Ant burrow effects on water flow and soil hydraulic properties of Sparta sand

Abstract

Macropores generally have a significant influence on soil hydrologic processes. Ants create large burrows that may function as macropores, thus creating a potential for rapid movement of water and water-soluble chemicals in soil. This study was conducted to characterize the impact of ant burrows on hydraulic properties of a Sparta sand (uncoated, mesic Typic Quartzipsamments), and to determine the potential for preferential flow of water in these macropores. We measured steady-state water flux in areas with and without ant burrows, using a tension infiltrometer, in no-till (NT) and moldboard-plow (MP) maize ( Zea mays L.) plots. The results from these measurements were used to estimate hydraulic conductivity of saturated soil, K s, soil macroporosity, Φ m( r), and macroscopic mean pore radius, r c. Because, during a rain or irrigation event, only those ant burrows that open to the soil surface would contribute to water flow, we also monitored the impact of sprinkler irrigation on the number of burrow openings. Macropores created by ant burrowing activities did not contribute significantly to water flow in this sandy soil, and they had little effect on K s, Φ m( r), and r c in either NT or MP plots. One of the main reasons for the lack of burrow effect on water flow was that the burrow openings tended to close during an irrigation or rain event. We found that 80% of the total burrows in a given area closed after the application of 5 mm of irrigation; however, 80% of these were reopened within 2 h.