ground covering vegetation, trap cropping, intercropping, and crop-fish co-culture can contribute to ecological intensification of agriculture by increasing natural enemies (invertebrate predators and parasitoids) of pests, decreasing invertebrate herbivore abundance and herbivory damage to crops and thereby decreasing the use of pesticides. These processes can also improve soil quality and increase crop yields, and contribute to increased ecosystem services, the services provided to humans by nature.
Ground cover vegetation in peach orchards in the suburbs of Shanghai, China (Photo: Nian-Feng Wan)
Trap crop (sunflowers) intercropped in peach orchards lure female adults of peach moth borers to lay eggs in sunflower heads in the suburbs of Wuxi City, Jiangsu Province, China (Photo: Nian-Feng Wan)
Soybeans and maize were interplanted around the rice fields on Chongming Eco-island of China. (Photo: Nian-Feng Wan)
Rice-fish co-culture on Chongming Eco-island of China. (Photo: Nian-Feng Wan)
Vegetable-fish co-culture on Chongming Eco-island of China. (Photo: Nian-Feng Wan)
It has been shown that, at a large scale that crop species diversity from intercropping promoted ecological intensification of agriculture (Gurr et al., 2016). Similarly, the presence of a border crop of soybeans and neighboring crops (maize, eggplant and Chinese cabbage) increased invertebrate predator abundance, decreased the abundance of herbivores and dependence on insecticides, and increased rice yield and economic profits (Wan et al. 2018). More studies are needed on how ground cover vegetation or trap cropping affects ecological intensification of agriculture.
Besides plant species diversity, rice-fish co- and vegetable-fish co-culture, which are unique in Asia, have also been shown to promote ecological intensification of agriculture (Wan et al., 2019a, 2019b, 2020). For example, the presence of fish decreased herbivore insect abundance by 24.1%, reduced weeds abundance, richness and biomass by 67.6, 62.0 and 58.9% respectively, increased invertebrate predator abundance by 19.5%, and reduced the need for pesticide by 23.4%. In one study, rice-fish co-culture practice increased economic profit by 10.3% over standard, mono-rice farming, and it enhanced both soil and rice quality (Wan et al., 2019a).
In conclusion, increasing species diversity contributes to the enhancement of ecological intensification in agriculture, as indicated by increases in beneficial organisms and plant performance (growth, reproduction and quality), decreases in pests and pesticides, and an increase in economic profits. Thus, I propose that increased species diversity is one of the keys to decreasing the negative environmental effects of agricultural production, and should be a focus of research and in practice.
Nian-Feng Wan (Eco-environmental Protection Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai, 201403, China; Institute of Biodiversity Science, Fudan University, Shanghai, 200438, China)
Acknowledgment: I thank Jacob Weiner for help with the English.
1. Gurr GM, Lu Z, Zheng X, Xu H, Zhu P, Chen G, Yao X, Cheng J, Zhu Z, Catindig JL, Villareal S, Van Chien H, Cuong leQ, Channoo C, Chengwattana N, Lan LP, Hai leH, Chaiwong J, Nicol HI, Perovic DJ, Wratten SD, Heong KL, 2016. Multi-country evidence that crop diversification promotes ecological intensification of agriculture. Nature Plants, 2: 16014.
2. Wan NF, Cai YM, Shen YJ, Ji XY, Xu XW, Zheng XR, Cheng W, Li J, Jiang YP, Chen X, Weiner J, Jiang JX, Nie M, Ju RT, Yuan T, Tang JJ, Tian WD, Zhang H, Li B, 2018. Increasing plant diversity with border crops reduces insecticide use and increases crop yield in urban agriculture. eLife, 7: e35103.
3. Wan NF, Li SX, Li T, Cavalieri A, Weiner J, Zheng XQ, Ji XY, Zhang JQ, Zhang HL, Zhang H, Bai NL, Chen YJ, Zhang HY, Tao XB, Zhang HL, Lv WG, Jiang JX, Li B, 2019a. Ecological intensification of rice production through rice-fish co-culture. Journal of Cleaner Production, 234: 1002-1012.
4. Wan NF, Chen J, Ji XY, Chacón-Labella J, Zhang H, Fan NN, Jiang JX, Li B, 2019b. Co-culture of multiple aquatic species enhances vegetable production in coastal Shanghai. Journal of Cleaner Production, 241: 118419.
5. Wan NF, Su H, Cavalieri A, Brack B, Wang JY, Weiner J, Fan NN, Ji XY, Jiang JX, 2020. Multispecies co-culture promotes ecological intensification of vegetable production. Journal of Cleaner Production, 257: 120851.