Results from the earlier studies favored narrow row spacings while more recent studies showed essentially no yield differences among row spacings ranging from 6-12 inches. Based on the more recent findings, it can be concluded that row spacing is not the most limiting factor to crop production in Western Canada. Although there may be some conflicting results, there is enough evidence to support using wider row spacings as a means of dealing more effectively with heavy residue conditions under zero tillage. A better understanding of why the different conclusions would allow for greater opportunities to maybe increase grain yields with the wider row spacings using a whole farm, production system approach. Another way to get a better appreciation of how crops respond to changes in row spacing and seeding rates is to examine how the plant compensates with changes in these two factors.
Cereal crops are a good model to use because yield components are easy to measure.
On the other hand crops like canola, flax, field pea are more difficult to quantify given their more indeterminant growth habits. I will restrict this part of the discussion to cereals. 3.1 Grain Yield and Yield Components in Cereals. If the values for these three components are known, final gain yield can be accurately predicted. As a rule, the main head and the first three primary tillers are the most productive.