Soil Quality Change Under a Long-Term Integrated Crop-Livestock Production System in a Cold, Semiarid Region.

Long-term evaluations are needed in cold, semiarid regions to understand trends in soil quality under integrated crop-livestock production systems.  To address this need, a study was initiated in 1999 near Mandan, ND to investigate effects of multiple-crop swath grazing systems on crop production, cattle performance, and soil quality.  Two swathed grazing systems [annual cropping under no-till management (AC) and western wheatgrass (WW)] were evaluated for their influences on near-surface soil properties before and after grazing within zones differing in frequency of cattle traffic and in ungrazed areas.  Soil bulk density, soil pH, extractable N and P, potentially mineralizable N (PMN), and soil organic carbon (SOC) were measured three, six, and nine years after treatment establishment.  Values for soil properties were incorporated into a soil quality index using the Soil Management Assessment Framework (SMAF) to assess overall treatment effects on soil condition.  Results from the study revealed few differences in soil properties between treatments.  Values for soil bulk density in the fall were not different from values observed in the spring, nor did the frequency of hoof action from cattle result in higher soil bulk density.  Comparison of AC with WW grazing systems exhibited no difference in SMAF soil quality index scores for soil properties at the surface 7.5 cm depth after nine years.  Limited nutrient removal and natural amelioration processes likely contributed to resilience of surface soil properties to system perturbations.  Results from the study suggest agricultural producers can convert perennial pastures to a winter-grazed annual crop management system without adversely affecting soil quality.