The effect of daytime temperature, planting density and intercropping on oats and peas

Oats and peas are grown throughout Canada and around the world as a nutritious feed for cattle. Commonly, farmers grow oats and peas together in the same field (i.e., intercropped) to produce forage that is higher yielding and more nutritious than individually-grown oats or peas. Given the importance of oats and peas to the cattle industry, investigating and understanding how climatic factors and growing methods affect yields is important. Previous studies have shown that greatest yields are achieved when daytime temperatures are between 15°C and 20°C, oats and peas are intercropped, and a high planting density is used. However, these three factors have not been investigated together in one experiment before. Therefore in this project, the interacting effect of daytime temperatures, planting densities and cropping methods were studied. Using a climate-controlled greenhouse, oats and peas were grown together and apart at three different planting densities and daytime temperatures. Contrary to previous studies, I found that temperatures above 20°C positively affected oat and pea yields. However, leaf count and plant height data indicate that these plants were simply maturing earlier. As expected, planting density positively affected yields in both species. Individual yield data shows that per-plant yields did not vary with density. This indicates that plant growth was not nutrient limited. Thus, increases in yield with planting density are almost wholly attributable to the increased number of plants per area. Finally, I found that intercropping oats and peas together resulted in yields intermediate to sole-cropped oats and peas. No difference in individual plant weights, leaf counts or heights were observed between plants that were sole or intercropped. Thus, it might be that intercropping oats with peas does not positively affect yields when plants are not nutrient limited, and that increased yields obtained when these two species are intercropped results primarily from an increase in planting density. To validate these observations, I recommend repeating this study with a larger number of replicates and harvesting all treatments at the same stage of maturity.