Fertilizer N management and P placement effects on yield, seed protein content and N uptake of flax under varied conditions in Saskatchewan

In the Canadian prairies, producers prefer to seed and apply all fertilizer nutrients in one operation, but placement of fertilizers at high rates in the seed row can reduce crop emergence. Recently, specialized equipment has been developed to minimize or prevent damage to seedlings by maintaining a safe separation between seed and fertilizer. A 3-yr (2000 to 2002) field study was conducted to determine the effect of N formulation (urea and anhydrous ammonia), placement (broadcast, side-band and mid-row band), timing (fall and spring) and rate (0 to 90 or 120 kg N ha(-1)), and P placement (7-10 kg P ha(-1)) on plant density, seed and straw yield, seed protein content, and N uptake in seed and straw of flax (Linum ustatissimum L.) under no-till at four sites (Indian Head, Black Chernozem soil - Udic Boroll; Melfort, Dark Gray Luvisol soil - Mollic Cryoboralf, Swift Current, Brown Chernozem soil - Aridic Boroll; and Scott, Dark Brown Chernozem soil - Typic Boroll) in Saskatchewan. There was a significant increase at 10 of 12 site-years for seed yield, at 5 site-years for straw yield, at 12 site-years for seed protein content, at 11 site-years for seed N uptake, and at 8 site-years for straw N uptake with increasing N fertilizer rate, but the responses were generally small to moderate and varied with placement, form and timing of N application, and placement of P fertilizer in a few cases. Side-banded N fertilizer treatments reduced plant emergence at 3 site-years for urea and at 4 site-year for anhydrous ammonia, but the plant densities were considered adequate for optimum yield. Seed and straw yield, seed protein content, and N uptake in seed and straw were generally similar between side-banded and mid-row-banded N fertilizer, and also similar between urea and anhydrous ammonia in most cases. Occasionally, there was a trend of seed yield reduction with seed-placed P compared with side-banded P, side-banded urea was more effective than broadcast urea, and fall banded N less effective than spring side-banded N. In conclusion, there were few differences in the agronomic performance of urea vs. anhydrous ammonia and side-band vs. mid-row band. The findings did suggest that broadcast urea can be less effective than side-banded urea, fall banded N can be inferior to spring banded N, and seed-placed P can reduce seed yield compared with side-banded P.