Traditionally the mind set surrounding oats was that you could seed them late and still harvest a crop or if you needed extra forage you could cut it for green feed. In a tillage cropping system, the tillage created a big spike in the emergence pattern of wild oats and more often than not, the tame oats emerged after the wild oats. Late seeding took away some of the risk for the farmer but the trade off was that they gave up yield and test weight.
So what has changed about oat production? A much larger percentage of the oat crop is now sold off the farm and yield and test weights have become much more important. At Indian Head, yields in oats have been reduced by 60 bushels an acre by delaying seeding from May 15 to June 15. The reduction is not always this large but the trend has been observed at Melfort, Canora, Saskatoon, Indian Head, Brandon and Winnipeg (Table 1 and Figure 1). The reduction in test weight with delayed seeding is even more pronounced than the yield reduction (Figure 2). If you are in a rust area, the risk of a loss in yield and test weight is even higher.
Low disturbance direct seeding has two effects on wild oats. The first is that the reduction in tillage removes the spike in wild oat emergence. Instead, wild oat emergence occurs over the whole growing season. In fact, you can wait a long time in the spring until most of the wild oats have emerged. The ability to control wild oat emergence has been lost and therefore the risk reduction gained by delayed seeding is also lost. However, low disturbance seeding offers less stimulation for wild oats, which is a benefit. Concurrently, our mind set for fertilizer application has also changed. Research has proven that broadcast fertilizer can give wild oats a competitive advantage over the crop compared to when the fertilizer is banded.
Spreading out the emergence of the wild oats combined with the reduction in the competitiveness of the wild oats, opens the door to plant oats earlier and still have higher yield and test weight and while managing wild oats. If you primarily use oats as on farm feed and your cropping system still uses a moderate amount of tillage, delayed seeding may be a good crop production practice for your farm operation
In a direct seeding system wild oats still must be managed. The use of high seeding rates, over 300 plants per metre is important. Much more research is needed in Western Canada to provide the farmer with information on the importance of row width, cultivars, crop rotation, fertilizer placement and fertilizer timing on the management of wild oats in oats. We're working on it.
Figure 1. The effect of planting date on the yield of four oat cultivars at Melfort in 1999
Figure 2. The effect of seeding date and cultivars on test weigh at Indian Head in 1998