Organic and conventional management of mixtures of wheat and spring cereals

Cereal mixtures may provide both organic and conventional producers with a more sustainable approach in reducing weed pressure, crop rotation flexibility, improved yield stability, buffering against pests and diseases, minimizing soil variability and increasing animal feed value. We examined the response of small grain mixtures containing wheat, oats, barley and triticale to varying degrees of natural competition and environmental stress at three locations in central Alberta, Canada. One modern and one heritage hard-red spring wheat cultivar, along with one cultivar each of oats, barley and triticale and eighteen two-way mixtures, were planted on organic and conventional land at seven location-years between 2003 and 2005. Average yields were 30% to 70% lower on organically managed sites. Monocrop barley yielded 43% and 16% higher than the site average at two organic locations. Our results suggest two main conclusions: (1) on conventionally managed land, wheat-barley mixtures exhibited potential for yield maintenance and weed suppression, and; (2) on organically managed land, competition with weeds had a large negative effect on yield (>30%). The 25:75 mixtures of wheat and oats, and all mixtures of Park (a heritage) wheat and Manny barley exhibited yield potential similar to or (up to 1.0 t ha−1) greater than monocrop yield. Manny barley mixtures exhibited weed suppressive capabilities.