INTERACTIONS OF ZINC WITH BANDED AND BROADCAST PHOSPHORUS-FERTILIZER ON THE DRY-MATTER AND SEED YIELD OF OILSEED FLAX

Field experiments at four sites over 3 yr evaluated the effect of banded and broadcast application of fertilizer P, with and without application of Zn on dry matter yield at flowering, and seed yield of flax. Application of P fertilizer increased dry matter yield and seed yield on a number of soils even when crop growth and yield were restricted by extremely dry conditions. Banded P was more effective than broadcast or residual P in increasing flax yields. Increases in yield due to Zn application were infrequent and showed no definite relation to soil Zn or P. Increases in yields with Zn application generally occurred only where P had been broadcast that season or the year before, while decreases in yields with Zn occurred more frequently where P had been banded. The results showed that increases in flax yields in response to Zn application are most likely to occur where P fertilizer is broadcast at relatively high levels or on soils with a history of heavy P application.