Near-Surface Soil Property Responses to Forage Production in a Semiarid Region.

Integration of perennial forages in annual cropping systems can expand ecosystem service benefits to agricultural landscapes. Such benefits are frequently derived from changes to soil properties. Unfortunately, there is limited guidance for agricultural producers regarding the length of time needed to accrue soil condition improvements under perennial forages, particularly for semiarid regions. The objective of this study was to quantify soil responses to perennial grasses, legumes, and grass–legume mixtures over a 5-yr year period in a semiarid region. Select soil physical and chemical properties were measured within five perennial forage treatments and under annual cropping over a 5-yr period on a Parshall fine sandy loam near Mandan, ND. Treatment effects on soil properties were limited to the surface 10 cm. Differences in soil properties between spring wheat (Triticum aestivum L.) and perennial forages were most frequent following the fourth stand year. Compared with spring wheat, perennial forages mitigated soil acidification (by 0.26–0.65 pH units), reduced soil bulk density (by 0.04–0.08 Mg m–3), and increased particulate organic matter (POM) (by 0.41 g C kg–1) and water-stable aggregates (by 3.8%). Among perennial forages, intermediate wheatgrass (Thinopyrum intermedium L.) and intermediate wheatgrass–field pea (Pisum sativum L) mixture followed by alfalfa (Medicago spp.) reduced soil bulk density (by 0.06–0.11 Mg m–3) and increased POM (by 0.24–0.92 g C kg–1) compared with alfalfa following 4- and 5-yr perennial forage stands. While these outcomes suggest perennial forages can improve the near-surface soil condition, accrual of improvements may be slow and subtle in semiarid regions. [ABSTRACT FROM AUTHOR]