CROPPING SYSTEMS FOR SPRING AND WINTER CEREALS UNDER SIMULATED PASTURE - YIELD AND YIELD DISTRIBUTION

Annual crops are used routinely for pasture in many parts of the world , but in Alberta they are used primarily to offset feed shortages. Exp eriments were conducted during 1987 and 1988 at Lacombe, Alberta under dryland conditions and at Brooks. Alberta under irrigation to determi ne the feasibility of using spring-planted combinations of spring and winter cereals to extend the grazing season. Treatments for simulated grazing were spring oat (Avena sativa L.), and barley (Hordeum vulgare L.) monocrops (SMC), winter wheat (Triticum aestivum L.) and winter t riticale (X Triticosecale Wittmack) monocrops (WMC), spring and winter cereal binary mixtures, seeded together in the spring (intercrop-IC) and the winter cereal seeded after one clipping of the spring cereal ( double crop-DC). Clippings were initiated at the jointing stage of the spring cereals and were repeated at intervals of 4 wk. The SMC produc ed the highest yields during the first two cuts (mid-June and mid-July ), but regrowth declined thereafter. The WMC generally had superior yi elds after mid-July. The IC yield was similar to the higher of the SMC or WMC at any cut with more uniform productivity over the growing sea son. The DC was inferior to the IC for late summer and fall production . Averaged over years the IC produced 92 and 87% as much DM in the fal l as the WMC at Lacombe and Brooks, respectively. Yield totalled over all cuts resulted in the sequence IC > WMC > DC > SMC. The IC is a fea sible season-long pasture system under irrigation in southern Alberta and under rain-fed conditions in central Alberta.