Cover crop effects on spring soil water content and the implications for cover crop management in south coastal British Columbia

Soil water content in the spring is an important factor in making decisions on cultural operations. A 2-year study was conducted to determine the effects of fall planted cover crops on spring soil water content dynamics and to relate the water content to cover crop management in terms of field trafficability. Each year, cover crops were planted at two planting dates in the fall, late August and late September on a loamy, mixed, mesic Humaquept on the Fraser River delta, south coastal British Columbia. Treatments were bare (control), wheat, rye and spring barley. Soil samples were collected at approximately biweekly intervals beginning in early spring to determine soil water content. Plant samples were also obtained late in the spring to determine C:N ratio. Treatments affected soil water content differently at each sampling date. No differences in soil water content at depths 2040 and 40-60 cm were observed. Critical soil water content value for trafficability was determined to be 0.32 kg kg(-1). Cover crops attained critical C:N ratio of 31.7:1 when the soil water was still above the critical value. The results suggest that terminating the cover crop growth in the spring could best be done by either mowing or spraying the cover crops as opposed to incorporation in order to minimize compaction since the critical C:N ratio for net mineralization is achieved when the soil is still too wet. (c) 2006 Elsevier B.V. All rights reserved.