The effects of dryland cropping system intensity on soil function and associated changes in macrofauna communities

Crop production in water-limited environments may be enhanced through improved soil function by facilitating precipitation capture and erosion control. Soil macrofauna are known to support improved soil structure and water dynamics through ecosystem engineering activities, and their populations can be influenced by management. We examined the effect of bare summer fallow frequency on soil macrofauna communities and soil physical properties in a long-term (32-yr) dryland no-till agroecosystem experiment at two sites in eastern Colorado, USA. Treatments represented a gradient of fallow frequency and organic matter inputs, which included wheat (Triticum aestivum L.)-fallow, wheat-corn (Zea mays L.)-fallow, and continuously cropped with no planned summer fallow. The design also included a perennial grass treatment with minimal management consisting of six native grasses. We observed links between soil macrofauna and soil functional metrics, particularly related to soil aggregation and water infiltration. There was a trend toward higher macrofauna populations and soil function with increased cropping system intensity, and perennial grass outperformed the cropped treatments significantly for most soil health parameters. Multivariate analyses revealed that different treatments support relatively distinct macrofauna communities. Our results suggest that soil macrofauna populations may be important facilitators of soil structure and associated water dynamics in dryland no-till agroecosystems and respond positively to reduced fallow and higher organic inputs.