Ants and termites have a significant positive impact on crop yields in dryland agriculture, according to a paper published in the journal Nature Communications by scientists at CSIRO and the University of Sydney.
"Ants and termites perform the same ecosystem service functions in dryland agriculture that earthworms perform in cooler and wetter areas, but the potential for ants and termites to provide these benefits has received little attention until now," said CSIRO's Dr Theo Evans.
"We already knew that the activities of ants and termites affect soil structure, aeration, water infiltration and nutrient cycling in natural ecosystems but we wondered whether they also perform these services in agricultural landscapes."
"Our studies on ants and termites in soil showed an average 36 per cent higher wheat crop yield under low tillage but otherwise conventional agricultural management," Dr Evans said.
This is the first study to show a crop yield increase due to soil fauna in the field.
"We believe there are two main reasons for the increase in yield. First, tunnels dug by ants and termites let more rain penetrate deeper into the soil where plants can access it, which also reduces runoff and evaporation. Second, the insects improve soil nitrogen, probably because termites have nitrogen fixing gut bacteria (functionally similar to those in the root nodules of legumes), which could help reduce fertilizer costs," Dr Evans said.
"We suspected that ants and termites may be a useful management tool for farmers, based on previous knowledge gained from studies in natural ecosystems, but we were very surprised by the large size of their influence in agricultural systems," he said.
"The benefits of ants and termites are likely to be greatest in hot and dry climates where water is a limiting resource for plant growth, due to their positive effect on water infiltration into the soil," he said.
Dr Evans said the next big challenges are to identify soils that can gain the most benefits, the most beneficial species and how to promote their return to farms where they have been lost due to decades of intensive tillage and pesticide use.
- Theodore A. Evans, Tracy Z. Dawes, Philip R. Ward, Nathan Lo. Ants and termites increase crop yield in a dry climate. Nature Communications, 2011; 2: 262 DOI: 10.1038/ncomms1257
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