Cyclic Yield Stability of Ley Farming System in Northern Quebec

Predicted climate change is a threat to dairy farming operations in northern Quebec. Soil conservation measures and the time-frame of crop management may contribute to reducing yield variability and also support dairy herd populations. Our objective was to compare annual and cyclic barley (Hordeum vulgare L.) and forage yield stability for 3-yr ley farming system (barley-mixed, forage-mixed, forage) over 24 yr of experimentation under contrasting soil conservation practices. Treatments were chisel or moldboard plowing, and mineral fertilization (MIN) or liquid dairy manure (LDM) applied cyclically (across eight 3-yr cycles) at 85 to 209 kg LDM-N ha(-1) and 90 to 146 kg MIN-N ha(-1) to forage and 87 to 127 kg LDM-N ha(-1) and 70 kg MIN-N ha(-1) to barley. Yield stability assessment was initialized in 1993, 1994, and 1995 and ended in 2014, 2015, and 2016, respectively. While the cyclic assessment showed no significant effect of tillage practice, LDM outperformed MIN, confirming the benefits of manure-based ley farming systems for dairy farming. Coefficients of variation ranged from 7.8% to 14.4% for barley grain yield, 14.4% to 18.7% for barley straw yield, and 11.8% to 15.3% for forage yield. Coefficients of variation were reduced by factors of 1.86 +/- 0.57, 1.87 +/- 0.24, and 2.00 +/- 0.25 for grain, straw, and forage, respectively, using cyclic assessments. To face the more frequent extreme meteorological events predicted by regional climatic models, feed supply could be stabilized locally and regionally at cyclic rather than yearly timescales to support dairy farming.