Monday, 2 May 2011

Ants and termites – doing for Australia what earthworms do in wetter climes?

I first heard about this study while listening to the weekly CSIROpod(cast) from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) based in Canberra, Australia.
The paper, published in Nature Communications, described an Australian study investigating the role of ants and termites on crop yields in dryland agriculture. According to the researcher, Dr Theo Evans, while ants and termites have traditionally been considered pests they may actually provide to dryland agriculture the same kind of benefits that earthworms provide in wetter areas. The study found that where these insects were present, wheat yields increased by as much as 36%, soil water infiltration was improved and soil nitrogen (N) levels were higher.

The precise mechanisms for increasing N were unknown, but termites, which in wheat fields will feed mainly on protein-deficient stubble, use symbiotic gut microbes to fix atmospheric N, in a similar way to legumes. This fixed N is used to make protein for the termite and excess is excreted through defecation, which helps to raise N levels in the soil. Concerns regarding damage to wooden buildings and other infrastructure caused by termites are unfounded as the majority of termite species found in Australia don't eat wood.

Ant and termite populations can be encouraged in the same way that farmers in wetter regions encourage earthworms, such as by reducing soil disturbance through the use of conservation agriculture, as well as simply ploughing shallow and less, using controlled traffic farming to reduce compaction and reducing use of agrochemicals.

The study, conducted in the northern edge of the West Australian wheat belt, also found that ants fulfil a secondary purpose of eating weed seeds. While ants also tend to prey on termites, the two insects are often found in the same habitat. Both types of invertebrate build nests in the soil and provide similar types of ecosystem services.