Study links crop diversity and need for pesticides

Crop diversification has been shown to be an effective practice for improving diverse ecosystem services, including the regulation of insect pests, weeds and pathogens. However, the quantitative relationship between crop diversification at the cropping system scale and pesticide use has rarely been addressed, being mainly supported by landscape-scale evidence or some long-term experiments.

Crop diversification can reduce pesticide use in two main ways:

(a) effect of the type of crop: some crops have a lower inherent need for pesticides;

(b) effect of cultural diversity: The presence of multiple crops in a cropping system helps regulate pests more effectively.

These two effects combined result in a net impact at the cropping system scale, which can be difficult to differentiate through experimental design or modeling approaches.

To better understand these effects, the French national network Dephy database was used, which describes 1285 cropping systems and 67 commercial crops. Study by researchers from Bourgogne Franche-Comté University, Toulouse University and China Agricultural University (Beijing) aimed to disentangle and quantify the two complementary effects on pesticide use at the cropping system level.

The survey results show that:

• crop species explain 37,1% of the total variation in pesticide use across cropping systems;

• cultural diversity explains 1,3% of this variation;

• other factors explain the remaining 38,7%.

When excluding the effect of crop species, the addition of a crop to the cropping system was found to decrease total pesticide use by 0,09 treatment frequency index units on average.

The researchers highlighted the need for additional studies to better understand the effects of crop species characteristics, as well as consider other factors such as climatic conditions.

Article about the study can be read at doi.org/10.1016/j.eja.2024.127263