What do ants and soils do for each other?

Have you ever wondered how important ants are for agriculture and soils? They do not get much credit for their contribution towards our planet Earth. Moreover, many people dislike them. Don’t we? We certainly don’t appreciate them in our homes – or on our picnic tables!

Imagine a situation where you are in a corn field taking plant height data. In no time you step on the ants’ colony (nest) and suddenly a battalion of ants marches all over your body. Think! Think!! Yes, you read it right- a battalion of ants. Scary, but ants are valuable to our ecosystem.

worker ants outside the main entrance to their home
Worker ants outside the main entrance to their “home,” which includes a series of tunnels and chambers. Credit: SV Fisk 

Interesting facts about ants

Like humans and bees, ants live a social life. They have their own complex societies. These societies have division of labor. Queen ants lay eggs for future generations. These eggs hatch into larva. Numerous non-reproductive adult ants in these societies serve as laborers. The army of laborers collect decayed and dead matter and plant parts from outside the nest and bring inside to feed larvae.

Laborers are also responsible for carrying the leftovers outside and maintaining the hygiene of the nest. Wondering how they do so? They have a leader who directs the army and entire members march in a line.

These battalions of ants make their nest in soil. Soil provides them shelter. These nests are known as mounds and have many chambers in it. These chambers are connected via tunnels. Increased connectivity between chambers means more social interaction among ants. Higher number of tunnels also indicates more food present in the nest for colonies.

a detailed view of an ants nest
Ants nest formed with the help of soil at Texas A&M University Farm, College Station, Texas. Credit: Rahul Raman  

How do ants help soil?

Ants represent almost half of the insect population worldwide. Nests formed by ants cause loosening of soil that increases water infiltration and soil aeration (from all those tunnels). This influences soil hydrology and crop physiology. Increased water infiltration increases the soil moisture content, which increases the plant water and nutrient uptake that contributes to photosynthesis and transpiration. Higher rates of photosynthesis results in increased plant vegetative growth and/or yield. Increased soil aeration promotes microbial activities within the soil.

ant hill on soil
Ant hills can actually serve as a mulch, according to research done in China. Photo courtesy T. Li.

Plant parts and other dead and decayed materials carried by ants for their food also contributes to the topsoil, thus enriching soil organic carbon and other organic matter content. Ants also enrich the nitrogen content of soil. Bacteria present in ants’ gut help them to fix atmospheric nitrogen. However, in the process of nest construction these gut bacteria are transferred to soil, thus making topsoil and subsoil rich in nitrogen. This process ultimately helps plants in their growth and development. Increases in microbial activities in subsoil due to aeration results in increased nutrient content that can be used by plants for their growth and development. Ants also maintain the neutral pH of soil by altering the soil chemically.

ants foraging on sunflower plant
Ants foraging on a sunflower plant. Many ants look for food on plants when it’s hard to find on the soil surface. Credit: Naim Edwards

For decades, soil health has been affected due to soil erosion caused by different agricultural practices and land use. Reduction in soil residue cover, deforestation, etc. are major factors disturbing soil health. In such cases, presence of ants’ colonies and nests can be used as bioindicator in rural areas to confirm good health of soil. The presence of ants is a good thing! Overall, soil and ants share a mutual relationship.

Answered by Rahul Raman, Texas A&M

Read more about ants and soils in “Making Mulch Ado About Ant Hills.”

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