The interactions of row spacing and seeding rate with seed placed phosphorus

Evaluate the effects of row spacing, seeding rate, and N and P fertilizer placement in spring and winter wheat, barley, durum and flax under no-till cropping.


30 Aug 2001


    The development of zero-till or direct seeding production systems implies working with standing stubble and surface residues. Residue management and the ability of seeding implements to plant in those conditions are the key to success with these new crop production systems. Recently, research has shown that higher yields can be obtained with narrow row spacings. However this conflicts with the efforts of getting producers to adopt conservation tillage because it will make zero-till more difficult not to mention the increased soil disturbance, cost of seeding equipment and draft requirements. Studies were initiated in 1989 at Indian Head to re-evaluate the effects of row spacing, seeding rate and nitrogen fertilizer in spring and winter wheat, barley, durum and flax under zero-till conditions. The purpose was to determine what yield decreases would be observed with 30 cm row spacings, if any, and whether the lower yields could be offset by more favorable economics with wide row spacing. Our results have shown that in fact, no yield losses were observed by going to 30 cm row spacings. In the case of durum, we have consistently observed better yields on 30 cm row spacing than 10 or 20 cm. These results conflict with previous results and we are presently trying to determine the reasons for the discrepancy between our results and those of other researchers in Saskatchewan. I should mention that Dr. Byron Irvin at S.I.D.C. in Outlook, SK has repeated the row spacing studies under irrigation and is observing similar results to me. I examined the methodology used in the other studies and found some confounding effects, mainly with the management of phosphorus. In some studies the amount of phosphorus was kept constant per row thereby biasing against wide row spacings. In other studies, the balance of the phosphorus was broadcast on the surface in order to make the rates per area similar between row spacing. In our studies, we have kept phosphorus constant per area and consequently the amount of phosphorus per row increases as row spacing increases. We postulate that the row spacing effects observed in the past are a function of P management and that in fact proper management of P can alleviate the observed yield decreases at wide row spacing from previous studies.