Organic transition significantly increases important soil insects in tropical sugarcane

A recent study published in the journal Applied Soil Ecology found that after only 1-2 years after transitioning from conventional to organic practices, important soil invertebrate communities can be restored. Tropical systems are extremely reliant on saprophagous insects, those that break down decaying plants and animals, for their role in sustaining soil fertility. This is especially important for tropical cropping systems like sugarcane. However, those same cropping systems also often rely on pesticides and herbicides causing concern for beneficial biodiversity including soil insects that are critical for nutrient cycling and soil health. For instance, in sugarcane operations, herbicides are often used to desiccate (dry out) the crop for harvest.  While sugarcane can be grown in the same spot the following season, the repeated use of these herbicides, most commonly glyphosate, may impact other important aspects of the natural agroecosystem.

To get a sense of the impacts of using pesticides in sugarcane, this study measured soil insect abundance and diversity in sugarcane fields under conventional management and that recently transitioned to organic. Researchers found that one important group of soil insects, saprophagous insects, increased by 234% in the organically managed sugarcane. Different insect groups responded differently and while overall soil insect diversity did not differ between conventional and recently transitioned organic fields, there was a clear impact of pesticides on a critical insect group. The authors suggest that the intensive chemical use is responsible for the impact on soil insects, but also suggest that these results show that even a short period of transitioning away from chemical use can help restore the important soil biodiversity needed for healthy soils in farming systems.

Banner Photo Credit: Ashwini Chaudhary;